Active Suspension Control Of Multi-axle Off-road Vehicle Based On Preview Front Road Information

The preview active suspension relies on preview sensors to realize the digital terrain in front of the vehicle.It can eliminate the time lag of existing active suspension’s adjustment,solve the problems of low speed,poor ride comfort and handling stability on complex road surface of emergency rescue vehicle,and improve vehicle mobility.Based on the national key R&D project "Research on Key Technologies of Special Chassis and Suspension for High-mobility Emergency Rescue Vehicles(Including Fire-fighting Vehicles)"(Project No.2016YFC0802902),the online high-speed topographic survey in front of vehicle based on multi-sensor data fusion and the control of preview active suspension are mainly discussed.The research contents and work are as follows:Firstly,aiming at the requirements of preview range,measurement accuracy and sampling frequency,Ibeo-Lux 2010 LIDAR is selected as the preview sensor,and its working mode and installation angle are studied.Secondly,an online scanning scheme of vehicle’s front terrain based on multi-sensor data fusion is proposed.LIDAR collects the point cloud of the terrain,combining the real-time vehicle position and attitude information acquired by GPS/INS integrated navigation system.The paper completes the transformation from instantaneous laser beam coordinate system to WGS84 geodetic coordinate system.Thirdly,road elevation extraction of vehicle trajectory position.Based on the experimental platform of the vehicle’s front terrain scanning system,the 3D point cloud of the road surface is obtained.The point cloud filter in PCL library is used to post-process the point cloud,and the Inverse Distance Weighted interpolation is used to obtain the road elevation information of the vehicle trajectory position.Fourthly,the terrain mesh is refined.Because of the insufficient scanning frequency ofLIDAR,the accuracy of road elevation is low.Using the advantage of fractal theory to describe natural phenomena,the fractal feasibility of pavement elevation curve is validated firstly,and then fractal interpolation algorithm is used to interpolate the curve,which improves the resolution of terrain.Fifthly,an AHP-LQG active suspension controller is designed based on the road roughness level in front of the vehicle.AHP is used to calculate the weight coefficients in the comprehensive performance evaluation index of LQG controller under different pavement roughness grades.The weight coefficients are selected according to the on-line measurement of pavement roughness grade.Finally,the control simulation model of active and passive suspension system is established in MATLAB/SIMULINK,which verifies that the AHP-LQG active suspension controller and the refinement of pavement grid based on fractal interpolation can improve the effectiveness of vehicle ride comfort and handling stability.