Kim Hubert, Asbeck Alan T
Mechanical Engineering Department, Virginia Tech, Blacksburg, VA 24061, USA.
HardwareX. 2020 Oct 22;8:e00153. doi: 10.1016/j.ohx.2020.e00153. eCollection 2020 Oct.
A direct drive motor is one of the simplest mechanisms that can be used to move a mechanical joint. In particular, a brushless direct current (BLDC) motor with no gearing produces a low parasitic torque due to its backdrivability and low inertia, which is ideal for some applications such as wearable systems. While capable of operating with a higher power density than brushed motors, BLDC motors require accurate position feedback to be controlled via vector control at slow speeds. The MotorWare library from Texas Instruments (TI), which is designed to run with a C2000 microcontroller, is written to run BLDCs. However, the code was written to run the motor continuously with an incremental encoder and requires further engineering to be used at low speeds such as in an exoskeleton. In this paper, we present the design of an elbow exoskeleton that can be used for haptic feedback. We provide instructions to build the exoskeleton hardware, custom code to modify software provided by TI so that a motor can provide a controlled torque at low speeds, code to enable the microcontroller to communicate with a computer for high-level commands and data storage, and also provide an overview of how alternate motors could be used with this software setup.
直接驱动电机是可用于驱动机械关节的最简单机构之一。特别是，无齿轮的无刷直流（BLDC）电机由于其可反向驱动性和低惯性而产生低寄生转矩，这对于诸如可穿戴系统等某些应用来说是理想的。虽然BLDC电机能够以比有刷电机更高的功率密度运行，但在低速时需要精确的位置反馈才能通过矢量控制进行控制。德州仪器（TI）的MotorWare库旨在与C2000微控制器一起运行，用于驱动BLDC电机。然而，该代码是为使用增量编码器使电机连续运行而编写的，要在诸如外骨骼等低速情况下使用还需要进一步的工程设计。在本文中，我们展示了一种可用于触觉反馈的肘部外骨骼的设计。我们提供了构建外骨骼硬件的说明、用于修改TI提供的软件的定制代码，以便电机能够在低速时提供受控转矩、使微控制器能够与计算机通信以进行高级命令和数据存储的代码，并且还概述了如何将替代电机与这种软件设置一起使用。
