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

Abstract

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.

Maneuvering control of planar snake robots based on a simplified model

“…A similar idea for the body shape control is previously presented in [20], however, in contrast, here we use a more complex dynamic compensator for λ which enables us to control the position of the robot along the desired path in addition to the forward velocity of the robot, and thus to solve the maneuvering control problem.…”

“…The major contribution of the orientation controller w.r.t. [20] is that here we stabilize the orientation of the robot to a time-varying reference which allows convergence of the robot to a desired path rather than a constant angle as in [20].…”

“…In this paper we show that it is possible to combine the path following control approach of [10] and the velocity control approach in [20] in order to solve the maneuvering control problem. To this end, we replace the reference signal of [20] with a path following guidance law, which enables the robot to follow a time-varying reference angle, in contrast with the constant reference angle in [20].…”

“…To this end, we replace the reference signal of [20] with a path following guidance law, which enables the robot to follow a time-varying reference angle, in contrast with the constant reference angle in [20]. Furthermore, we develop a new dynamic compensator which controls the position of the robot along the path in addition to its velocity as in [20]. Using this dynamic compensator also enables us to relax a restricting assumption on the forward velocity of the robot in the path following control approach given in [10].…”

Formation control of underactuated bio-inspired snake robots

“…In [17], a direction following controller is proposed, which regulates the orientation and the forward velocity of the robot to constant references. A similar approach is used in [18][19], where the design is based on the simplified dynamic model for the snake robot which resolves the singularity in the control law derived in [17]. In [20], a maneuvering controller for the snake robot is derived using singular perturbation theory.…”