Research On Servo Control System Of Parallel-Serial Opto-Electronic Stable Platform

Since the inception of stable platform, the frame-type of serial mechanism in stableplatform was widely applied because of its good characteristics of simple structure, largework space and flexible movement. In contrast, parallel stable platform has overwhelmingadvantages as good stiffness of structure, large carrying capacity, high precision in positionand compact conformation etc. However, both of serial and parallel stable platform haveunsolvable shortcomings such as the conflict between work space and carrying capacity andso on. In this paper, the study did comprehensive investigation of serial and parallel hybridplatform and combined both advantages of them. Based on the prototype of the parallel-serialopto-electronic stable platform developed in our lab, the study in this paper was conducted inresearch fields of kinematics, dynamics, random drift of fiber-optic gyroscope (FOG), controlalgorithm, realization of servo system and so on. Main contributions and innovations of thispaper were described as following:1、Kinematics analysis of the serial-parallel electro-optical stable platform applying vectormethod and rotation matrix method. Using3D modeling software UG and multibody dynamicssimulation software ADAMS, we constructed3D simulation model of the stable platform. Basedon derived kinemics model and3D model, the study detailedly investigated coupled relationshipbetween output rolling, pitching and yawing angle, which were exported by the platform.Additionally we processed simulation for kinemics model and3D model of the parallel-serialopto-electronic stable platform. Through compared with data from experimental results, kinemicsmodel and3D model were further proved as efficient and accurate models.2、Constructing dynamics model of the parallel-serial opto-electronic stable platformbased on Lagrange algorithm and principle of virtual work. Lagrange algorithm is mostsuitable for controller design and practice, since it can solve complicated dynamics equationsby simplest way and represent structural dynamics equation as closed form. In this paper, weanalyzed the kinetic energy of different parts of the stable platform and construct dynamicsmodel for the stable platform. Based on principle of virtual work, we analyzed generalized force, which supplied theory basis for further research and practice of control method.3、Constructing random drift model of FOG based on temporal series and applyingKallman filtering to restraint random drift. After analysis of characteristics of random drift ofFOG, we used experimental data to construct ARMA model for random drift. Random driftwas efficiently restrained by applying Kallman filtering in random drift model. Throughtesting data were analyzed, it was confirmed that random drift was dealt with by filteringaccording to ARMA model and good results of filtering were achieved during experiments.4、Designing a nonlinear adaptive controller to improve dynamics model. In this paper,different parameters in dynamics model were analyzed in detail. Considering friction, loaddisturbance and kinetic parameters error existing in real system, we separated unmodeleddynamics parameters, friction parameters and effects of load disturbance from dynamicsmodel and obtained linear expressions for parameters to be identified in dynamics model.Lyapunov method was applied for the design of nonlinear adaptive controller. We separatelysimulated our proposed controller and computed torque controller under the conditions oftracking high speed and low speed. Through comparing the experimental results, we can givethe conclusion that our proposed nonlinear adaptive controller has much better control effectsthan traditional computed torque controller under both of conditions.5、Building software and hardware of servo system and constructing experimentalplatform. The contribution of this part of work is to supply an efficient simulated platformwhich has similar conditions with the actual environment to investigate and test relatedtechnologies in the parallel-serial opto-electronic stable platform. We applied the newproposed nonlinear adaptive controller to the serial and parallel opto-electronic stableplatform. Experimental results proved the correctness of proposed theoretical analysis in thispaper and the efficiency of designed control system.