On The Stabilized Platform Based On 2-DOF Spatial Parallel Robot

Transportation carriers such as vehicles,ships,and aircrafts are greatly affected by the external environment during operation,which may cause bumps,oscillations,etc.,which causes the navigation,detection,and stable aiming equipment on the transportation carriers to not work properly,and the stable platform can pass real-time detection and active compensation of the carrier's position and posture to achieve isolation and disturbance,so as to ensure that the equipment installed on the carrier has a stable working environment under the effect of external interference.The 2-UPS/U parallel mechanism studied in this thesis is a typical parallel mechanism with few degrees of freedom.It has the advantages of high rigidity,strong bearing capacity and easy to control.It can realize free rotation in two directions around a spatial fixed point and has a good prospect of development and application.Based on the structural design and kinematics analysis of the 2-UPS/U parallel mechanism,this thesis designs and builds the experimental prototype and its control system,then verifies the research results of this thesis through a series of motion experiments..The main work of the thesis is as follows:Firstly,the design scheme of 2-UPS/U parallel stable platform is proposed,the machine and structure of the platform is designed,and its kinematics is analyzed.According to the design requirements,the parts are designed and the prototype model of the stable platform is established.Then,the virtual prototype of the mechanism is established,and the preliminary kinematic simulation analysis is carried out to verify the rationality of the structural design.Furthermore,the kinematic analysis of the mechanism is carried out.The inverse kinematics solution model and velocity Jacobian matrix of the mechanism are obtained by the coordinate change method.Then,the Newton Iterative method based on velocity Jacobian matrix is used to establish the forward kinematics solution model.By analyzing the influencing factors of the attitude workspace,the reachable attitude workspace is solved by the boundary search method.Secondly,based on multi axis motion controller and Visual C++6.0,the software and hardware control system of stable platform is designed and developed,and a trajectory planning method based on optimized trapezoid curve is proposed.First,the hardware facilities of the control system are selected and configured,including industrial computer,motion control card,electric cylinder,sensor and other components.Then,based on the idea of modularization,the human-computer interface is developed by using MFC,and different functional modules are packaged to realize the motion control of the stable platform.In addition,the trajectory planning method based on the optimized trapezoid curve is used to plan the trajectory of the upper platform and the correctness and effectiveness of path planning are verified by the joint simulation of numerical analysis software and virtual prototype software.Finally,a prototype is built and a series of experiments such as closed-loop attitude adjustment,attitude tracking and passive compliance were carried out.The attitude closed-loop control method is designed based on the inclination sensor,and the attitude adjustment experiment of the platform is carried out,which verifies the rationality of the hardware and software system design and the effectiveness of the closed-loop control method.The correctness of the trajectory planning method is verified by the attitude tracking experiments of single axis motion and compound motion.In addition,based on the force sensing system composed of joint force sensor,the collision self leveling function and passive compliance control function are designed and developed,and their effectiveness is verified by experiments.