- 學位論文
自走機器人之追蹤避障與無線充電
Toward the Collision Avoidance of an Autonomous Robot and Wireless Power Transfer
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摘要
本文利用共振推挽式轉換器，實現無線充電，並將此功能與輪型機器人做結合；而輪型機器人的避障策略則採用人工勢場法，並利用雷射測距儀擷取環境資訊，實現避障。 共振推挽式轉換器將開關操作在零電壓(Zero Voltage Switching, ZVS)狀態，來減少轉換器在開關切換時所造成能量的損失，而實現ZVS電路最常見的技巧則是利用共振現象。而共振槽(resonant tank)擁有很低的阻抗，可以將電流(能量)鎖於此槽，然而，開關的切換頻率會影響儲存於共振槽能量的多寡，當切換頻率與共振頻率一樣時，則能100% 不讓共振槽內的能量流失。而Mazzilli 電路利用交錯偶合二極體(cross-coupled diode)，來控制開關的頻率與關閉時機，藉以簡化複雜的開關訊號電路。 而人工勢場法則是將環境視為一虛擬勢能場，其中目標點產生引力場，障礙物則產生斥力場，在合力場中由高勢能往低勢能移動，以此機制決定機器人的移動路徑與速度，以避開障礙物並抵達目標點。 實驗中包含無線能量傳輸電路模擬與燈泡負載下的實驗，鉛酸電池無線充電實驗，最後結合避障功能，使輪型機器人可以閃避障礙物，抵達車庫內進行充電。
並列摘要
In this thesis, a push-pull resonant converter is used to realize the wireless charging system, combined with wheeled robot. And the way of avoiding obstacle is artificial potential filed method. We used laser range finder to complete this avoiding obstacle function. The push-pull resonant converter makes the switch operate at zero voltage, which known as “Zero-Voltage Switching, ZVS”. When the switches operate under this condition, it can minimize the switching losses. The most common technique for achieving zero-voltage switching is to utilize the resonant phenomena. The resonant tank in the push-pull resonant converter has a very low series impedance, this can make the current(power) locked in the tank. However, the switching frequency has a great influence on the transfer efficiency. While the switching frequency is the same as the resonant frequency, the switching frequency would not reduce the power transfer. And the Mazzilli circuit utilize cross-coupled diode to control the switching frequency and the timing of closing the gate, without complicated active control circuit. The artificial potential filed method assumed that the environment is a virtual potential energy field. The target will generate an attractive potential field and obstacles will cause repulsive potential field to the robot. And the combination of attractive and repulsive potential field will determine the velocity of robot, making the robot move to the target and avoid the obstacles. The experiments include the simulation of wireless power transfer, wireless power transfer with bulb loadings, wireless charging of acid-lead battery, and the combination of obstacle avoidance and wireless charging, making the wheeled robot avoid obstacle and autodock in the garage for charging battery.
參考文獻
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