Study On Adaptive Attitude Control And Stable Passability Of Longitudinal Driving On Steep Slope Clay Pavement With Walking Chassis

The terrain in mountainous areas is mostly irregular road surfaces and slopes with large angles.When traditional machinery is driving or operating on steep slopes,the chassis pitch Angle is too large,the driver’s perspective and visual field are poor,and the judgment of the surrounding environment is reduced,resulting in low efficiency of operation.Even due to the unstable position of the center of mass,there will be serious safety accidents such as roll over and rollover.Compared with the traditional chassis structure,the walking chassis is more complex and flexible.It can adjust the driving attitude of the whole machine by relying on the lifting or stretching of the legs,change the pitch Angle and the position of the center of mass of the chassis,and cope with the complex road surface.This paper mainly studies the adaptive control and stable passage of the walking chassis longitudinal driving attitude.The research object is the walking mechanical hydraulic chassis facing the steep slope clay road.A control strategy of adaptive adjustment of the chassis driving attitude with high stability is proposed,and the pitch Angle and the position of the center of mass of the chassis are taken as the optimization objectives for adaptive adjustment.The virtual prototype model of walking chassis and slope pavement was established.The static and dynamic stability of the chassis is analyzed,and the conditions of chassis overturning are obtained.According to ZMP(zero moment point)criterion,the method of dynamically adjusting the position of the center of mass and increasing the anti-overturning of the whole machine is obtained.Establish the adaptive control system of the chassis: The main control strategy is PID control strategy,by adding fuzzy control,the PID control has the function of self-tuning parameters,to enhance its ability to cope with the change of working conditions and resist external interference,further optimize the control performance of PID controller,fuzzy PID control system in Simulink,complete the joint simulation model,Provide simulation conditions for chassis adaptive control.Adaptive control is carried out on the pitch Angle of the chassis,combined with the fuzzy PID control system for the adaptive control of the pitch Angle of the chassis,in the relatively stable range,the chassis always keeps the horizontal state when uphill;According to the dynamic centroid position adjustment method,combined with the fuzzy PID control system,the centroid position of the chassis is adjusted in real time,so that when the chassis is driving on the steep slope clay road,the centroid position is kept at the zero torque point.The vertical velocity of the center of mass before and after attitude adjustment,the pitch Angle of the chassis and the horizontal displacement of the center of mass were analyzed to verify the effectiveness of the fuzzy PID control strategy on the 27%(15 °)、36%(20 °)and 47%(25 °)steep slope clay road.The results show that the adaptive adjustment of the chassis pitch Angle can automatically adjust the chassis pitch Angle to the level,so that the driver has a more comfortable Angle of view,and increase the driver’s judgment of the surrounding;The adaptive adjustment of the centroid position of the chassis can effectively increase the anti-overturning and stable passability of the chassis when it is vertically uphill.In the simulation,the maximum climbing slope of stable passability reaches 47%(25 °),and part of the pitch Angle of the chassis is reduced.The fuzzy PID control strategy can effectively control the two kinds of driving attitude,which provides some ideas and basis for the attitude adjustment of the walking chassis on the complex road surface.