Test approach for experimental investigation of vehicle electric power-assisted steering system
Technical field
The invention belongs to the Vehicle Engineering apparatus testing method, be specifically related to vehicle electric servo steering system method of testing.
Background technology
Electric boosting steering system (EPS:Electric Power Steering System) is different from traditional hydraulic power-assist steering system (HPS:Hydraulic Power Steering System) and electric-controlled hydraulic servo steering system, it does not need complicated mechanical and hydrostatic control, have energy-saving and environmental protection and improve plurality of advantages such as automobile operation performance, receive many scholars' concern, become the focus of Hyundai Motor steering research and development.
In EPS design and development process, need several below aspects to study: in (just under the Vehicular turn moment actual change rule situation) under the vehicle actual operating state, according to some parameters of vehicle determine assist characteristic curve, the different control strategies of comparison the control effect, the steering parameter is carried out matching Design etc.
If can provide a kind of test method of carrying out electric boosting steering system test, research under the real vehicle driving conditions of simulating to promote the EPS progress of research greatly.
Chinese patent 92 233 334.9 adopts Hookean spring that the steering gear output terminal is loaded; Chinese patent 02 220 571.3 is used hydraulic mechanism and mechanical mechanism simulation steering gyrus positive force and damping force.Above-mentioned two patents are ignored the influence of ground tangential force to tire cornering characteristics when EPS being carried out correlation test research; Ignore load change to the influence of tire cornering characteristics and the influence of tyre moment; Ignore the effect of suspension.These simplification make method of testing can not reflect that load, speed, road surface condition variation and tire characteristics change the influence to the EPS system performance.
Summary of the invention
Technical matters to be solved by this invention provides a kind of load, speed, road surface condition variation and tire characteristics of reflecting and changes the method for testing to the influence of EPS system performance.This method of testing can be used for investigating load, speed, road surface condition variation and tire characteristics and change to the EPS Effect on Performance, so that the assist characteristic rule of EPS, control strategy and the EPS instability Mechanism of EPS are studied.
For solving the problems of the technologies described above, the invention provides a kind of test approach for experimental investigation of vehicle electric power-assisted steering system, concrete steps are as follows.
1. adjust and load counterweight
Load counterweight according to the testing requirements adjustment, make the load that is loaded into the steering front-wheel meet carload and distribute characteristics.
2. adjust the crawler belt friction factor
According to the requirement of test road pavement attachment coefficient, track surface is carried out spray treatment, make the track surface roughness reach the coefficient of road adhesion of testing requirements.
3. the tire positional parameter is adjusted
By the position of adjustment suspension and the position of tire central plane the tire positional parameter is adjusted, the tire positional parameter is equated with the tire positional parameter of test vehicle.
4. tire rotational speed adjustment
The rotating speed of power input device motor is adjusted in requirement according to running velocity, and the circumference tangential velocity of tire is equated with the running velocity of requirement.
5. the exciting type is adjusted
A vibrator is set below tire, according to the impact effect of different brackets road surface to vehicle, adjusts excited frequency and amplitude, simulated roadway is to the impact effect of wheel.
6. data collection and analysis
According to different test objectives, gather relevant sensor signal, and carry out conversion of signals, amplification and graphic presentation, preservation processing.
Specifically, adopt this vehicle electric servo steering system research method of testing to carry out following correlation test research to EPS.
1, road surface impact of interference test
Tested EPS control device is installed on the test-bed, adjust the weight mass that loads in the case, make 1/4 of the maximum steering drag of steering drag automobile up to specification, and adjust the road shocks effect of the amplitude of vibrator vibration and frequency simulated roadway to steering front wheel, in vehicle speed range, test at interval by 5~20km/h speed of a motor vehicle.In the manual uniform rotation bearing circle of both direction, in total travel sensation work whether smoothly, reach bearing circle continuously friction arranged; When bearing circle goes to arbitrarily angled stopping, the output terminal inertial delay phenomenon that do not have.This test is the anti-road shocks jamming performance that is used for investigating controller.
2, side force of tire interference test
Tested device is installed on the test-bed, system works is normal, bearing circle transfixion when bearing circle is in the straight-line travelling position, apply shock load at steering gear output terminal (steering front wheel one side), time is no more than 10 milliseconds, and data acquisition system (DAS) writes down variation, the testing crew of steering wheel angle when impacting automatically and controls the variation of bearing circle moment and the variation of the dynamo-electric stream of assisted electric.Apply shock load in the opposite side of steering front wheel then, data acquisition system (DAS) writes down variation, the testing crew of steering wheel angle when impacting automatically and controls the variation of bearing circle moment and the variation of the dynamo-electric stream of assisted electric.
Computer software is drawn steering wheel angle one impulsive force curve automatically according to the test figure of front.Investigate the EPS controller to being applied to the interference free performance of side direction perturbed force on the deflecting roller.
3, parameter perturbation interference test
Tested EPS control device is installed on the test-bed, change the loaded load quality, adjust tyre rotation speed, change the crawler belt friction factor, the dynamo-electric stream of investigation assisted electric under these parameter perturbation situations, steering wheel torque variation characteristic judge the performance of EPS controller under parameter perturbation situation.
Test method provided by the invention can more accurately be simulated by the force-bearing situation to wheel steering system in the laboratory, can reflect of the influence of factors such as carload, pavement behavior, wheel alignment parameter, suspension system, tire characteristics, car speed, so that carry out the research of EPS correlation test to EPS.
Description of drawings
Fig. 1 is vehicle electric servo steering system research experimental apparatus for testing synoptic diagram;
Fig. 2 is experiment process figure;
1 bearing circle among the figure; 2 turn to input shaft; 3 steering wheel torque sensors; 4 speed reduction units; 5 gears; 6 tooth bars; 7 drag links; 8 assisted electric machines; 9 controllers; 10 electromagnetic clutchs; 11 electromagnetic clutch control signals; 12 vehicle speed sensor; 12 ' vehicle speed signal; 13 ' steering wheel torque signal; 14 engine rotational speed signals; 15 turn to output shaft; 16 desirable power-assisted electric currents; 17 springs; 18 resistance servomotors; 19 power input systems; 20 torque measurement roller traies; 21 numerical control electrohydraulic servo test systems; 22 data collecting cards; 23 computing machines; The dynamo-electric stream of 24 ' assisted electric signal; 25 ' vehicle front-wheel weight signal; 26 steering wheel angle signals; 26 angular transducers; 27 ' displacement signal; 28 load chargers; 29 tire suspension systems;
Embodiment
The present invention is further detailed explanation below in conjunction with accompanying drawing and example.
The present invention and test unit as shown in Figure 1 are used.
Data collecting card 22 is inserted in the slot of computing machine 23, gathers the multiple sensor signal, and carries out corresponding conversion process.The sensor signal of gathering has: vehicle speed signal 12 ', bearing circle dtc signal 13 ', the dynamo-electric stream of assisted electric signal 24 ', vehicle front-wheel weight signal 25 ' and steering wheel angle signal 26 ', displacement signal 27 '.
Vehicle speed signal 12 ' measured by vehicle speed sensor 12, this sensor is positioned on the axletree.This signal is one of key signal of determining the desirable booster torquemoment of motor.
Bearing circle dtc signal 13 ' measured by the torque sensor signal 3 that is positioned on the steering axle, it can measure the level of torque that is applied in driver's steering procedure.This signal is an another key signal of determining the desirable booster torquemoment of motor.
Assisted electric electromechanics stream signal 24 ' measured by the external hanging type Hall current sensor, it can measure the size of the dynamo-electric stream of assisted electric of electric boosting steering system, and one and the proportional voltage signal of current of electric are provided.
Vehicle front-wheel weight signal 25 ' measured by the force sensor signals in the numerical control electrohydraulic servo test system 21, expression is loaded into the carload of Vehicular turn front-wheel.
Angular transducer 26 is positioned on the bearing circle 1, is used to measure driver's rotational angle, to data collecting card 22 provide driver's angular signal 26 '.
Displacement transducer 27 is positioned on the exciting head of numerical control electrohydraulic servo test system 21, gathers the distance that steering front wheel moves up and down, to data collecting card 22 provide displacement signal 27 '.
The running velocity signal that computing machine 23 is gathered according to data collecting card, the calculation engine tach signal transmits engine rotational speed signals 14 by data collecting card to EPS controller 9, makes the EPS can operate as normal.
EPS controller 9 gather torque signal 13 from steering wheel torque sensor 3 ', vehicle speed signal 12 ', think the size and Orientation of power-assisted electric current 16 according to rational assist characteristic curve decision assisted electric mechanism, according to the engine rotational speed signal 14 of data collecting card output and the control signal 11 that produces, the control electromagnetic clutch disconnects, combination.
After on-test, the signal sampling analytic system starts automatically.The PC receive direction dish torque signal of sampling system, steering wheel angle signal, vehicle speed sensor signal, current sensor signal, displacement transducer signal, load transducer signal.In case steering wheel rotation, tire is done corresponding deflection around stub, and steering resisting moment changes along with the variation of steering wheel angle, until reaching following maximal value that can reach of this driving cycle.Increase along with steering wheel angle, the steering-wheel torque signal increases gradually, when surpassing the power-assisted threshold value, the electric-control system instruction motor begins power-assisted, by the EPS system controller according to bearing circle dtc signal, Vehicle Speed, table look-up according to the assist characteristic curve and to determine the working current size of motor, the i.e. desirable power-assisted electric current of assisted electric machine.Current signal and desirable power-assisted electric current that controller is constantly gathered the assisted electric machine compare, and adopt suitable control strategy to make electrical motors arrive desirable power-assisted current value.When one turn to end cycle after, sampling analysis system can be drawn out steering-wheel torque, corner and the power-assisted electric current change curve with wheel weight, the road conditions of travelling and Vehicle Speed.And then analyze power-assisted effect, the assist characteristic curve of electric boosting steering system, the situation of change of aligning torque.
Accompanying drawing 2 has provided the process flow diagram of this experimental study method of testing.Being described as follows of process flow diagram:
1, selects test event according to test objective.
2,, adjust wheel alignment parameter according to research contents; Select the crawler belt of different coefficients of friction and require to adjust the quality that loads counterweight in the case according to the Surface of Trial Pavement grade according to complete vehicle quality.
3, according to content of the test, the travelling speed of adjusting wheel by the controller of varying-speed motor reaches testing requirements.
4,, the impact effect of tire is adjusted the amplitude and the frequency of vibrator according to different pavement grades according to testing requirements.
5,, select different test types according to test objective.
Test 1: road surface impact of interference test;
Test 2: input, output characteristics test;
Test 3: power-assisted current characteristics test;
Test 4: side force of tire interference test;
The development test of test 5:EPS assist characteristic;
Test 6: low speed returns positive attribute testing;
Test 7: return the positive damping attribute testing at a high speed.
6, print trial curve, trial curve is carried out correlation analysis, thereby make the judgement of some science.
7, off-test.
This electric boosting steering system experimental study method of testing can be simulated the parameter perturbation of real vehicle load, speed when travelling, embody that road shocks disturbs and the side force of tire interference to the influence of controller, the control effect of access control strategy.Can reduce simultaneously the danger and the research cost of the examination of direct entrucking road.