Control Strategy for a SnakeLike Robot Based on Constraint Force and Verification by Experiment

Advanced Robotics (Impact Factor: 0.57). 05/2009; 23(7):907-937. DOI: 10.1163/156855309X443115
Source: DBLP


This paper describes a locomotion method of a snake-like robot with passive wheels based on a stabilizing control theory for nonlinear systems. The advantage of this method is that the locomotion can be realized only by a state feedback control law, while many reported methods require some reference trajectory such as the serpenoid curve or are realized not only by a locomotion control, but also by a posture control to avoid singular postures. The proposed method evaluates the friction force of passive wheels in the quadratic-like cost function, so that the efficiency with respect to the input can be improved. The state-dependent Riccati equation technique is utilized to realize this method and it permits us to tune the system performance like an optimal control case. The projection method, one of the nice modeling techniques, is utilized to derive both the plant and the friction model. The effectiveness of the proposed method is verified through numerical simulations and experiments.

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    ABSTRACT: The control of a snake-like robot is a challenging problem because of the complex dynamics and the unknown environment. We have proposed an energy-based method, called passive creeping, to control the serpentine locomotion. This paper lays emphasis on the stability and the adaptability of the method. First, the local orbital stability of the movement is explicated based on the maximal Lyapunov exponent and the recurrence plot. Second, the adaptability to the environment is analyzed, and an optimal adaptive law based on the energy proportion is put into use to perfect the method. The particular advantages of the passive creeping include the comprehensive concept, the explicit control, and the inherent adaptability.
    Intelligent Robots and Systems (IROS), 2010 IEEE/RSJ International Conference on; 01/2010
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    ABSTRACT: The control of a snake-like robot is a challenging problem because of the complex dynamics. In this paper, we present a novel method, called passive creeping, to control the serpentine locomotion of the snake-like robot. The kernel of this method is composed of the following two concepts: 1) dynamic shift brings the tendency toward the serpentine locomotion; and 2) energy links the environments and the dynamics with the control law based on passivity. The head module leads the movement, and the body modules push the robot forward. The movement is a dynamic process from an unordered state to an ordered state, and the maximal Lyapunov exponent explicates the orbital stability of the movement in the phase space. Especially, the snake-like robot can adapt to the environments with different friction coefficients according to the dynamic state not the environment information. The validity and adaptability of the method is studied through simulations.
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    ABSTRACT: locomotion. In the paper, we present a hypothesis that the energy state of the robot can influence the locomotor adaptation. And then we lay emphasis on experiments in order to test the hypothesis and validate the passive creeping. A locomotion experiment and a drag experiment demonstrate the adaptability of the passive creeping to variable environments and different dynamics (or payloads), respectively. In the experiments, an optical motion capture system is used to obtain the kinetic energy information of the snake-like robot in real time.
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