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A System of Intelligent Robots–Trained Animals–Humans in a Humanitarian Demining Application
Published in Thrishantha Nanayakkara, Ferat Sahin, Mo Jamshidi, Intelligent Control Systems with an Introduction to System of Systems Engineering, 2018
Thrishantha Nanayakkara, Ferat Sahin, Mo Jamshidi
Exploitation of passive dynamics. Most tropical minefields have been abandoned lands for decades. Due to a long period of soft deposits and growth of weeds and grasses, the robot has to walk on a soft terrain. Usually, soft terrains are springy and readily deformable. Therefore, the robot should be designed to make the best use of the passive dynamics of locomotion on soft terrain conditions. Out of many possible locomotion technologies, such as traction, wheels, legs, gliding, slithering, etc., one has to decide the best method to suit the typical environments.
On robustness against disturbances of passive systems with multiple invariant sets
Published in International Journal of Control, 2021
N. F. Barroso, R. Ushirobira, D. Efimov, A. L. Fradkov
Another popular way of studying the influence of exogenous inputs and the stability of interconnections is based on the concept of passivity. The class of passive dynamics is omnipresent in mechanics, electric circuits and systems biology (Fradkov, 2007; Nijmeijer & van der Schaft, 1990; Ortega et al., 1998). Unfortunately, the passivity of systems does not imply directly its robustness against perturbations; it is mainly a kind of nonlinear input–output relation. Consequently, the conditions of ISS and iISS of passive systems with respect to a compact and connected invariant set were treated before in the literature: Arcak and Kokotović (2001) and Efimov (2006), Efimov and Fradkov (2008) where the ISS/iISS stabilisability by an output feedback for passive and strictly passive systems was considered.
Periodic motion planning and control for underactuated mechanical systems
Published in International Journal of Control, 2018
Zeguo Wang, Leonid B. Freidovich, Honghua Zhang
A systematic periodic motion planning and periodic motion control design method is proposed in this paper. It could be applied to underactuated mechanical systems with arbitrary underactuation degree. The idea originates from the fact that any continuous periodic function could be decomposed into an infinite uniformly converging Fourier series and, therefore, it can be arbitrarily accurately approximated by a trigonometric polynomial. Hence, the reference trajectory of each state of the system is assumed to be a truncated Fourier series. Moreover, this reference trajectory should satisfy differential constraints imposed by passive dynamics equations. Therefore, a numerical optimisation search is implemented to find the parameters to minimise the error, which is given by passive dynamics equations. An almost feasible periodic motion is defined in this way. The obtained reference trajectory does not satisfy the equations precisely but a feedback controller can be used to force the closed-loop system's feasible trajectories into a small neighbourhood of the desired approximately feasible motion.