OPTIMAL DESIGN AND CONTROL OF VARIABLE IMPEDANCE ACTUATED ROBOTS

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Date

2019

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Nazarbayev University School of Engineering and Digital Sciences

Abstract

In this thesis, the challenging problems of design and control of variable impedance actu ated robots are considered. The difficulties arise due to nonlinear dynamics, physical con straints of the system, and presence of additional actuators and nonlinear elastic/damping elements. As a result, we propose a control methodology, which takes into account system constraints and input bounds, guarantees system utilization to its full potential, and closely achieves the system’s target performance level. The thesis consists of seven chapters. The first chapter gives a broad introduction to the problem and provides the literature review. For example, differences between position-controlled robots and variable impedance actu ated robots are discussed, their corresponding advantages and disadvantages are presented and compared, past design and control solutions are reviewed, and the hypothesis is de scribed. The second chapter covers the proposed closed-loop control methodology for variable stiffness actuated robots. This chapter covers the general idea behind closed-loop control of variable impedance actuated robots using model predictive control, and it also includes simulations and experimental results. The augmentation of the variable stiffness robots with reaction wheels is described in chapter three. Specifically, the advantages of using reaction wheels to actuate the variable stiffness robots are discussed. This is fol lowed by a discussion of time-optimal control of variables stiffness robots in chapter four. This chapter presents and describes two time-optimal control problems: minimum time for target performance and minimum time for maximum performance. In chapter five energy optimal control of variable stiffness robots is described. In particular, three energy-optimal control problems are defined: maximum performance with limited energy, target perfor mance with minimum energy and maximum performance with minimum energy. Then chapter six contains successive linearization-based model predictive control of variable stiffness robots. The main idea of this chapter is that linearization might be beneficial for model predictive control of nonlinear systems due to a simpler model and the resulting smaller sampling time. Finally, chapter seven describes the potential impact of our research in the field of robotics and society.

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Type of access: Open

Citation

Zhakatayev, A. (2019). Optimal Design and Control of Variable Impedance Actuated Robots. Nazarbayev University School of Engineering and Digital Sciences

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