在傳統的阻抗控制器中，若選擇目標阻抗中的慣性矩陣使之與系統慣性矩陣相同，則可抵銷其中之力回授項，以達到免力回授的目的。但是，系統慣性矩陣是位置向量的函數，隨著機械臂的運動，其內部元素一直在變動；而目標阻抗中的慣性矩陣則是常數矩陣，因此這兩者不可能相等，也就無法完成力回授項的抵銷。傳統上，要免除力回授的麻煩，均要使用力估測器來估算接觸力。本文提出一無須力回授之機械臂阻抗控制器，其主要概念在修改目標阻抗中接觸力的係數矩陣，讓力回授項可以逕行抵銷。新控制器既不需要力感測器，也不使用力估測器，如此一來不僅節省了成本，也使得控制器設計容易許多，在工業上更利於使用與實現。新控制器在自由空間中的追跡性能，與傳統阻抗控制者相同；在受限空間中的軌跡，也與傳統者無異。其僅在接觸力與控制量上，與傳統阻抗控制器不同。但是，藉由選擇目標阻抗中的慣性矩陣，可以改變這兩者的大小，這在實際應用上，並不會造成困擾。另外，本文亦嘗試設計新控制器的適應控制版本，以容忍系統中的諸多不確定項，其結果可作為後續發展之參考。最後，本文以電腦模擬二軸剛性機械臂在平面受限空間的順應運動，來證明此方法的有效性，並與傳統阻抗控制做比較。

The traditional impedance controllers must use force sensors to feedback contact forces, making them costly to achieve, greatly affecting the willingness of industrial applications. Many scholars have proposed to replace force sensors with force estimators, but their complex mathematics results in difficulties in stability proof as well as in industrial implementation. Lee (2021) proposed to modify the coefficient matrix of the contact force term in the target impedance to enable force cancellation so that the force feedback can be avoided and hence there is no need to install a force sensor, nor a force estimator. An adaptive control version of the force cancellation impedance controller was also proposed in Lee (2021) to deal with the uncertain parameter problem. However, since the calculation of the reference model states relies on external force information, the force information is still inevitable. In this thesis, a new force cancellation adaptive impedance controller is proposed based on the function approximation technique to completely eliminates the need of force feedback. Rigorous mathematical justification in closed loop stability is given in detail and computer simulations are performed to verify the efficacy of the proposed design.

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李昆儒，無須力估測器之機械臂無力回授阻抗控制器設計，國立台灣科技大學機械工程研究所，碩士學位論文，2021。