Abstract
Based on two-dimensional (2-D) linear system theory, this thesis proposes a design method for a filter-based iterative learning control (FILC) scheme. The FILC scheme consists of a feedback controller and a feedforward filter. The 2-D model for the FILC is established in the form of the so-called “Roessor’s model”. Moreover, stability for a 2-D separable model can be simplified with one criterion to be met. In order to utilize the criterion derived from the 2-D separable system, the overall FILC control system is constructed in the form of a 2-D separable system by assuming a new state for the 2-D model. Therefore, convergence of the overall control system can be proved by stability of 2-D separable model and a condition for convergence of the overall control system can be reached. Moreover, to validate the design criterion of the FILC scheme in this thesis, we develop a pneumatic power active lower-limb orthosis (PPALO), and its dynamic model is also established to verify the performance of the proposed controller. Additionally, the wavelet transform filter (WTF) is adopted as the feedforward filter to extract the learnable part from the error signal which can be used to update the control profile. Thus, the effects from unlearnable dynamics on the controlled system can be attenuated by a PD feedback controller. Finally, using PPALO as the controlled plant, we conduct some trajectory tracking control simulations and experiments to validate the proposed scheme.