Research Of Open Motion Control System Based On QNX

Two kinds of motion controllers based on ASIC and special processor are common in engineering applications. Though these controllers can satisfy basic control requirements, they have limits in firmware upgrades and extensions, let alone their high price. Considering these problems, we design an open real-time motion control system based on QNX. Both hardware and software structure of the control system are designed. The proposed control system has the characteristics of versatility, ease of use and scalability. The design process mainly consists of the following three parts.In the first part, we design the hardware interface of the control system. FPGA is chosen as the core of hardware system. Its plenty I/O ports are used as the interfaces of signals’input and output. Also, the A/D circuit, D/A circuit and encoder interface circuit are designed. Finally, we verify the accuracy of hardware circuits working sequence via simulation.The second part is focused on various motion control algorithms. Mathematical models of AC servo motors and DC servo motors are established. Motion control algorithms based on mathematical models of AC and DC servo motors are simulated using SIMULINK of MATLAB. We improved the control algorithm taking into account of influences encountered during the practical application. In this paper, we used three kind of control algorithm:PID control algorithm, PID plus feedforward control algorithm and differential forward PID plus feedforward control algorithm. We analyze the advantages and disadvantages of three kinds of algorithm by simulation, Differential forward PID plus feedforward control algorithm is selected because it satisfies the time and control effect demands of practical application.The third part introduces the overall structure of QNX system, and explains the reason we choose QNX system for motion control. Then we compile the human machine interaction interface of motion control system using PhAB. Finally, the trapezoidal and S-curve acceleration and deceleration processes are analyzed in QNX system.We evaluate the real-time motion control system via experiments, and analyze the actual running graphs. At last, we summarize the deficiencies during the research and point out the potential improvements in the future.