本論文主題在跑步機驅動系統中，設計無外加感測轉速元件之轉速偵測電路，馬達運轉時，因為碳刷與換相片的切換造成電樞電流出現漣波，因此我們從直流馬達的反電動勢中可直接擷取切換時產生的漣波電壓訊號，將訊號處理成方波，計算頻率後可求得馬達轉速，達到系統閉迴路控制，此外因馬達電流和負載有正比關係，也可利用電流訊號，經過濾波處理分析出跑者之負載量、步數、步幅等運動行為 系統功能包括馬達速度控制、跑步皮帶之斜坡度偵測與控制、LCD訊號與電源傳輸界面、過電流與異常電壓等保護、按鍵功能選擇等，皆在單晶片微控器PIC16F877完成控制運算，其他跑者的步數、步幅、距離也在其中計算完成。 根據實驗結果，由光編碼器量測之轉速驗証得知，檢測轉速電路量測的轉速和實際馬達轉速非常接近，誤差小，且閉迴路控制之性能也可適用，此系統又可供跑者分析負載變化及運動行為，比一般傳統感測元件更為簡單。 本論文所設計之無感測器控制系統不用外加任何感測元件或更改額外機構，直接並聯於運轉中之直流馬達的電源端，量測轉速並做控制，對於產業界為相當省功、省時、省力之實務性的做法，且具有相當高的應用價值。 The subject in this thesis is to design the circuit for detecting motor speed without velocity sensor in treadmill driver system. When a DC motor is functioning, the current ripples in the motor are generated while the carbon brush contacts with the commutator segments. Furthermore, the voltage signals of the ripples can be extracted straightforwardly from the counter-electromotive force in a DC motor. After signal processing and frequency computing, the signal frequency and the motor speed are obtained consequently. The next step is to implement the closed loop velocity control system. Because of the motor current is proportional to the load, the current signals provide information about the runner’s gait events just like a stride, step, foot-contact and foot-off events. The system includes motor speed controller, detector and controller of the treadmill belt’s gradient, interface between LCD panel and microcontroller, protector for over current or abnormal voltage and function select keyboard. All these components are implemented using the PIC16F877 microcontroller. The experimental results demonstrate that the rotation speed measurement of the system circuit is extremely close to that of the rotor encoder, and the closed loop control system is also well performed. Compared with the traditional devices, the system supplies a simpler method to analyze the variation of motor loading and the runner’s gait events. The control system is directly connected to the power line of the DC motor to detect and control the motor speed without velocity sensor or extra mechanism. Therefore, the proposed system is absolutely practical for industrial and commercial applications.
