新型手輪馬達電動輪椅雙動力輪與控制策略的整合

Abstract

本文研究目的在於開發並整合雙動力輪與控制策略，而形成新型手輪馬達電動輪椅。文中先介紹手輪馬達電動輪椅之研發歷程、目前無刷直流手輪馬達的特性、以及手輪馬達電動輪椅動力鏈系統之設計概念，其將手輪馬達、整合型電磁煞車、霍爾效應感測器、馬達驅動控制器與鋰鐵電池，結合成電動輪椅之動力輪，故一般輪椅車架只需加裝兩個動力輪即可成為電動輪椅，再經由無刷直流馬達運轉原理與驅動方式，選擇使用簡化弦波電流控制之方式驅動手輪馬達電動輪椅。 手輪馬達電動輪椅控制系統架構中著重手輪馬達速度控制，其策略使用緩起動速度控制、閉迴路速度控制、三相短路煞車控制與磁粉煞車控制，達到手輪馬達穩定的動態速度控制，並增加斷電式電磁煞車，提升手輪馬達電動輪椅在靜止時的安全性，以及斷電式電磁煞車之節能控制策略，有效地節省20 %的操作電流。 電動輪椅控制器之硬體架構分為上、下控制器，使用微控制器與整合式馬達驅動晶片做開發，參照國家標準CNS規範來設計，上控制器負責人機介面接收訊號、雙輪差速計算控制與安全限制條件，左右兩輪各別的下控制器透過防止EMI的設計規範以及電路板最小化設計，相較於第一版下控制器其體積縮小比例為79 %，尺寸為105 mm × 35 mm × 35 mm，因此更增加產品化的特色，下控制器負責接收速度命令配合簡化弦波驅動與煞車驅動完成雙手輪馬達速度控制。經過實驗測試驗證，本新型手輪馬達電動輪椅驅動控制系統已能實現穩定的速度控制，並達到斷電式電磁煞車的節能效果且具有產品化的基本功能。

The aim of this study is to develop and integrate dual power wheels and control strategy for a novel powered wheelchair driven by rim motors. First, the historical and technological backgrounds of the powered wheelchair will be introduced, and the concept of designing a power train for a powered wheelchair will be illustrated. This power train contains two sets of rim motors, electromagnetic brakes, Hall-effect sensors, motor drives, and lithium iron phosphate batteries. Integration of these components establishes the system of power wheels. Installation of the dual power wheels on a commercial wheelchair frame turns a manually driven wheelchair into a powered wheelchair. The control system focuses on the speed control of the powered wheelchair driven by rim motors, to which a simplified sinusoidal current waveform is applied. The strategy is to improve the rim motor by developing a control system consisting of a soft-starting, dual-wheel synchronous speed control, a three-phase short-circuit brake, and a powder brake that will maintain the safe and stable operation of the wheelchair. An automatic lock by an electromagnetic brake is also added for the consumer’s safety when the wheelchair is at rest. Power management of braking also provided a twenty percent savings in energy compared to the devices without any electromagnetic braking power management. The powered wheelchair controller is divided into an upper controller and a lower controller; both are researched and developed with microchips and motor driver ICs according to the Chinese National Standards (CNS). The upper controller is responsible for the human interface, dual-wheel differential speed control system, and safety restrictions. The lower controller receives commands from the upper controller and uses a simplified sinusoidal current waveform and brake control strategy to drive dual rim motors. The lower controller is designed to prevent electromagnetic interference and to minimize the size of the printed circuit board. Compared with the previous printed circuit board, the system volume is reduced by 79%, to a smaller size of 105 × 35 × 35 mm3. The experimental results indicate that the control system of the novel powered wheelchair driven by rim motors is stable, and the electromagnetic brake also achieves energy savings. Therefore, this product can be expected to be commercialized and to appear in shop windows soon.