Mechatronics arose as a complex science from the fusion of separate parts of mechanics and microelectronics. It can be defined as a science dealing with the analysis and synthesis of complex systems that use mechanical and electronic control devices to the same extent.
All mechatronic systems of cars are divided into three main groups according to their functional purpose:
- - engine control systems;
- - transmission control systems and undercarriage;
- - cabin equipment control systems.
The engine management system is subdivided into gasoline and diesel engine management systems. By design, they are monofunctional and complex.
In monofunctional systems, the ECU only sends signals to the injection system. The injection can be carried out continuously and in pulses. With a constant supply of fuel, its amount changes due to a change in pressure in the fuel line, and with a pulse, due to the duration of the pulse and its frequency. Today, one of the most promising areas of application of mechatronic systems is automobiles. If we consider the automotive industry, the introduction of such systems will allow us to achieve sufficient production flexibility, better catch fashion trends, quickly introduce advanced developments of scientists, designers, and thereby obtain a new quality for car buyers. The car itself, especially modern car, is the object of close scrutiny from a design point of view. The modern use of a car requires from it increased requirements for driving safety, due to the ever increasing motorization of countries and tightening standards for environmental friendliness. This is especially true for megacities. The answer to today's challenges of urbanism is the design of mobile tracking systems that control and adjust the performance of components and assemblies, achieving optimal performance in terms of environmental friendliness, safety, and operational comfort of the vehicle. The urgent need to equip car engines with more complex and expensive fuel systems is largely due to the introduction of more and more stringent requirements for the content of harmful substances in exhaust gases, which, unfortunately, is just beginning to be worked out.
In complex systems, one electronic unit controls several subsystems: fuel injection, ignition, valve timing, self-diagnostics, etc. The electronic diesel engine control system controls the amount of injected fuel, the moment of injection start, the current of the torch plug, etc. In an electronic transmission control system, the subject of regulation is mainly automatic transmission... Based on signals from the opening angle sensors throttle and vehicle speed, the ECU selects the optimal transmission ratio, which improves fuel efficiency and controllability. Chassis control includes the control of the processes of movement, trajectory changes and braking of the vehicle. They act on the suspension, steering and braking system and maintain the set speed. The interior equipment management is designed to increase the comfort and consumer value of the vehicle. For this purpose, an air conditioner, an electronic instrument panel, a multifunctional information system, a compass, headlights, an intermittent wiper, an indicator of burned out lamps, a device for detecting obstacles while driving are used. reverse, anti-theft devices, communication equipment, central door locks, glass lifters, variable position seats, security mode, etc.
T ermin " mechatronics»Introduced by Tetsuro Moria (Tetsuro Mori) as an engineer of the Japanese company Yaskawa Electric (Yaskawa Electric) in 1969. Term consists of two parts - "fur", from the word mechanic, and "tronic", from the word electronics. In Russia, before the emergence of the term "mechatronics", devices called "mechatrons" were used.
Mechatronics is a progressive direction in the development of science and technology, focused on the creation and operation of automatic and automated machines and systems with computer (microprocessor) control of their movement. The main task of mechatronics is the development and creation of high-precision, highly reliable and multifunctional control systems for complex dynamic objects. The simplest examples of mechatronics are vehicle brakes with ABS (anti-lock braking systems) and industrial CNC machines.
The largest developer and manufacturer of mechatronic devices in the world bearing industry is the companySNR... The company is known as a pioneer in the field of "sensor" bearings, c the technology behind the know-how c using multi-pole magnetic rings and measuring components integrated into mechanical parts. ExactlySNRfor the first time proposed the use of wheel bearings with an integrated rotational speed sensor based on a unique magnetic technology -ASB ® (Active Sensor Bearing), which are now the standard recognized and used by almost all major car manufacturers in Europe and Japan. More than 82 million of such devices have already been produced, and by 2010 almost 50% of all wheel bearings in the world produced by various manufacturers will use the technologyASB ®... Such massive useASB ®once again proves the reliability of these solutions, providing high accuracy of measurement and transmission of digital information in the most aggressive environmental conditions (vibration, dirt, large temperature differences, etc.).
Illustration : SNR
Bearing structure ASB ®
The main advantages of technologyASB ®used in the automotive industry are:
it is a compact and economical solution, it can be used on vehicles of the lower price range, and not only on expensive cars unlike many other competitive technologies,
it is a progressive technology in the study of automotive comfort and safety,
it is the main element in the concept of “total chassis control”,
it is an open standard that minimizes the cost of licensing production to manufacturers of bearings and electronic components.
Technology ASB ®in 1997 at the exhibition EquipAuto in Paris received the first Grand Prix in the nomination "New technologies for original (conveyor) production".
In 2005 at EquipAuto SNRsuggested further development for reviewASB ®- a special system with a steering angle sensorASB ® Steering System, designed to measure the angle of rotation of the steering wheel, which will optimize the operation of the electronic systems of the car and increase the level of safety and comfort. The development of this system began in 2003, through the effortsCONTINENTAL TEVES and SNR Roulements... In 2004, the first prototypes were ready. Field testASB ® Steering Systemwere held in March 2005 in Sweden in cars Mercedes C -class and showed excellent results. To serial productionASB ® Steering Systemdue in 2008.
Illustration : SNR
ASB ® Steering System
The main advantagesASB ® Steering System will become:
simpler construction,
ensuring a low noise level,
lower cost,
size optimization…
With more than 15 years of experience in the development and manufacture of mechatronic devices, the company offers customers not only from the automotive industry, but also from industry and aerospace - "Mechatronic" bearingsSensor Line... These bearings have inherited unmatched reliabilityASB ®, full integration and compliance with international standards ISO.
Located in the heart of the movement, the sensorSensor Linetransmits information about angular displacement and rotational speed for more than 32 periods per revolution. Thus, the functions of the bearing and the measuring device are combined, which positively affects the compactness of the bearing and the equipment as a whole, while providing a competitive price in relation to standard solutions (based on optical sensors).
Photo : SNR
includes:
Patented multi-track and multi-pole magnetic ring that generates a defined magnetic field;
Special electronic component MPS 32 XF converts information about changes in the magnetic field into a digital signal.
Photo : Torrington
Component MPS 32 XF
Sensor Line Encodercan achieve a resolution of 4096 pulses per revolution with a reading radius of only 15 mm, providing a positioning accuracy of more than 0.1 °! Thus,Sensor Line Encoderin many cases can replace a standard optical encoder, while givingadditional functions.
Device Sensor Line Encodercan provide the following data with high accuracy and reliability:
angular position,
Speed,
direction of rotation,
Number of revolutions,
Temperature.
Unique properties of the new deviceSNRwere recognized in the world of electronics even at the stage of prototypes. Special sensor MPS 32 XF won the main prize Gold Award at Sensor Expo 2001 in Chicago (USA).
CurrentlySensor Line Encoderfinds its application:
in mechanical transmissions;
in conveyors;
in robotics;
v Vehicle Oh;
in forklifts;
in control, measurement and positioning systems.
Photo : SNR
One of the further projects to be completed in 2010-11 isASB ® 3- bearing with an integrated torque sensor based on the use of tunnel magnetoresistance. The use of tunnel magnetoresistance technology makes it possible to provide:
high sensitivity of the sensor,
low energy consumption,
the best signal in relation to the noise level,
wider temperature range.
ASB ® 4, scheduled for release in 2012-15, will conclude the era of information technology for bearing construction. For the first time, a self-diagnosis system will be integrated, which will allow, for example, the bearing's condition by the lubrication temperature of the bearing or its vibration.
Automobile transport plays an important role in the society, the transport system of the country, the economy. The vehicle is widely used for delivering goods to railways, river and sea berths, servicing industrial trade enterprises, agricultural workers, provides transportation of passengers. For a share road transport accounts for about half of passenger and cargo traffic (Fig.12.1)
Figure 12.1- Distribution of transportation
Literally a little over a hundred years have passed since the appearance of the first car, and there is practically no sphere of activity in which it would not be used. Therefore, the automotive industry in the economies of developed countries is now the leading branch of mechanical engineering. There are reasons for this:
Firstly, every day people need more and more more cars for solving various economic problems;
Secondly, this industry is knowledge-intensive and high-tech. She "pulls" many other industries, the enterprises of which carry out her numerous orders. The innovations introduced in the automotive industry inevitably force these industries to improve their production. Due to the fact that there are a lot of such industries, as a result, there is an increase in the entire industry, and, consequently, the economy as a whole;
Thirdly, the automotive industry in all developed countries is one of the most profitable sectors of the national economy, since it contributes to an increase in trade turnover and brings considerable income to the state treasury through sales on the domestic and world markets;
Fourth, the automotive industry is a strategically important industry. The development of this industry makes the country economically strong and therefore more independent. The widespread use of the best examples of automotive technology in the army undoubtedly increases the country's defense power.
Now in the automotive industry, there are a number of trends that indicate its importance and significance, as well as related industries in the economies of industrialized countries. There is a completely new approach to technical development car, organization and technology of its production. Scientific and technical trends are to reduce fuel consumption and emissions, develop an ultralight vehicle, improve safety, quality, reliability and durability, as well as develop intelligent road and road systems.
The development of mechatronics in cars (Fig. 12.2) and on production machines has its own characteristics. In automobiles, the expansion of automation, and therefore mechatronics, began primarily in the field of comfort devices. The first of the mechatronic units, as is historically the custom, there was an engine with a fuel supply system and automatic control of it. The second is the Power Attachment Control (EHR) system, the world leader in the production of which is Bosch. The third is the transmission. Here the process began with the appearance mechanical transmissions with switching of steps under load. They were equipped with hydraulic, then electro-hydraulic switching devices, and then electronic automatic switching control. Western firms (German ZF and others) began to supply car factories and produce for sale transmissions in such a complete set
The power and benefit of the mechatronic design of the units is especially clearly visible on the example of transmissions, which, in the presence and absence of automatic control with the same other components of the complex, show a striking contrast in the characteristics of both themselves and the vehicles equipped with them. In mechatronic form, they provide an order of magnitude more favorable characteristics in almost all indicators of machine operation: technical, economic and ergonomic.
Comparing mechatronic complexes with their non-mechatronic prototypes in terms of technical perfection, it is easy to see that the former are significantly superior to the latter, not only in general indicators, but also in the level and quality of design. This is not surprising: the synergistic effect is manifested not only in the final product, but also in the design process due to the new design approach.
Figure 12.2- Classification mechatronic systems car
When controlling the operation of a car engine, various systems are used:
- AVCS (Active Valve Control System)- The variable valve timing system on Subaru vehicles changes the valve lift depending on the instantaneous engine load. Common rail(Nissan) - an injection system that supplies fuel to the cylinders through a common rail under high pressure... It has a number of advantages that make driving more enjoyable for the driver: Common Rail diesels are characterized by both excellent throttle response and low consumption fuel, eliminating the need to often stop at gas stations.
- GDI- Gasoline Direct Injection, which can be translated as "engine with direct fuel injection", that is, fuel on such an engine is injected not into the intake manifold, but directly into the engine cylinders. M-Fire- combustion control system - the smoke content of the exhaust gases and the content of nitrogen oxides in them are significantly reduced, while the power is increased and the noise level is reduced.
- MIVEC(Mitsubishi) - optimally controls the moment of opening of the intake valves in accordance with the operating conditions of the engine, which improves the stability of the engine at idle speed, power and torque characteristics for the entire operating range.
- VTEC(Honda) - Variable valve timing system. They are used to improve the torque characteristics over a wide rpm range, as well as to improve the economy and environmental performance of the engine. Also applies to Mazda vehicles.
- DPS- Dual Pump System - two oil pumps connected in series (i.e. one after the other). At the same speed of rotation of both oil pumps, a "uniform" oil circulation takes place, i. E. there are no areas with high and low pressure (Fig. 12.3).
Figure 12.3- Dual Pump Sysytem
- Common rail(eng. common highway) - modern technology of fuel supply systems in diesel engines with direct injection. In system common rail the pump pumps fuel under high pressure (250 - 1800 bar, depending on the engine operating mode) into the total fuel line... Electronically controlled injectors with solenoid or piezoelectric valves inject fuel into the cylinders. Depending on the design, the injectors produce from 2 to 5 injections per cycle. Accurate calculation of the injection angle and the amount of fuel injected allows diesel engines to meet the increased environmental and economic requirements. Besides diesel engines with the common rail system in terms of power and dynamic performance have come close to, and in some cases have surpassed gasoline engines.
Allocate Various types mechatronic transmission device:
- CVT- automatic transmission with a variator. It is a mechanism with a range of change gear ratio more than a 5-speed manual transmission.
- DAC- Downhill Assist Control - the system controls the behavior of the car on steep slopes. The wheels are equipped with sensors that measure the speed of rotation of the wheels and constantly compare it with the speed of the car. Analyzing the data obtained, the electronics brakes the front wheels in time to a speed of about 5 km / h.
- DDS- Downhill Drive Support - a motion control system in Nissan vehicles on steep slopes. DDS automatically maintains a speed of 7 km / h when descending, preventing the wheels from locking.
- Drive Select 4x4- All-wheel drive can be switched on and off on the move at speeds up to 100 km / h.
- TSA(Trailer Stability Assist) - vehicle stabilization system while driving with a trailer. When the vehicle loses its stability, it usually begins to chatter on the road. In this case, the TSA brakes the wheels “diagonally” (front left - rear right or front right - rear left) in antiphase, while simultaneously reducing the vehicle speed by reducing the fuel supply to the engine. Used on Honda vehicles.
- Easy Select 4WD- system all-wheel drive widely used in Mitsubishi cars, allows you to change 2WD to 4WD, and vice versa, while the car is moving.
- Grade Logic Control- the system of "smart" gear selection, provides uniform traction, which is especially important when going uphill.
- Hypertronic CVT-M6(Nissan) - Delivers smooth, stepless acceleration without the jerkiness of traditional automatic transmissions. They are also more economical than traditional automatic transmissions. The CVT-M6 is designed for drivers who want to combine the advantages of automatic and manual transmissions with water. By moving the gear lever to the slot farthest from the driver, you get the opportunity to shift six gears with fixed gear ratios.
- INVECS-II- adaptive automatic machine (Mitsubishi) - automatic transmission with sport mode and the possibility of mechanical control.
- EBA- electronic pressure control system hydraulic system brakes, which, in the event of emergency braking and insufficient effort on the brake pedal, independently increases the pressure in the brake line, making it many times faster than a person. And the EBD system evenly distributes braking forces and works in conjunction with ABS - anti-lock braking system.
- ESP +- anti-skid stabilization system ESP - the most complex system using the capabilities of anti-lock, traction control with traction control and electronic throttle control systems. The control unit receives information from the sensors of the vehicle's angular acceleration, steering wheel angle, information about the vehicle's speed and the rotation of each of the wheels. The system analyzes this data and calculates the trajectory of movement, and if in turns or maneuvers the real speed does not coincide with the calculated one and the car "takes out" outside or inside the turn, corrects the trajectory of movement, braking the wheels and reducing engine thrust.
- HAC- Hill-start Assist Control - the system controls the behavior of the machine on steep inclines. HAC not only prevents wheel spin when starting up a slippery slope, but it can also prevent rolling back if the vehicle speed is too slow and it slides down under the weight of the body.
- Нill Holder- with the help of this device, the car is held on the brakes even after the brake pedal is released, the Нill Holder is disengaged only after the clutch pedal is released. Designed to start moving uphill.
- AIRMATIC Dual Control- active air suspension with electronic control and adaptive damping system ADS II works fully in automatic mode (Fig. 12.4). Compared to traditional steel suspension, it significantly improves ride comfort and safety. AIRMATIC DC works with airbags, which electronics depending on traffic situation makes it harder or softer. If the sensors, for example, have detected a sporty driving style, the air suspension, which is comfortable in normal mode, automatically becomes stiffer. The suspension and damping behavior can also be manually adjusted to Sport or Comfort mode using a switch.
The electronics work with four different damping modes (ADS II), which adapt automatically at each wheel to the road conditions. Thus, the car rolls smoothly even on bad roads without compromising stability.
Figure 12.4- AIRMATIC Dual Control
The system is also equipped with a function for adjusting the vehicle level. It provides almost constant ground clearance, which gives the car stability. When driving at high speed, the vehicle can automatically lower itself to reduce body tilts. Above 140 km / h, the vehicle is automatically lowered by 15 mm, and below 70 km / h, the normal level is restored again. In addition, for poor road conditions, it is possible to manually raise the vehicle by 25 mm. Continuously driving at a speed of about 80 km / h or exceeding the speed of 120 km / h will automatically return to the normal level.
Also in cars are used various braking systems used for a significant reduction in the braking distance, competent interpretation of the driver's behavior during braking, activation of the maximum braking force in the event of emergency braking recognition.
- Brake Assist (BAS) installed as standard on all passenger cars Mercedes-Benz interprets the behavior of the driver during braking and, in the event of emergency braking, generates maximum braking force if the driver himself does not press the brake pedal sufficiently. The development of the brake assist is based on the data received by the Mercedes-Benz Accident Research Department: in a critical situation, drivers press the brake pedal quickly, but not hard enough. In this case, the brake assistant can effectively support the driver.
For a better understanding, we will do short review modern braking systems technology: the brake booster, which increases the pressure generated by the driver's foot, consists of two chambers, which are separated by a movable membrane. If no braking is performed, then there is a vacuum in both chambers. By pressing the brake pedal in brake booster a mechanical control valve opens, which bypasses air into the rear chamber and changes the pressure ratio in the two chambers. The maximum effort is created when atmospheric pressure reigns in the second chamber. In the brake assist (BAS), a so-called diaphragm movement sensor detects whether the braking is extreme. It detects the movement of the diaphragm between the chambers and transmits the value to the BAS control unit. Constantly comparing the values, the microcomputer recognizes the moment when the speed of pressing the brake pedal (equal to the speed of movement of the diaphragm in the brake booster) exceeds the standard value - this is emergency braking. In this case, the system activates a magnetic valve, through which the rear chamber is instantly filled with air and the maximum braking force is generated. Despite such automatic full braking, the wheels are not blocked, because the well-known anti-lock braking ABS system doses the braking force, keeping it optimally on the verge of blocking, thus maintaining the vehicle's controllability. If the driver takes his foot off the brake pedal, a special actuation sensor closes the solenoid valve and the automatic brake assist is deactivated.
Figure 12.6- Brake assistant (BAS) Mercedes
- Anti-lock braking system (ABS)(German antiblockiersystem English Anti-lock Brake System (ABS)) - a system that prevents the vehicle wheels from locking when braking. The main purpose of the system is to reduce the braking distance and ensure vehicle controllability during hard braking, and to exclude the possibility of uncontrolled slipping.
The ABS consists of the following main components:
Speed or acceleration (deceleration) sensors installed on the vehicle wheel hubs.
Control valves, which are elements of the pressure modulator, installed in the line of the main brake system.
A control unit that receives signals from sensors and controls the operation of the valves.
After the start of braking, the ABS begins a constant and fairly accurate determination of the speed of rotation of each wheel. In the event that a wheel starts to rotate much slower than the others (which means that the wheel is close to blocking), a valve in the brake line limits the braking force on that wheel. As soon as the wheel starts to rotate faster than the others, the braking force is restored.
This process is repeated several times (or several tens of times) per second, and usually leads to a noticeable pulsation of the brake pedal. Braking force can be limited both in the entire braking system at the same time (single-channel ABS), and in the braking system of the board (two-channel ABS) or even an individual wheel (multi-channel ABS). Single-channel systems provide a fairly effective deceleration, but only if the traction conditions of all wheels are more or less the same. Multi-channel systems are more expensive and more complicated than single-channel systems, but they are more effective when braking on non-uniform surfaces, if, for example, when braking, one or more wheels hit the ice, a wet section of the road, or the side of the road.
Control and navigation systems are widely used in modern cars. .
- System DISTRONIC- carries out electronic regulation of the distance to the vehicle in front using the radar, simple control using the TEMPOMAT lever, provides additional comfort on the autobahns and similar roads, maintains the driver's working condition.
The DISTRONIC distance adjuster maintains the required distance to the vehicle in front. If the distance decreases, the braking system is activated. If there is no vehicle ahead, DISTRONIC maintains the speed set by the driver. DISTRONIC provides additional comfort for driving on the Autobahn and similar roads. The microcomputer processes the signals of the radar, which is installed behind the radiator grill, at a speed of 30 to 180 km / h. The radar pulses are reflected from the vehicle in front, processed and, based on this information, the distance to the front vehicle and its speed are calculated. If Mercedes-Benz car With DISTRONIC approaching the front vehicle too much, DISTRONIC automatically reduces throttle and applies the brake to maintain the set distance. If it is necessary to brake strongly, the driver is informed about this by means of an acoustic signal and a warning light - this means that the driver must press the brake pedal himself. If the distance increases, the DISTRONIC again maintains the required distance and accelerates the vehicle to the set speed. DISTRONIC is a further development of the standard TEMPOMAT function with variable speed limit SPEEDTRONIC
Figure 12.7- Control and navigation system
Mercedes-Benz introduced the first mechatronic air suspension AIR-matic with ADS damper regulation system in standard configuration S-class sedans.
In the AIR-matic system, the pillar of the S-class sedan contains a pneumatic elastic element: the role of springs we are used to is compressed air, enclosed under a rubber-cord shell. Also in the rack there is a shock absorber with an unusual "extension" on the side. Naturally, a full-fledged pneumatic system is provided in the car (compressor, receiver, lines, valve devices). And also - a network of sensors and, of course, a processor. How the system works. At the command of the processor, the valves open the access of air from the pneumatic system to the elastic elements (or bleed air from there). Thus, the level of the floor of the body changes: the system includes its dependence on the speed of the vehicle. The driver can also "show will" - to raise the car, say, to move over significant irregularities.
ADS performs more "delicate" work - controls shock absorbers. During the stroke of the shock absorber rod, part of the fluid flows not only through the valves in the piston, but also through the very "extension", inside which the actuator is a valve system that provides four possible modes of shock absorber operation. Based on the information received from the sensors and in accordance with the algorithm chosen by the driver ("sport" or "comfortable"), the processor selects for each shock absorber the mode most appropriate to the "current moment" and sends commands to the actuators.
Modern cars are equipped with climate control system. This system designed to create and automatically maintain a microclimate in the car. The system ensures the joint operation of heating, ventilation and air conditioning systems through electronic control.
The use of electronics made it possible to achieve zonal climate control in the passenger compartment. Depending on the number of temperature zones, the following climate control systems are distinguished:
· One-zone climate control;
· Two-zone climate control;
· Three-zone climate control;
· Four-zone climate control.
The climate control system has the following general arrangement :
· Climatic installation;
· control system.
Climatic installation includes structural elements of heating, ventilation and air conditioning systems, including:
· Heater radiator;
Supply air fan;
· An air conditioner consisting of an evaporator, a compressor, a condenser and a receiver.
The main elements climate control systems are:
· Input sensors;
· Control block;
· Executive devices.
Input sensors measure the corresponding physical parameters and convert them into electrical signals. Control system input sensors include:
· Outside air temperature sensor;
· Solar radiation level sensor (photodiode);
· Output temperature sensors;
Flap potentiometers;
· Evaporator temperature sensor;
· Pressure sensor in the air conditioning system.
The number of outlet temperature sensors is determined by the design of the climate control system. A footwell outlet temperature sensor can be added to the outlet temperature sensor. In a two-zone climate control system, the number of output temperature sensors is doubled (sensors on the left and right), and in a three-zone climate control system it is tripled (left, right and rear).
The flap potentiometers record the current position of the air flaps. Evaporator temperature and pressure sensors ensure the operation of the air conditioning system. The electronic control unit receives signals from sensors and, in accordance with the programmed program, generates control actions on the actuators.
Actuators include damper drives and a supply air fan motor, with the help of which a given temperature regime... The dampers can be mechanically or electrically driven. The following dampers can be used in the air conditioner design:
· Intake air damper;
· Central flap;
· Temperature control dampers (in systems with 2 or more control zones);
· Recirculation damper;
· Shutters for defrosting glasses.
The climate control system provides automatic temperature control in the vehicle interior within the range of 16-30 ° C.
The desired temperature value is set using the controls on the vehicle dashboard. The signal from the regulator goes to the electronic control unit, where the corresponding program is activated. In accordance with the established algorithm, the control unit processes the signals from the input sensors and activates the necessary actuators. The air conditioner turns on if necessary.
The modern car is a source of increased danger. The steady increase in the power and speed of the car, the density of traffic of car flows significantly increase the likelihood of an emergency.
To protect passengers in the event of an accident, they are actively developed and implemented technical devices security. At the end of the 50s of the last century, seat belts designed to keep passengers in their seats in a collision. In the early 80s were applied airbags.
The set of structural elements used to protect passengers from injury in an accident constitutes a system passive safety car. The system should provide protection not only for passengers and a specific vehicle, but also for other road users.
The most important components of the vehicle's passive safety system are:
· seat belts;
· Seat belt tensioners;
· Active head restraints;
· Airbags;
· Car body, resistant to deformation;
Emergency release battery;
· A number of other devices (rollover protection system on a convertible; child safety systems - mounts, seats, seat belts).
The modern passive safety system of the car is electronically controlled, which ensures the effective interaction of most of the components.
Control system includes:
· Input sensors;
· Control block;
· Executive devices of system components.
Input sensors record the parameters at which an emergency occurs and convert them into electrical signals. The input sensors are:
· Shock sensor;
· Switch of the seat belt buckle;
· Front passenger seat occupancy sensor;
· Seat position sensor for driver and front passenger.
On each side of the car, as a rule, two are installed shock sensor... They ensure the operation of the appropriate airbags. At the rear, impact sensors are used when the vehicle is equipped with electrically powered active head restraints. The seat belt switch locks in the use of the seat belt.
The seat occupancy sensor of the front passenger allows in the event of an emergency and front seat of the passenger to keep the appropriate airbag.
Depending on the position of the driver's and front passenger's seat, which is recorded by the corresponding sensors, the order and intensity of the use of the system components change.
Based on the comparison of the sensor signals with the control parameters, the control unit recognizes the onset of an emergency situation and activates the necessary actuators of the system elements.
The actuators of the elements of the passive safety system are:
· Airbag squib;
· Squib of the seat belt tensioner;
· Squib (relay) of the emergency battery disconnector;
· Squib of the drive mechanism of active head restraints (when using head restraints with electric drive);
· A warning lamp that indicates that the seat belts are not fastened.
Actuators are activated in a specific combination in accordance with the installed software.
ISOFIX- Isofix - child seat mounting system. Externally, child seats with this system are distinguished by two compact locks located on the back of the sled. The locks grip a 6mm bar hidden behind plugs in the base of the seat back.
Mechatronic modules are increasingly used in various transport systems.
A modern car as a whole is a mechatronic system that includes mechanics, electronics, various sensors, an on-board computer that monitors and regulates the activities of all vehicle systems, informs the user and brings control from the user to all systems. The automotive industry at the present stage of its development is one of the most promising areas for the introduction of mechatronic systems due to the increased demand and increasing motorization of the population, as well as due to the presence of competition between individual manufacturers.
If we classify a modern car according to the principle of control, it belongs to anthropomorphic devices, because its movement is controlled by a person. Already now we can say that in the foreseeable future the automotive industry should expect the emergence of cars with the possibility of autonomous control, i.e. with intelligent motion control system.
Fierce competition on automotive market forces specialists in this field to search for new advanced technologies. Today, one of the main challenges for developers is creating "smart" electronic devices that can reduce the number of road traffic accidents (RTA). The result of work in this area was the creation of an integrated vehicle safety system (SCBA), which is able to automatically maintain a given distance, stop the car at a red traffic light, warn the driver that he is making a turn at a speed higher than is allowed by the laws of physics. Even shock sensors with a radio signal have been developed, which, when the car hits an obstacle or collision, calls an ambulance.
All these electronic devices accident prevention fall into two categories. The first includes devices in the car that operate independently of any signals from external sources of information (other cars, infrastructure). They process information from an airborne radar (radar). The second category is systems whose operation is based on data received from information sources located near the road, in particular from lighthouses, which collect information about the traffic situation and transmit it via infrared rays to passing cars.
SKBA has united a new generation of the devices listed above. It receives both radar signals and infrared rays of "thinking" beacons, and in addition to its basic functions, it provides non-stop and calm movement for the driver on unregulated intersections of roads and streets, limits the speed of movement on bends and in residential areas outside the established speed limits. Like all autonomous systems, SKBA requires the vehicle to be equipped with an anti-lock braking system (ABS) and an automatic transmission.
SKBA includes a laser rangefinder that constantly measures the distance between the vehicle and any obstacle along the way - moving or stationary. If a collision is likely, and the driver does not slow down, the microprocessor gives the command to relieve pressure on the accelerator pedal and apply the brakes. A small screen on the dashboard flashes with a hazard warning. At the request of the driver, the on-board computer can set a safe distance depending on the road surface - wet or dry.
SKBA (Figure 5.22) is able to drive a car, focusing on the white lines of the road surface marking. But for this it is necessary that they are clear, since they are constantly "read" by the on-board video camera. Image processing then determines the position of the machine in relation to the lines, and the electronic system acts on the steering accordingly.
On-board infrared receivers of SKBA operate in the presence of transmitters placed at certain intervals along the carriageway. The beams propagate in a straight line and over a short distance (up to about 120 m), and the data transmitted by encoded signals can neither be drowned out nor distorted.
Rice. 5.22. Integrated vehicle security system: 1 - infrared receiver; 2 - weather sensor (rain, humidity); 3 - drive of the throttle valve of the power supply system; 4 - computer; 5 - auxiliary solenoid valve in the brake drive; 6 - ABS; 7 - range finder; eight - automatic transmission gear; 9 - vehicle speed sensor; 10 - auxiliary electrovalve for steering; 11 - accelerator sensor; 12 - steering sensor; 13 - signal table; 14 - electronic vision computer; 15 - television camera; 16 - screen.
In fig. 5.23 shows a Boch weather sensor. Depending on the model, an infrared LED and one to three photodetectors are placed inside. The LED emits an invisible beam at an acute angle to the surface of the windshield. If it's dry outside, all the light is reflected back and hits the photodetector (this is how the optical system is designed). Since the beam is modulated by pulses, the sensor will not react to extraneous light. But if there are drops or a layer of water on the glass, the conditions of refraction change, and part of the light goes into space. This is detected by a sensor and the controller calculates the appropriate wiper mode. Along the way, this device can close the electric sunroof in the roof, raise the glass. The sensor has 2 more photodetectors, which are integrated into a common housing with a weather sensor. The first is for automatic switching on headlights when it gets dark or the car enters a tunnel. The second, switches the "high" and "low" light. Whether these features are enabled depends on the specific vehicle model.
Figure 5.23. How the weather sensor works
Anti-lock braking systems (ABS), its necessary components - wheel speed sensors, electronic processor (control unit), servo valves, an electrically driven hydraulic pump and a pressure accumulator. Some early ABSs were "three-channel", ie. controlled the front brakes individually, but completely released all the rear brakes when any of the rear wheels began to block. This saved some amount of cost and design complexity, but resulted in lower efficiency compared to a full four-channel system in which each brake is individually controlled.
ABS has a lot to do with traction control system(PBS), whose action could be considered as “reverse ABS”, since the PBS works on the principle of detecting the moment when one of the wheels begins to spin rapidly compared to the other (the moment of the beginning of slipping) and giving a signal to slow down this wheel. Wheel speed sensors can be shared, and therefore the most effective way to prevent the drive wheel from spinning by decreasing its speed is to apply instant (and, if necessary, repeated) brake action, braking pulses can be received from the ABS valve block. In fact, if ABS is present, this is all that is required to provide both the PBS - plus some additional software and an additional control unit to reduce engine torque or fuel input as needed, or directly intervene in the throttle pedal control system. ...
In fig. 5.24 presents a diagram electronic system car power supply: 1 - ignition relay; 2 - central switch; 3 - storage battery; 4 - exhaust gas neutralizer; 5 - oxygen sensor; 6 - air filter; 7 - mass air flow sensor; 8 - diagnostics block; 9 - regulator idle move; 10 - throttle position sensor; 11 - throttle pipe; 12 - ignition module; 13 - phase sensor; 14 - nozzle; 15 - fuel pressure regulator; 16 - coolant temperature sensor; 17 - candle; 18 - crankshaft position sensor; 19 - knock sensor; twenty - fuel filter; 21 - controller; 22 - speed sensor; 23 - fuel pump; 24 - relay for turning on the fuel pump; 25 - gas tank.
Rice. 5.24. Simplified diagram of the injection system
One of component parts SCBA is an airbag (see Fig. 5.25.), The elements of which are located in different parts of the car. Inertial sensors located in the bumper, at the engine board, in the pillars or in the armrest area (depending on the car model), in the event of an accident, send a signal to the electronic control unit. Most modern SKBA front sensors are designed for impact force at speeds of 50 km / h. Side kicks are triggered at weaker impacts. From the electronic control unit, the signal flows to the main module, which consists of a compactly laid cushion connected to a gas generator. The latter is a tablet with a diameter of about 10 cm and a thickness of about 1 cm with a crystalline nitrogen-generating substance. An electrical impulse ignites an igniter in the "tablet" or melts a wire, and the crystals turn into gas at the speed of an explosion. The whole process described is very fast. The “average” pillow is inflated in 25 ms. The surface of the European standard airbag rushes towards the chest and face at a speed of about 200 km / h, and the American one - about 300. Therefore, in cars equipped with an airbag, manufacturers strongly advise to buckle up and not sit close to the steering wheel or dashboard. In the most "advanced" systems, there are devices that identify the presence of a passenger or child seat and, accordingly, either disconnecting or correcting the degree of inflation.
Figure 5.25 Vehicle airbag:
1 - belt tensioner; 2 - airbag; 3 - airbag; for the driver; 4 - control unit and central sensor; 5 - executive module; 6 - inertial sensors
More details on the modern automotive MS can be found in the manual.
In addition to conventional cars, much attention is paid to the creation of light vehicles (LTS) with an electric drive (sometimes they are called non-traditional). This group of vehicles includes electric bicycles, rollers, wheelchairs, electric vehicles with autonomous power sources. The development of such mechatronic systems is carried out by the Scientific and Engineering Center "Mechatronics" in cooperation with a number of organizations. LTS are an alternative to motor vehicles internal combustion and are currently used in ecologically clean areas (medical and recreational, tourist, exhibition, park complexes), as well as in retail and warehouse premises. Technical specifications prototype electric bike:
Maximum speed 20 km / h,
Drive rated power 160 W,
Rated speed 160 rpm,
Maximum torque 18 Nm,
Engine weight 4.7 kg,
Rechargeable battery 36V, 6 A * h,
Driving autonomously 20 km.
The basis for the creation of LTS are mechatronic modules of the "motor-wheel" type based, as a rule, on high-torque electric motors.
Sea transport. MS are increasingly used to intensify the work of the crews of sea and river vessels associated with the automation and mechanization of the main technical means, which include the main power plant with service systems and auxiliary mechanisms, the electric power system, general ship systems, steering devices and engines.
Complex automatic systems keeping a vessel on a given trajectory (SCS) or a vessel intended for exploration of the World Ocean on a given profile line (SCS) refers to systems that provide the third level of control automation. The use of such systems allows:
To increase the economic efficiency of sea transportation by implementing the best trajectory, vessel movement, taking into account the navigational and hydrometeorological conditions of navigation;
To increase the economic efficiency of oceanographic, hydrographic and marine geological exploration work by increasing the accuracy of keeping the vessel on a given profile line, expanding the range of wind wave disturbances, at which the required quality of control is provided, and increasing the operating speed of the vessel;
Solve the tasks of implementing the optimal trajectory of the vessel's movement when diverging from hazardous objects; to improve the safety of navigation in the vicinity of navigational hazards due to more precise control of the vessel's movement.
Integrated automatic motion control systems according to a given program of geophysical research (ASUD) are designed to automatically bring the vessel to a given profile line, automatically hold the geological and geophysical vessel on the investigated profile line, maneuver when transitioning from one profile line to another. The system under consideration makes it possible to improve the efficiency and quality of offshore geophysical surveys.
Under sea conditions, it is impossible to use conventional methods of preliminary exploration (prospecting party or detailed aerial photography), therefore the seismic method of geophysical research has become the most widespread (Fig. 5.26). A geophysical vessel 1 tows on a cable-rope 2 a pneumatic gun 3, which is a source of seismic vibrations, a seismographic streamer 4, on which receivers of reflected seismic vibrations are located, and an end buoy 5. The bottom profiles are determined by recording the intensity of seismic vibrations reflected from the boundary layers 6 different rocks.
Figure 5.26. Scheme of conducting geophysical surveys.
To obtain reliable geophysical information, the vessel must be held at a given position relative to the bottom (profile line) with high accuracy, despite the low speed (3-5 knots) and the presence of towed devices of considerable length (up to 3 km) with limited mechanical strength.
Anjutz has developed an integrated MS, which ensures keeping the vessel on a given trajectory. In fig. 5.27 presents a block diagram of this system, which includes: gyrocompass 1; lag 2; appliances navigation complexes determining the position of the vessel (two or more) 3; autopilot 4; mini-computer 5 (5a - interface, 5b - central storage device, 5c - central processing unit); punched tape reader 6; plotter 7; display 8; keyboard 9; steering gear 10.
With the help of the system under consideration, it is possible to automatically bring the vessel to the programmed trajectory, which is set by the operator using the keyboard, which determines the geographic coordinates of the turning points. In this system, regardless of the information coming from any one group of instruments of the traditional radio navigation complex or satellite communication devices that determine the position of the vessel, the coordinates of the likely position of the vessel are calculated from the data issued by the gyrocompass and the log.
Figure 5.27. Block diagram of an integrated MS for keeping a ship on a given trajectory
The control of the course with the help of the system under consideration is carried out by the autopilot, the input of which receives information about the value of the given course ψback, generated by the minicomputer taking into account the error in the position of the vessel. The system is assembled in a control panel. In its upper part there is a display with controls for adjusting the optimal image. Below, on the inclined field of the console, there is an autopilot with control levers. On the horizontal field of the control panel there is a keyboard, with the help of which programs are entered into the mini-computer. A switch is also located here, with the help of which the control mode is selected. A mini-computer and an interface are located in the basement part of the console. All peripheral equipment is placed on special stands or other consoles. The system under consideration can operate in three modes: "Course", "Monitor" and "Program". In the "Heading" mode, the set course is held using the autopilot according to the gyrocompass readings. The "Monitor" mode is selected when the transition to the "Program" mode is being prepared, when this mode is interrupted or when the transition to this mode is completed. They switch to the "Course" mode when malfunctions of a mini-computer, power supplies or a radio navigation complex are detected. In this mode, the autopilot operates independently of the minicomputer. In the "Program" mode, the course is controlled according to the data of radio navigation devices (position sensors) or a gyrocompass.
Maintenance of the ship restraint system at the ZT is carried out by the operator from the console. The choice of a group of sensors for determining the position of the vessel is made by the operator according to the recommendations presented on the display screen. At the bottom of the screen is a list of all commands allowed for this mode that can be entered using the keyboard. Accidental pressing of any forbidden key is blocked by the computer.
Aviation technology. The successes achieved in the development of aviation and space technology, on the one hand, and the need to reduce the cost of targeted operations, on the other, stimulated the development of a new type of technology - remotely piloted aircraft (RPV).
In fig. 5.28 is a block diagram of the system remote control UAV flight - HIMAT. The main component of the HIMAT remote control system is the remote control ground station. The RPV flight parameters are received at the ground point via a radio communication line from the aircraft, received and decoded by the telemetry processing station and transmitted to the ground part of the computing system, as well as to the information display devices at the ground control point. In addition, a picture of the external view, displayed with the help of a television camera, is received from the RPV board. The television image displayed on the screen of the ground workstation of a human operator is used to control the aircraft during air maneuvers, approach and landing itself. The cockpit of the ground station for remote control (operator's workstation) is equipped with instruments that provide indication of information about the flight and the state of the RPV complex equipment, as well as means for controlling the aircraft. In particular, the human operator has at the disposal of the aircraft roll and pitch control sticks and pedals, as well as the engine control stick. If the main control system fails, the control system commands are issued by means of a special console of discrete commands of the RPV operator.
Figure 5.28. HIMAT RPV remote piloting system:
carrier B-52; 2 - backup control system on the TF-104G aircraft; 3 - telemetry line with the ground; 4 - RPV HIMAT; 5 - telemetry lines with RPV; 5 - ground station for remote piloting
Doppler ground speed and drift angle meters (DPSS) are used as an autonomous navigation system providing dead reckoning. Such a navigation system is used in conjunction with a heading system that measures the course with a vertical sensor that generates roll and pitch signals, and an onboard computer that implements the dead reckoning algorithm. Together, these devices form a Doppler navigation system (see Figure 5.29). To increase the reliability and accuracy of measuring the current coordinates of the aircraft, DISS can be combined with speed meters
Figure 5.29. Diagram of a Doppler navigation system
The miniaturization of electronic elements, the creation and serial production of special types of sensors and indicator devices that reliably operate in difficult conditions, as well as a sharp reduction in the cost of microprocessors (including those specially designed for cars) created conditions for the transformation of vehicles into MS of a fairly high level.
High-speed magnetic levitation vehicles are a prime example of a modern mechatronic system. So far, the only commercial transport system of this kind in the world was put into operation in China in September 2002 and connects Pudong International Airport with downtown Shanghai. The system was developed, manufactured and tested in Germany, after which the train cars were transported to China. The guiding track, located on a high overpass, was manufactured locally in China. The train accelerates to a speed of 430 km / h and covers 34 km in 7 minutes (the maximum speed can reach 600 km / h). The train hovers over the track, there is no friction on the track, and the main resistance to movement is provided by the air. Therefore, the train is given an aerodynamic shape, the joints between the cars are closed (Figure 5.30).
To prevent the train from falling on the track in the event of an emergency power outage, it has powerful storage batteries, the energy of which is enough to smoothly stop the train.
With the help of electromagnets, the distance between the train and the guide track (15 mm) during movement is maintained with an accuracy of 2 mm, which makes it possible to completely eliminate the vibration of cars even on maximum speed... The number and parameters of the supporting magnets are trade secrets.
Rice. 5.30. Magnetic suspension train
The transport system on a magnetic suspension is completely computer controlled, since at such a high speed a person does not have time to react to emerging situations. The computer also controls the acceleration and deceleration of the train, taking into account the turns of the track, so the passengers do not feel discomfort when acceleration occurs.
The described transport system is distinguished by high reliability and unprecedented precision in the execution of the traffic schedule. Over the first three years of operation, over 8 million passengers were transported.
Today, the leaders in maglev technology (an abbreviation for magnetic levitation used in the West) are Japan and Germany. In Japan, the maglev set a world record for the speed of rail transport - 581 km / h. But Japan has not yet advanced further than setting records, trains run only on experimental lines in Yamanashi prefecture, with a total length of about 19 km. In Germany, Maglev technology is being developed by Transrapid. Although the commercial version of the Maglev has not caught on in Germany itself, the trains are operated at the Emsland Proving Ground by Transrapid, which was the first in the world to successfully implement a commercial version of the Maglev in China.
As an example of already existing transport mechatronic systems (TMS) with autonomous control, one can cite a robotic machine from VisLab and the laboratory of machine vision and intelligent systems of the University of Parma.
Four robotic cars have covered an unprecedented path for autonomous vehicles of 13 thousand kilometers from Italian Parma to Shanghai. This experiment was intended to be a tough test for the intelligent autonomous driving system TMS. It was also tested in city traffic, for example, in Moscow.
Robot cars were built on the basis of minibuses (Figure 5.31). They differed from ordinary cars not only in autonomous control, but also in pure electric traction.
Rice. 5.31. VisLab autonomous vehicle
On the roof of the TMC, solar panels were located to power critical equipment: a robotic system that turns the steering wheel and presses the gas and brake pedals, and computer components of the car. The rest of the energy was supplied by electrical outlets during the trip.
Each robot car was equipped with four laser scanners in the front, two pairs of stereo cameras looking forward and backward, three cameras covering a 180-degree field of view in the front "hemisphere" and a satellite navigation system, as well as a set of computers and programs that allow the machine to make decisions in certain situations.
Another example of an autonomously controlled mechatronic transport system is the RoboCar MEV-C robotic electric vehicle from the Japanese company ZMP (Figure 5.32).
Figure 5.32. RoboCar MEV-C robotic electric vehicle
The manufacturer positions this TMC as a machine for further advanced developments. The autonomous control device includes the following components: a stereo camera, a 9-axis wireless motion sensor, a GPS module, a temperature and humidity sensor, a laser rangefinder, Bluetooth, Wi-Fi and 3G chips, and a CAN protocol that coordinates the joint operation of all components ... The RoboCar MEV-C measures 2.3 x 1.0 x 1.6 m and weighs 310 kg.
The modern representative of the mechatronic transport system is the transcooter, which belongs to the class of light vehicles with an electric drive.
Trans-scooters are a new type of transformable multifunctional land vehicles for individual use with an electric drive, mainly intended for people with disabilities (Figure 5.33). The main distinguishing feature of the transcooter from other land vehicles is the ability to pass through flights of stairs and the implementation of the principle of multifunctionality, and therefore transformability in a wide range.
Rice. 5.33. The appearance of one of the samples of a transcooter of the "Kangaroo" family
The propeller of the transcooter is made on the basis of a mechatronic module of the "motor-wheel" type. The functions and, accordingly, the configurations provided by the "Kangaroo" family of trans scooters are as follows (Figure 5.34):
- "Scooter" - movement at high speed on a long base;
- "Chair" - maneuvering on a short base;
- "Balance" - movement while standing in the gyrostabilization mode on two wheels;
- "Compact-vertical" - movement while standing on three wheels in the gyro-stabilization mode;
- "Curb" - overcoming the curb right away while standing or sitting ( individual models have an additional function "Oblique curb" - overcoming the curb at an angle of up to 8 degrees);
- "Ladder up" - climbing the steps of the stairs forward, sitting or standing;
- "Ladder down" - descent along the steps of the stairs forward, while sitting;
- "At the table" - low seating position, feet on the floor.
Rice. 5.34. Basic configurations of a transcooter on the example of one of its variants
The trans scooter includes, on average, 10 compact high-torque electric drives with microprocessor control. All drives are of the same type - valve motors direct current controlled by signals from Hall sensors.
To control such devices, a multifunctional microprocessor control system (CS) with an on-board computer is used. The architecture of the transcooter control system is two-tier. The lower level is servicing the drive itself, the upper level is the coordinated operation of the drives according to a given program (algorithm), testing and monitoring the operation of the system and sensors; external interface - remote access. As a top-level controller ( on-board computer) uses the PCM-3350 from Advantech, made in the PC / 104 format. The lower-level controller is a Texas Instruments specialized microcontroller TMS320F2406 for controlling electric motors. The total number of low-level controllers responsible for the operation of individual units is 13: ten drive controllers; steering head controller, which is also responsible for indicating the information displayed on the display; controller for determining the residual capacity of the storage battery; battery charge and discharge controller. Data exchange between the on-board computer of the transcooter and peripheral controllers is supported via a common bus with a CAN interface, which allows you to minimize the number of wires and achieve a real data transfer rate of 1 Mbit / s.
Tasks of the on-board computer: control of electric drives, service of commands from the steering head; calculation and display of the residual battery charge; solving the trajectory problem for moving up the stairs; the possibility of remote access. The following individual programs are implemented via the on-board computer:
Acceleration and deceleration of the scooter with controlled acceleration / deceleration, which is personally adapted for the user;
A program that implements the algorithm for the operation of the rear wheels when cornering;
Longitudinal and transverse gyro stabilization;
Overcoming the curb up and down;
Up and down stairs
Adaptation to the size of the steps;
Identification of staircase parameters;
Wheelbase changes (from 450 to 850 mm);
Monitoring of scooter sensors, drive control units, battery;
Emulation based on the readings of the parking radar sensors;
Remote access to control programs, changing settings via the Internet.
The transcooter has 54 sensors that allow it to adapt to the environment. Among them: Hall sensors built into the valve electric motors; absolute angle encoders that determine the position of the components of the transcooter; resistive steering wheel sensor; infrared distance sensor for parking radar; inclinometer, which allows you to determine the inclination of the scooter while driving; accelerometer and angular rate sensor for gyro stabilization control; radio frequency receiver for remote control; a resistive linear displacement transducer for determining the position of the chair relative to the frame; shunts for measuring the motor current and the residual capacity of the battery; potentiometric speed adjuster; strain gauge weight sensor to control the weight of the device.
The general block diagram of the CS is shown in Figure 5.35.
Rice. 5.35. Block diagram of the SU by a trans-scooter of the "Kangaroo" family
RMC - absolute angle encoders, DX - Hall sensors; BU - control unit; ZhKI - liquid crystal indicator; MKL - left wheel motor; MCP - right wheel motor; BMS - Power Management System; LAN - port for external connection of the on-board computer for programming, configuration, etc .; T - electromagnetic brake.
There is a point of view that mechatronic technologies include technologies of new materials and composites, microelectronics, photonics, microbionics, laser and other technologies.
However, at the same time, there is a substitution of concepts and, instead of mechatronic technologies, which are implemented on the basis of the use of mechatronic objects, these works deal with the technology of manufacturing and assembling such objects.
Most scientists nowadays believe that mechatronic technologies only form and implement the necessary laws of executive movements of computer-controlled mechanisms, as well as aggregates based on them, or analyze these movements to solve diagnostic and prognostic problems.
In machining, these technologies are aimed at ensuring accuracy and productivity that cannot be achieved without the use of mechatronic objects, the prototypes of which are metal-cutting machines with open CNC systems. In particular, such technologies make it possible to compensate for errors that arise due to oscillation of the tool relative to the workpiece.
However, preliminary it should be noted that mechatronic technologies include the following stages:
Technological problem statement;
Creation of a model of the process in order to obtain the law of the executive motion;
Development of software and information support for implementation;
Supplementing the information management and design base of a typical mechatronic object that implements the proposed technology, if necessary.
An adaptive method for increasing the vibration resistance of a lathe.
In the conditions of using a variety of cutting tools, machined parts of complex shape and a wide range of both machined and tool materials, the likelihood of self-oscillations and the loss of vibration resistance of the machine's technological system increases sharply.
This entails a reduction in processing intensity or additional capital investment in the technological process. A promising way to reduce the level of self-oscillation is to change the cutting speed during processing.
This method is quite simple to implement technically and has an effective impact on the cutting process. Previously, this method was implemented as a priori regulation based on preliminary calculations, which limits its application, since it does not allow taking into account the variety of causes and variability of the conditions for the occurrence of vibrations.
Adaptive systems for controlling the cutting speed with on-line control of the cutting force and its dynamic component are much more effective.
The mechanism for reading the level of self-oscillations during machining with a variable cutting speed can be represented as follows.
Suppose that when processing a part with a cutting speed V 1, the technological system is in conditions of self-oscillation. In this case, the frequency and phase of oscillations on the machined surface coincide with the frequency and phase of oscillations of the cutting force and the cutter itself (these oscillations are expressed in the form of crushing, waviness and roughness).
When moving to the speed V 2, oscillations on the machined surface of the part relative to the cutter during the subsequent revolution (when processing "on the track") occurs with a different frequency and synchronism of oscillations, that is, their phase coincidence is violated. Due to this, in conditions of processing "on the trail", the intensity of self-oscillations decreases, and high-frequency harmonics appear in their spectrum.
With the passage of time, natural resonance frequencies begin to dominate in the spectrum and the process of self-oscillations intensifies again, which requires a repeated change in the cutting speed.
It follows from what has been said that the main parameters of the described method are the amount of change in the cutting speed V, as well as the sign and frequency of this change. The effectiveness of the effect of changing the cutting speed on the processing performance should be assessed by the duration of the auto-oscillation recovery period. The larger it is, the longer the reduced level of self-oscillations remains.
The development of a method for adaptive control of cutting speed involves the simulation of this process based on a mathematical model of self-oscillation, which should:
Take into account the dynamics of the cutting process;
Consider tracking processing;
Adequately describe the cutting process under conditions of self-oscillation.
