全數位式史都華平台控制器之設計與開發

The Design of a Full Digital Controller for the Stewart Platform

陳至誠(Scott Chen)

指導教授 ： 曾百由

國立臺北科技大學/機電學院/機電整合研究所/碩士(2008年)

摘要

史都華平台在1965年由英國人史都華(D. Stewart)提出，其後有許多有關平台結構、平台運動演算法以及各種應用研究陸續被發展出來。史都華平台在虛擬實境與動感模擬的應用系統中是非常重要的部份，例如用在汽車、捷運、船舶和飛機等互動式駕駛模擬訓練系統，甚至教育與娛樂之應用方面。在控制器上也有許多人投入研究並獲得不錯的成果，但是大都延續以前的架構，未見有突破性的做法，以致平台運動效能的改善雖有進展，但仍無法呈現系統可達之較佳效能。平台控制器和驅動器的研究上也已經有許多人投入心力並獲得成果，但是目前所有驅動器仍然只有類比驅動的方式，尚未出現數位驅動方式。所以本研究設計一個以數位訊號處理器為核心之嵌入式平台控制器，作為史都華平台運動控制器，並將傳統的類比式伺服驅動器予以數位化，完成一個全數位化之史都華平台控制器，讓整合的模擬系統能夠因控制及驅動器的改良而獲得更高的運動效能，更加精簡的系統架構，而且能達到更高的電能使用效率。
數位驅動器主要是採用普遍運用於切換式電源轉換器之脈波寬度調變(PWM)技術，由控制器輸出PWM訊號直接驅動MOSFET驅動器，以取代傳統由數位類比轉換器、運算放大器和功率放大器所組成的類比伺服驅動器。使用MOSFET驅動器之數位伺服驅動器，可有效減少零件而大幅縮小系統體積、降低系統成本、增加系統穩定度、免除類比驅動器所需要的調整步驟以及將所有校正參數全部融入韌體程式中。另外，由於從控制器到伺服閥不必經過類比元件，訊號延遲縮短至一百奈秒以內，使得本研究所完成的全數位式史都華平台控制器之系統響應比起以往發展之所有控制器，包括IPC等，都要來得優異。

關鍵字

動感模擬 ； 虛擬實境 ； 史都華平台 ； 數位式控制器 ； 數位式驅動器 ； 切換式電源 ； 脈波寬度調變 ； 數位訊號處理器 ； MOSFET 驅動器 ； 伺服驅動器

並列摘要

Stewart platform was proposed in 1965 by D. Stewart. There are a lot of researches on the structure of the platform, the movement calculation of the platform and similar applications are developed later on. The Stewart platform plays a very important role in the virtual reality and motion simulation systems such as interactive driving simulation training systems for the automobile, rapid mass transportations, ships, airplane, and applications on education and entertainment.
There are many people contributed their efforts in the platform controller with servo driver and have good achievement. Most of servo driver structures are similar and no creative innovation has been found, such that the system performance of the platform is still limited by the performance of controller and driver. Currently, existing servo drivers available in the market are analog type until a digital type of driver is proposed by this thesis.
This research has designed and developed an embedded digital signal processor based platform controller and digital servo driver and completed with a full digital Stewart platform controller. This full digital platform controller can make the system to reach a better performance with less power consumption than all the previous controllers.
The digital servo driver has adopted pulse width modulation technology which is widely utilized in the switching mode power supply. The PWM signal is generated by digital signal processor to control the MOSFET driver directly. The MOSFET drive has replaced the analog components, including digital-to-analog converter, operational amplifier and power amplifier, required in the traditional analog servo driver. Improvement of the system can be seen in performance, stability, dimension, complexity, maintenance, free of adjustment and cost-reduction by using MOSFET driver in the digital servo driver.
Since the full digital controller does not send the control signal through the analog parts to the servo valve, the signal propagation delay has been reduced to be less than 100 nanoseconds. In summary, the full digital platform controller proposed by this research has a faster response and outstanding performance compared with all previous developed controllers.

並列關鍵字

Motion Cue ； Virtual Reality ； Stewart Platform ； Digital Controller ； Digital Driver ； Switching Mode Power Supply ； Pulse Width Modulation ； Digital Signal Processor ； MOSFET Driver ； Servo Driver

參考文獻

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