Research On 6R Manipulator Trajectory Planning And Control System Based On FPGA

The existing industrial robot control system is mainly composed of control module and driving module which take PC + motion control card or dedicated controller as the core. As a controller, the field programmable gate array FPGA is widely used in various kinds of control system because of its technology advantages of running speed, internal program parallel running, customizing various kinds of circuit and field upgraded. The research object is 6R manipulator in this paper and the problem of trajectory planning and control system based on FPGA is studied.Firstly, the structural diagram of manipulator and the connecting rod parameters are acquired by using the D-H parameters method to model. Through establishing kinematic equations, the forward kinematics is analyzed and it is focused on studying traditional algebraic method and double quaternions in the problem of kinematics inverse solution, and the optimal solution of the inverse is obtained by shortest distance principle. Then polynomial interpolation and parabolic transition linear interpolation in joint space trajectory planning and straight line and curve trajectory planning in the Cartesian coordinate space are introduced.Secondly, through the design of 6R manipulator control system, the main control chip and its configuration chips in the hardware system are selected and the basic circuit is designed. Considering control convenience and lower cost, the system is open loop system and is driven by step motor. In order to improve the control effect the stepper motors are with self-locked brake and the stepper motor driver choose Toshiba TB6560 as the core driver. Analyzing the function of each module of the software system, and considering the advantage of FPGA in the soft core processor, the SOPC system is constructed based on Nios Ⅱ processor to process the kinematics inverse solution problem. The trajectory planning module completed the parabolic transition linear interpolation trajectory planning adopted by the control system, the SDRAM control module sent the joint angular velocity discrete values in the process of trajectory planning to FPGA external memory chips, and the PWM pulse driver module realized trapezoid curve algorithm by using the joint angular velocity and controlled the stepping motor to get the desired trajectory.Finally, using Robotics Toolbox for Matlab simulation platform to model 6R manipulator, and calling the Toolbox functions to solve the problem of forward kinematics and inverse kinematics, and traditional algebraic method about inverse kinematic solution is made by programming script language. At the same time, utilizing script language and the Toolbox to verify the problems in the joint space and the Cartesian coordinate space trajectory planning. And parabolic transition linear interpolation trajectory planning is implemented by Modelsim simulation tool.