High performance algorithm realization on FPGA for stepper motor controller

Abstract

This paper focuses on studying the dynamic characteristics of stepper motors. Based on the relation of velocity and torque of stepper motors, a novel algorithm of velocity profile for stepper motor is proposed for straightforwardly realizing on field programmable gate array (FPGA). Missing steps have been a major issue while applying stepper motors on various critical situations. The reason of causing missing steps of stepper motors is due to the high velocity slewing. To alleviate this difficulty, a closed loop control may be applied, but introducing a complex design and more cost than open loop one. If open loop is chosen, the velocity profiles for various applications must be considered to avoid the missing step effect. There are three widespread used profiles: parabolic, trapezoidal, and S-curve profiles. For carrying out the operation of calculating the tedious profiles, a recursive velocity profile algorithm is presented along with a control parameter beta, where 0 < beta < 1, beta=1, and 1 < beta < 2, are corresponding to S-curve, trapezoidal, and parabolic profiles respectively, then this algorithm can be realized on a compact hardware. Thus, a high speed and high precision of stepper motor controller can be achieved by combining a system on chip (SOC) with this hardware.