Study Of Automatic Leveling System For Vehicle-borne Radar Antenna Based On Parallel Support Mechanism

This paper presents a 4-DOF parallel manipulator (4-SPS(PS)) and 6-DOF Parallel manipulator (Stewart platform) as the support mechanism of motion and static base for automatic leveling system of vehicle-borne radar antenna, and the kinematics and dynamics of parallel manipulator are analyzed. On this basis, the two different application situations are considered which real-time leveled by the motion base and heavy-load by the static base, the automatic leveling Platform Control System Design and automatic leveling closed-loop control are simulated by the sliding mode variable structure control with observer and the generalized forecast control of variable structure based on the stochastic forecast model are simulated comparably. Details are as follows:Based on the analysis of the leveling characteristics of traditional leveling platform, the article uses the four-DOF parallel manipulator (4-SPS(PS)-type)and 6-DOF Parallel manipulator (Stewart platform) as the support mechanism of motion and static base for automatic leveling system of radar antenna, and the characteristics of posture, kinematics, dynamics and other aspects are analyzed and researched. Based on the SimMechanics, the parallel support mechanism is put to test. The multi-channel hydraulic servo system of Parallel support mechanism which of the static base for automatic leveling system of vehicle-borne radar antenna(Stewart platform)is decoupled by the linear feedback method of decoupling. The sub-chain driver force and the driver speed for parallel support mechanism of motion and static base are analyzed. It is for the lectotype of driver. Under the conditions of open loop, the leveling properties of the support mechanism of motion and static base for automatic leveling system of vehicle-borne radar antenna are analyzed.According to the high degree of accuracy, high frequency band and fast response of the automatic leveling system of vehicle-borne radar antenna, this article uses electro-hydraulic servo system as the driver set of the support mechanism of motion and static base for automatic leveling system of vehicle-borne radar antenna. Based on the in-depth analysis of electro-hydraulic servo system structure, this article established a mathematical model of non-symmetrical cylinder valve-controlled hydraulic servo system. The electro-hydraulic servo system open-loop frequency response characteristics of static base for automatic leveling system of vehicle-borne radar antenna is analyzed, and the temporal response characteristics and frequency response band width of electro-hydraulic servo system which of motion base for automatic leveling system of vehicle-borne radar antenna is analyzed. According to using the feedback correcting method of speed/acceleration, this article broadens electro-hydraulic servo system which of motion base for automatic leveling system of vehicle-borne radar antenna bandwidth.On the basis of the anti-problem of static base for automatic leveling system kinematics and the characteristic test of automatic leveling system single-hydraulic electro-hydraulic servo system, It Suggested that the static base for automatic leveling system of vehicle-borne radar antenna and control system stability are designed by the sliding mode variable structure control. In order to solve the parameter uncertainty of automatic leveling system and inhibit the buffeting phenomenon of sliding mode variable structure control, this paper proposes that the static base for automatic leveling system of vehicle-borne radar antenna is designed by the sliding mode variable structure control with observer. Thereby it can effectively improve the automatic leveling-platform performance, reduce the steady-state error of automatic leveling system, and inhibit the buffeting phenomenon of sliding mode variable structure control.The response frequency of Control System and the randomness of operating environment is two impact of the performance of motion base for automatic leveling system of vehicle-borne radar antenna. The control system of response frequency is determined mainly by the external equipment (frequency response of hydraulic servo system, electrical systems, etc.), speed and the control strategy. In actual work process, hydraulic servo system response shall have a certain frequency bands. Blindly improving the frequency response of hydraulic servo system and improving sensitivity of electric system is not advisable. By using generalized predictive variable mechanism control strategy of a random interference signal, establishes random road spectrum as a random variable sequence of generalized forecasting, introduces auxiliary control value to combine the generalized predictive control with variable structure control ,determines the relationship of speed, response frequency of control system and random road spectrum, achieves the motion base for automatic leveling system real-time leveling.