Design of electronic cam control system based on servo-motor

BAI Shu-hong
（Department of Electrical Engineering， Chengdu Electromechanical College， Chengdu 610027，China）

Abstract： Aiming at the disadvantages of conventional mechanical cam：difficult to machine and maintenance，esay to wear，an advanced electronic-cam control system was designed. The electronic cam used BECKHOFF servo motion control experimental platform which consisted of embedded PC，digital servo drives，permanent magnet synchronous servo motor，ball screw linear platform and so on. A three-loop control mode（position loop，speed loop and current loop）was employed. The servo-motor's position and speed instructions were calculated to simulate the real cam's track by inner virtual shaft's displace and electronic-cam's table，which drive the ball screw move straightly back and forth. To ensure the existence and continuation of peed curve and acceleration curve，a five polynomial was adopted as interpolation function in the rising and falling phases，which improved kinematical performance. The experiment results indicate that when using the electronic cam plan，screw can get the position precisely，and react rapidly. Tracking error was controlled within 0.005 mm. It proves that using the electronic cam to replace the traditional mechanical cam is feasible.
Key words： servo motion；electronic cam；path interpolation；virtual principal axis