Yen Shih-Hsiang, Tang Pei-Chong, Lin Yuan-Chiu, Lin Chyi-Yeu
Department of Mechanical Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan.
Ubiqelife Technology Corporation, Jhubei City, Hsinchu 302, Taiwan.
Sensors (Basel). 2019 Jul 18;19(14):3171. doi: 10.3390/s19143171.
Robot arms used for service applications require safe human-machine interactions; therefore, the control gain of such robot arms must be minimized to limit the force output during operation, which slows the response of the control system. To improve cost efficiency, low-resolution sensors can be used to reduce cost because the robot arms do not require high precision of position sensing. However, low-resolution sensors slow the response of closed-loop control systems, leading to low accuracy. Focusing on safety and cost reduction, this study proposed a low-gain, sensorless Brushless DC motor control architecture, which performed position and torque control using only Hall-effect sensors and a current sensor. Low-pass filters were added in servo controllers to solve the sensing problems of undersampling and noise. To improve the control system's excessively slow response, we added a dynamic force compensator in the current controllers, simplified the system model, and conducted tuning experiments to expedite the calculation of dynamic force. These approaches achieved real-time current compensation, and accelerated control response and accuracy. Finally, a seven-axis robot arm was used in our experiments and analyses to verify the effectiveness of the simplified dynamic force compensators. Specifically, these experiments examined whether the sensorless drivers and compensators could achieve the required response and accuracy while reducing the control system's cost.
用于服务应用的机器人手臂需要安全的人机交互；因此，此类机器人手臂的控制增益必须最小化，以限制操作期间的力输出，这会减慢控制系统的响应速度。为了提高成本效益，可以使用低分辨率传感器来降低成本，因为机器人手臂不需要高精度的位置传感。然而，低分辨率传感器会减慢闭环控制系统的响应速度，导致精度降低。着眼于安全性和成本降低，本研究提出了一种低增益、无传感器的无刷直流电机控制架构，该架构仅使用霍尔效应传感器和电流传感器进行位置和转矩控制。在伺服控制器中添加了低通滤波器，以解决欠采样和噪声的传感问题。为了改善控制系统过度缓慢的响应，我们在电流控制器中添加了动态力补偿器，简化了系统模型，并进行了调谐实验以加快动态力的计算。这些方法实现了实时电流补偿，并加快了控制响应速度和精度。最后，我们在实验和分析中使用了一个七轴机器人手臂来验证简化动态力补偿器的有效性。具体而言，这些实验检验了无传感器驱动器和补偿器在降低控制系统成本的同时，是否能够实现所需的响应速度和精度。
