Research On Nonlinear Control Of Attitude Tracking For Servo Platform Of Parallel Mechanism

Strong bearing capacity,high stiffness and high accuracy make parallel mechanism servo system(PMSS)popularly applied.As nonlinear control theory advances,higher requirements are put forward for the control performance of PMSS.This paper focus on the development of the PMSS,and the working principle,structure design,motion analysis and control scheme of the platform are described in detail.The nonlinear factors affecting performance and its control strategies are studied.According to the task requirements,the control system was designed and verified in kind,which provided theoretical basis and practical experience for the application of PMSS.Firstly,as the main design scheme of PMSS,the working principle,the technical index and the structural design of the system is introduced in detail.Based on the analysis of platform kinematics,the nonlinear mathematical model and each actuator model are established based on Lagrange equation,which provides a model reference for the design of control method.Secondly,the discrete control scheme of PMSS is determined out of its special structure.The classical control is used to design the three channel control loops of the platform,and its regulator is designed and the parameters are tuned.Considering the multi-axis motion coupling of the platform,a method of joint simulation based on ADAMS and MATLAB to simulate and verify the coupling effect between the platform pitch and roll channels.Thirdly,the effects of load inertia,hinge friction and multi-channel coupling interference on the tracking accuracy of the platform are analyzed.A synchronous sliding mode variable structure control(SMVSC)is proposed,which combines sliding mode variable structure control(SMVSC)with synchronous error compensation,ensure the control accuracy and robustness of the platform.The simulation results verify the feasibility and superiority of the SMVSC.Finally,the software and hardware design requirements of the system are analyzed up to actual task requirements.And a high performance platform controller composed of dual-core ARM is designed,and the specific selection of platform actuator and sensor is listed.The motion control software of PMSS and the monitoring software of host computer are developed.The design based on correlation coupling error is verified by the prototype test.