6 D0f Attitude Control Key Technology Research Platform

Multi degree of freedom platform for vibration and pointing control is one of the key techniques for complex optomechatronics system. The6DOF platform have a highlight advantage of ability to heavy load and commonality, so widely used for aerospace to deep diving now. The research works of this dissertation are based on a major project of Chinese national high technology development plan (863). In view of the difficulty to several key technological problems in the application of the six degrees of freedom Stewart platform, which includes kinematic, calibration, dynamic and automatic control theory, which were validated by the experiments of the real platform. The main works can be described as follows.The basic relationship of6DOF platform, position and posture of move platform to struts length are analysed. A numerical approach to solving the forward kinematic problem by Newton iterative method will be presented here. Using the Jacobian matrix and first order Jacobian matrix can determine an incremental Cartesian displacement of the move platform, associated with an incremental set of strut displacements. The workspace and velocity Envelope evaluation for the6DOF platform deduced. Analyzing the resource of error, we get some related spectra map, top plat position and posture error corresponding with every error resource respectively. We presents a new accurate method for calibration of the6DOF platform of symmetry construct kinematic parameters by a gyro instrument.The dynamic model of6DOF parallel manipulator is developed using the principle of virtual work. The actuating force of each electromechanical actuators in different position and posture is obtained, which has built for the simulation analysis of the dynamic coupling between the six comprised subsystems. We focuses in the modeling of an electromechanical linear actuator to be used in a heavy load six-degrees-of-freedom platform application by experimental result of frequency response. After obtaining the structure of model, transfer function parameters can be derived by system identification.Control system is the core of6DOF platform as a effectively electromechanical system, included hardware (synchronous motors, servo drivers and electromechanical linear actuators) and software(communication protocol and control strategy). Based on existing hardware system, especial considering the characteristic of single strut system, control strategy of the platform system are discussed. In addition, considering about the characteristics of nonlinearity, time varying, and multivariable coupling of the system, Narendra model reference adaptive scheme of Lyapunov Second Method is developed, which can enhance the control performance for system stabilization time. The simulated results show that the control system achieves a better tracking performance and the control system has strong robustness.