Design of modular joint controller based on FPGA with software/hardware co-design methods

In order to impove the performance of robot joint control, a modular joint controller was developed based on a field programmable gate arrays (FPGA) with software/hardware co-design methods. In the controller, sensors information acquisition and current vector control were programmed in VHDL, which is a stardard hardware discription language, to improve the bandwidth, and the period of current control loop is 50 μs. In addition, the robot joint control law was calculated in Nios II processor by C language with the period of 200 μs. The top-down design method was presented by the design of vector control, whose calculater time lasts for 3.48 μs, and some modulars date flow graphs were given out, such as coordinate transfermation and PI controller. In the end, the joint controller was applied in 7 degrees of freedom (DoF) robot. The results show that the joint positions as well as the motor torques are tracking well. Moreover, the controller is insensitive to the robot configurations.