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標題: | 球型連桿手術機器人機構之開發與靜平衡設計 Development of a Spherical Linkage Surgical Robot and its Static Balance Design |
作者: | Chi-Hsiang Chen 陳麒翔 |
指導教授: | 蘇偉儁(Wei-Jiun Su) |
關鍵字: | 球形連桿,手術機器人,靜平衡,彈簧, spherical links,surgical robot,static balancing,spring, |
出版年 : | 2020 |
學位: | 碩士 |
摘要: | 對手術而言機器人的定位精度是非常重要的,而組裝誤差與控制精度將會影響手術器具的定位精度。因此為了盡量減少組裝誤差,採用球形連桿作為MIS機器人之結構零件。雖然串、並聯設計均能達到此功能需求,但串聯具有較大的到浮動慣性,而會造成馬達負載提升和控制的問題。在目前相關文獻裡,卻少有並聯型與串聯型機構的探討比較,得依據不同機型的特性來評估。 為了比較兩者的差異,本文以輸入扭力為評估標準。由於馬達扭力變化將會影響控制精度,而極值的大小將會決定減速機的背隙大小。因此透過Euler-Lagrange equation建立馬達扭力數學模型,並以simulink的模擬結果驗證其精確性。另外,由於兩機構的質量慣性不同,產生的振動對手術穩定也有所差異。模擬結果顯示,並聯型節省約40%的扭力,因此有利於馬達選用和控制器設計。除此之外,研究中以比較串聯型與並聯型在等速圓周運動下的搖撼力,結果表示並聯型相較串聯型的搖撼力較小,並聯型較適合做為MIS機器人基礎機構。 在決定以並聯機構為MIS機器人機構後。為了進一步減低馬達扭力負載,於是採用靜平衡設計來減低重力的影響。靜平衡以彈簧和配重為主要設計方法。為了瞭解何者較能有效減低扭力負載,後續將以兩方法在並聯機構上進行設計、比較。在彈簧法設計,本文改良了先前滑動對平衡設計的問題。在不增加先前方法的桿件數量下,成功設計出彈簧靜平衡機構,並討論彈簧各接點位置對位能的影響。最後以三根彈簧完成五連桿與伸縮機構之平衡。在配重設計,則以兩個配重塊達成靜平衡設計。但配重質量將會影響馬達動態負載,所以配重設計將以最佳化結果作為後續討論的模型。將配重最佳化後,彈簧設計和配重設計在扭力上的表現十分接近。此結果說明彈簧法不需最佳化即能與配重法最佳化相當,若將配重質量與原機構相當時,兩方法的扭力差異可達到1.6倍。因此彈簧法對於MIS機器人的控制輔助會是較佳設計。 For surgery, the positioning accuracy of the robot is very important, and the assembly error and control accuracy will affect the positioning accuracy of the surgical instrument. Therefore, in order to minimize the assembly error, the spherical linkages are used as the structural part of the MIS robot. Although both series and parallel mechanisms can achieve this functional requirement, the floating inertia of the series mechanisms will increase the motor load and complicate the control system design. However, there is little comparison between the parallel and series mechanisms in the literature. In order to compare the difference between the two, the input torque is used as the evaluation standard. Since the torque of the motor will affect the control accuracy, the mathematical model of the motor torque is established through the Euler-Lagrange equation, and the simulation results of simulink are used to verify to prove the mathematical model. In addition, due to the different mass inertias of the two mechanisms, the vibrations may cause different effects for surgical stability. The shaking force of the series and parallel mechanisms in a circular motion with constant speed is examined. The simulation results show that the parallel type saves about 40% of the torque, which benefits motor selection and controller design. Moreover, its shaking force of the parallel type is smaller than that of the series type, so it is more suitable as the basic mechanism of MIS robot. After deciding to use the parallel mechanism as the MIS robot mechanism, in order to further reduce the motor load, the static balance design was used to reduce the influence of gravity. The static balance is mainly designed with springs and counterweights methods. In order to understand which is more effective in reducing the torque load, two methods will be used to design and compare the parallel mechanism. In the spring method design, this paper improves the problem of the previous prismatic pair balance design. Without increasing the number of rods in the previous method, the statically balanced mechanism is successfully designed, and the influence of the position of each contact of the spring on the potential energy is discussed. Finally, three springs were used to complete the whole balance. In the counterweight design, two counterweights are used to achieve the static balance design. However, the weight of the counterweight will affect the dynamic load of the motor, so the counterweight design will be further optimized. After optimizing the counterweight, the torque distribution of the spring type and counterweight type are very close. This result shows that the spring method can achieve similar performance as the counterweight method without optimization. If the weight of the counterweight is equal to that of the original mechanism, the difference in torque between the two methods can reach 1.6 times. In conclusion, the spring method would be a better design for the MIS robots. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/67705 |
DOI: | 10.6342/NTU202003493 |
全文授權: | 有償授權 |
顯示於系所單位: | 機械工程學系 |
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