本文之研究目的在於建立一個完善的煞車策略分配,藉由控制多碟片安全性煞車與電子式煞車系統,達到安全又舒適地煞車效果,並且確立手輪馬達驅動的電動輪椅在上坡啟動的安全性。文中先介紹手輪馬達式電動輪椅動力鏈系統的組成,動力鏈系統將手輪馬達、馬達驅動控制器、鋰鐵電池與多碟片安全性煞車整合於一車輪內,而成為一動力輪,如此則僅需要一普通輪椅車架搭配兩個動力輪,即可結合成一手輪馬達式電動輪椅,再介紹無刷直流馬達運轉原理與驅動原理,使用方波驅動令馬達起步再搭配簡化弦波電流控制,以驅動控制手輪馬達式電動輪椅。 此手輪馬達式電動輪椅煞車主要分為兩種,一種為機械式煞車系統,如本文所採用之多碟片安全性煞車,此煞車原理為使用彈簧壓住玻璃纖維煞車薄片,產生煞車力,並且藉由馬達抵抗彈簧力控制煞車力,另一種為電子式煞車系統,此種煞車系統利用馬達之反電動勢,藉由位置感測器調整六個絕緣柵雙極電晶體開關,達到輸出反力矩的效果,本文中電子式煞車可分為三種不同的方法,分別為回充電力式煞車,反灌式煞車,三相短路煞車。其中上坡起步使用重力感測器判斷坡度,並且藉由煞車與馬達啟動策略,達到上坡不下滑平順起步的效果,此手輪馬達式電動輪椅採用霍爾感測器測量位置,以閉迴路轉速控制馬達轉速。 本研究所提出的控制策略藉由電腦模擬馬達運轉與煞車之動態響應,並且和實際馬達之轉速、馬達三相電流做實驗比較,建立一個完善的煞車策略分配,達到安全又舒適地煞車效果。
This paper presents a comprehensive braking and hill start assist control strategy. By controlling multi-disc brake and motor electric brake, the strategy can establish an uphill start assist control to achieve safe and comfortable braking effect. This paper firstly introduces a rim-motor-powered wheelchair’s power chain system with integrating rim motor, motor drive, motor controller, lithium-ion battery, and multi-disc brake, which allows making a rim-motor-powered wheelchair by simply combining an ordinary wheelchair frame and two powered wheels. Next, the paper describes the brushless DC electric motor’s operation principle and driving principle, which uses a square wave to start the rim motor and a simplified sinusoidal current control to drive the rim-motor-powered wheelchair. The rim-motor-powered wheelchair’s brakes are divided into two systems, the mechanical brake system and the electronic brake system. In this paper, we exhibit the mechanical brake system with introducing the multi-disc brake discs, which uses the principle of the spring pressed glass fiber sheet to generate braking force and control the braking force by the motor’s position. On the other hand, the electronic brake system uses the motor’s back-EMF by controlling the insulated gate bipolar transistor switch to produce brake torque. The electronic brake system can be divided into three different braking methods, regenerative braking, plug braking, and dynamic braking. This paper also describes the uphill start assist control using gravity sensors to determine the slope and control the motor and the brake, which can achieve a smooth start on uphill without slip. In this research, by comparing the simulation and experiment results, we can confirm the effect of braking and hill start assist control strategy of a rim-motor-powered wheelchair, and establish a comprehensive braking and hill start assist control strategy, to achieve safe and comfortable braking effect.