摘要

隨著醫療科技快速發展，社會逐漸邁向高齡化，電動輪椅為較嚴重神經肌肉病變之功能性障礙者、老年人或慢性病患者主要日常生活行動輔助工具。目前國內、外電動輪椅主要包括：永磁式直流有刷（PMDC）馬達、開迴路控制器、機械傳動裝置及電瓶。

因此本研究目的為探討PID對PMDC馬達之速度回饋控制表現，來提供最佳化差速控制器設計，以改善傳統電動輪椅之效率、穩定性。本研究定目標：(1) Matlab/Simulink軟體建立PID控制PMDC馬達速度模型，(2) 模擬分析電動輪椅馬達平地運動、斜坡運動不同負載時之暫態及穩態系統表現，電動輪椅馬達做轉彎時兩輪差速比較，(3) 閉迴路控制應用PMDC馬達改變速度的控制表現，並建立PMDC馬達理想差速控制參數作為發展設計電動輪椅之閉迴路差速數位控制器。

結果顯示PID控制器經由公式計算而得知 =0.5， =8， =0.08之解析參數值，與本研究模擬不同負載、速度下，電流及速度安定時間短、電流及速度上升時間快不至於產生電流最大超越量更能追隨電動輪椅的變速關係、減少電動輪椅暴衝結果相符。因此，本研究電動輪椅馬達應用在平地運動、斜坡運動及轉彎運動不同負載、不同速度下：（1）開迴路控制PMDC馬達啟動時馬達電流隨著速度增加而上升越高，PMDC馬達停止時馬達電流隨著速度增加而下降越多；（2）閉迴路控制PMDC馬達啟動與停止時馬達速度不會受負載影響，電流隨著負載增加。PMDC馬達加速與減速時結果相同於PMDC馬達啟動停止時；（3）開迴路控制電動輪椅轉彎時左右兩輪差速隨著速度增加而上升，左右兩輪差速隨著負載增加而下降；（4）閉迴路控制電動輪椅轉彎時左右兩輪差速不受負載影響，根據上述使用閉迴路控制理想PID參數Kp=0.5、 Ki=8、 Kd=0.008相較於開迴路控制電動輪椅穩定性佳。

建議未來實際場試來改善電動輪椅控制器的功能。控制法則方面，可考量使用適應控制、可變結構控制來做差速控制，進而設計安全性的電子差速控制器。

Abstract

Powered wheelchairs (PW/Cs) are the major mobility-aided device for persons with moderate/severe physical disabilities, chronic diseases, and the elderly. The PW/C system includes: PMDC motor, open-loop controller, gear box, battery. This research was to design a digital differential speed controller with velocity feedback for improved efficiency and stability of PW/Cs.

The specific aims include：(1) to develop and establish PID speed control on PMDC motor speed model by using Matlab/Simulink software; (2) at flat and inclined surfaces and different speed and loading conditions, investigate the closed-loop and open-loop PMDC motor current and speed responses including transient and stable states also the motor responses for differential speed on left and right motors in the turning; (3) investigate the effect of speed accelerations and decelerations on the closed-loop and open-loop PMDC motor current and speed responses .

The parameter values of Kp =0.5 and Ki =8 and Kd =0.008 are illustrated to be optimal in the PID control on PMDC motor speed, which is agreed to the analytic results. At flat and inclined surfaces and different speed and loading conditions, (1) the PMDC motor shows that the initial current at the open-loop is more rapidly increasing than that of at the closed-loop with PID during the starting state, but more rapidly decreasing during the stopping state; (2) the PMDC motor with PID control shows that the motor speed is not influenced by the different loadings during the starting and stopping states, but the motor current is positively proportional to the loading. Atthe
acceleration and deceleration conditions, the PMDC motor with PID control has demonstrated the same current and speed responses resulted from the starting and stopping states. At the turning conditions, (1) the open-loop control shows that the differential speed of right and left motors is increasing with the PW/C speed, but is decreasing with the increase of external loading; (2) the PID closed-loop control sows that the differential speed of right and left motors is not influenced by the external loading. Therefore, the PID parameter with Kp =0.5 and Ki =8 and Kd =0.008 has demonstrated to be useful in the improved design of closed-loop controller for the efficiency and stability of the PW/C.

The future works are recommended to conduct field testing of the controller on PW/Cs and to investigate other control methods such as adaptive and variable structure control.

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