超低速、高可靠空间二维转台伺服控制系统设计

为了实现空间二维转台在轨高可靠性和低成本的应用,同时具有低速平稳运动、高精度跟踪和360°全范围连续工作等能力,建立了以FPGA芯片为核心的步进电机矢量控制系统,通过电流正弦细分表的PWM斩波调节实现步进电机的128细分精准控制,以21位光电编码器作为位置反馈,谐波减速器作为传动机构,实现了二维转台的开环控制、速度实时调整跟踪控制、最优路径规划控制和运动超时保护等功能,并对场效应管开关时间对斩波频率和最大细分数的影响进行了分析。实验结果表明,四轴的跟踪精度3σ下优于0.005°,速度稳定性小于5%,伺服控制带宽大于4 Hz,具有连续过零能力。该控制系统可以简化硬件设计、增加软件适用性,适用于超低速运动,满足二维转台对伺服控制系统的指标要求。

Design of servo control system for ultra low speed and high reliability space two dimensional turntable

In order to realize the high reliability and low-cost application of the space two-dimensional turntable in orbit, as well as the ability of low-speed smooth motion, high-precision tracking and 360° full range continuous operation, a vector control system of stepper motor based on FPGA chip is established. The 128 subdivision precision control of stepping motor is realized by PWM chopping adjustment of current sine table. A 21 bit photoelectric encoder used as position feedback and a harmonic reducer used as mechanism drive to realize open-loop control, real-time speed adjustment and tracking control, optimal path planning control and motion timeout protection. The influence of MOSFET on chopping frequency and maximum subdivision is analyzed. The experimental results show that the tracking accuracy of the two axes is better than 0.005° at 3σ, the speed stability is less than 5%, and the servo control bandwidth is more than 4 Hz, and it has the ability of continuous zero crossing. The control system can simplify the hardware design, increase the applicability of software, more suitable for ultra-low speed motion, and meet the requirements of two-dimensional turntable for servo control system.