Path following control of planar snake robots using a cascaded approach

Liljebäck, Pål; Haugstuen, Idar U.; Pettersen, Kristin Y.

doi:10.1109/cdc.2010.5717823

Cited by 31 publications

(72 citation statements)

References 35 publications

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“…No previous snake robot controller can command a snake robot to follow an arbitrary path, owing to the need for a sophisticated dynamic model and difficult-to-tune motion controller (24). With the two-wave mixing framework, however, steering a snake robot is simplified to adjusting only a few wave parameters, and the straightforward correspondence between the parameter value and the resultant behaviors allows intuitive high-level motion control of the robot.…”

Section: Significancementioning

confidence: 99%

Modulation of orthogonal body waves enables high maneuverability in sidewinding locomotion

Astley

Gong

Dai

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

110

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Many organisms move using traveling waves of body undulation, and most work has focused on single-plane undulations in fluids. Less attention has been paid to multiplane undulations, which are particularly important in terrestrial environments where vertical undulations can regulate substrate contact. A seemingly complex mode of snake locomotion, sidewinding, can be described by the superposition of two waves: horizontal and vertical body waves with a phase difference of ±90°. We demonstrate that the high maneuverability displayed by sidewinder rattlesnakes (Crotalus cerastes) emerges from the animal's ability to independently modulate these waves. Sidewinder rattlesnakes used two distinct turning methods, which we term differential turning (26°change in orientation per wave cycle) and reversal turning (89°). Observations of the snakes suggested that during differential turning the animals imposed an amplitude modulation in the horizontal wave whereas in reversal turning they shifted the phase of the vertical wave by 180°. We tested these mechanisms using a multimodule snake robot as a physical model, successfully generating differential and reversal turning with performance comparable to that of the organisms. Further manipulations of the two-wave system revealed a third turning mode, frequency turning, not observed in biological snakes, which produced large (127°) in-place turns. The two-wave system thus functions as a template (a targeted motor pattern) that enables complex behaviors in a high-degree-offreedom system to emerge from relatively simple modulations to a basic pattern. Our study reveals the utility of templates in understanding the control of biological movement as well as in developing control schemes for limbless robots.sidewinder | biomechanics | robotics | template | control P ropagating waves of flexion along the axis of a long, slender body (henceforth "axial waves") to produce propulsion is common in biological locomotion in aquatic and terrestrial environments. The majority of biological studies of axial wave propulsion at different scales have occurred in aquatic environments (1, 2). Understanding the efficacy of given wave patternswhich are often assumed to act in a single plane (e.g., mediolateral axial bending)-can be gained through full solution of the equations of hydrodynamics (3) or approximations (4). Terrestrial environments such as sand, mud, and cluttered heterogeneous substrates encountered by limbless axial undulators such as snakes can display similar (if not greater) complexity, yet far less attention has been paid to such locomotion (5, 6).Snake axial propulsion in terrestrial environments differs from fluid locomotion in two key ways. First, most substrates are not yet described at the level of fluids (7), making it a challenge to understand how substrate-body interactions affect locomotor performance, and therefore requiring robotic physical models. Second, the body may be both laterally and/or dorsoventrally flexed (5) to allow different elements of the body to contact ...

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Section: Significancementioning

confidence: 99%

Modulation of orthogonal body waves enables high maneuverability in sidewinding locomotion

Astley

Gong

Dai

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

110

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“…Furthermore, we derive the orientation error dynamics of the robot evaluated on the constraint manifold. This can be done by writing (11,15) in the error coordinates (φ 1 , . .…”

Section: B Enforcing the Vhc For The Shape Variables Of The Robotmentioning

confidence: 99%

“…The simplified dynamic model (10)(11)(12)(13)(14)(15)(16)(17) is suitable for the model-based direction following control design which will be presented in the following sections.…”

Section: Simplified Kinematic and Dynamic Equationsmentioning

confidence: 99%

“…Methods based on numerical optimal control are considered in [9] for determining optimal gaits during positional control of wheel-less snake robots. In [10,11], cascaded systems theory is employed to achieve path following control of a wheel-less snake robot described by a simplified model. In [12], a dynamic feedback control law is used to control the orientation of the robot to a reference angle defined by a path following guidance law.…”

Section: Introductionmentioning

confidence: 99%

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Virtual holonomic constraint based direction following control of planar snake robots described by a simplified model

Rezapour

Hofmann

Pettersen

et al. 2014

2014 IEEE Conference on Control Applications (CCA)

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Abstract-This paper considers direction following control of planar snake robots for which the equations of motion are described based on a simplified model. In particular, we aim to regulate the orientation and the forward velocity of the robot to a constant vector, while guaranteeing the boundedness of the states of the controlled system. To this end, we first stabilize a constraint manifold for the fully-actuated body shape variables of the robot. The definition of the constraint manifold is inspired by the well-known reference joint angle trajectories which induce lateral undulatory motion for snake robots. Subsequently, we reduce the dynamics of the system to the invariant constraint manifold. Furthermore, we design two dynamic compensators which control the orientation and velocity of the robot on this manifold. Using numerical analysis and a formal stability proof, we show that the solutions of the dynamic compensators remain bounded. Numerical simulations are presented to validate the theoretical design.

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“…Methods based on numerical optimal control are considered in [7] for determining optimal gaits during positional control of snake robots. In [8,9] cascaded systems theory is employed to achieve path following control of a snake robot described by a simplified model. Sliding mode control of the joint angles of a snake robot is considered in [10].…”

Section: Introductionmentioning

confidence: 99%

Differential geometric modelling and robust path following control of snake robots using sliding mode techniques

Rezapour

Pettersen

Liljebäck

et al. 2014

2014 IEEE International Conference on Robotics and Automation (ICRA)

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Abstract-This paper considers straight line path following control of wheel-less planar snake robots using sliding mode techniques. We first derive the Poincaré representation of the equations of motion of the robot using the techniques of differential geometry. Furthermore, we use partial feedback linearization to linearize the directly actuated part of the system dynamics. Subsequently, we propose an analytical solution to the robust path following control problem in two steps. In the first step, we use sliding mode techniques to design a robust tracking controller for the joints of the robot to track a desired gait pattern. In the second step, we stabilize an appropriately defined sliding manifold for the underactuated configuration variables of the robot, thereby guaranteeing convergence of the robot to the desired straight path. The paper presents simulation results which validate the theoretical results.

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Path following control of planar snake robots using a cascaded approach

Cited by 31 publications

References 35 publications

Modulation of orthogonal body waves enables high maneuverability in sidewinding locomotion

Modulation of orthogonal body waves enables high maneuverability in sidewinding locomotion

Virtual holonomic constraint based direction following control of planar snake robots described by a simplified model

Differential geometric modelling and robust path following control of snake robots using sliding mode techniques

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