TEGOTAE-Based Control Scheme for Snake-Like Robots That Enables Scaffold-Based Locomotion
Snakes exhibit “scaffold-based locomotion” wherein they actively utilize terrain irregularities and move effectively by pushing their body against the scaffolds that they encounter. Implementing the underlying mechanism in snake-like robots will enable th
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Abstract. Snakes exhibit “scaffold-based locomotion” wherein they actively utilize terrain irregularities and move effectively by pushing their body against the scaffolds that they encounter. Implementing the underlying mechanism in snake-like robots will enable them to work well in unstructured real-world environments. In this study, we proposed a decentralized control scheme for snake-like robots based on TEGOTAE, a Japanese concept describing how well a perceived reaction matches an expectation, to reproduce scaffold-based locomotion. A preliminary experimental result showed that reaction forces from environment are evaluated based on TEGOTAE in real time and those beneficial for propulsion of the body are selectively exploited.
Keywords: Snake-like robot based locomotion
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TEGOTAE-based control
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Scaffold-
Introduction
Snakes actively utilize terrain irregularities and move effectively by pushing their body against the scaffolds that they encounter [1,3]. This behavior, which we call “scaffold-based locomotion,” is achieved by appropriately coordinating large number of bodily degrees of freedom in a decentralized manner. Clarifying the underlying mechanism will help develop robots that can work well in unstructured realworld environments. Unfortunately, however, previous models for the scaffoldbased locomotion could not reproduce the innate behavior of snakes [2–4]. To address this issue, here we propose a decentralized control scheme for scaffold-based locomotion from the viewpoint of TEGOTAE, a Japanese concept describing how well a perceived reaction matches an expectation. In this control mechanism, reaction forces from environment are evaluated based on TEGOTAE in real time and those beneficial for propulsion of the body are selectively exploited. The validity of the proposed control scheme is investigated via a preliminary experiment using a snake-like robot developed (Fig. 2). c Springer International Publishing Switzerland 2016 N.F. Lepora et al. (Eds.): Living Machines 2016, LNAI 9793, pp. 454–458, 2016. DOI: 10.1007/978-3-319-42417-0 46
TEGOTAE-Based Control Scheme for Snake-Like Robots
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Fig. 1. Scaffold-based locomotion of real snake (Elaphe climacophora).
Fig. 2. Schematic of the proposed model.
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Model
The schematic of the proposed model is shown in Fig. 1. Several segments are concatenated one-dimensionally via joints. Frictional anisotropy is implemented in each segment like real snakes, and the friction coefficient along the tangential direction is smaller than that along the normal direction. Each joint is controlled according to proportional control, and the target and real angle of the ith joint is denoted by φ¯i and φi , respectively. We assume that each segment can detect forces from the environment, and the contact forces detected at the ith segment from the right- and left-hand side are denoted by fr,i and fl,i , respectively.
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The target joint angle φ¯i is updated each time step as follows:
i+nf
φ¯1 (t + 1) = hd (t) + σ
τj (t)(fl,j (t) + fr,j (t)),
(1)
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