Integrated Planning and Control for Convex-bodied Nonholonomic systems using Local Feedback Control Policies

Abstract

We present a method for defining a hybrid control system capable of simultaneously addressing the global navigation and control problem for a convex-bodied wheeled mobile robot navigating amongst obstacles. The method uses parameterized continuous local feedback control policies that ensure safe operation over local regions of the free configuration space; each local policy is designed to respect nonholonomic constraints, bounds on velocities (inputs), and obstacles in the environment. The hybrid control system makes use of a collection of these local control policies in concert with discrete planning tools in order to plan, and replan in the face of changing conditions, while preserving the safety and convergence guarantees of the underlying control policies. This work is validated in simulation and experiment with a convex-bodied wheeled mobile robot. The approach is one of the first that combines formal planning with continuous feedback control guarantees for systems subject to nonholonomic constraints, input bounds, and non-trivial body shape.

Integrated motion planning and control for graceful balancing mobile robots

“…The contributions of this paper are as follows: (i) the notion of gracefully prepares relationship as a restrictive definition on the prepares relationship (Burridge et al 1999;Conner et al 2006), which ensures graceful switching between motion policies (see Sec. IV-C); (ii) an offline procedure to design a palette of motion policies, wherein the motion policies produce collision-free graceful motions in small domains of position space, and also gracefully prepare each other (see Sec.…”

“…Sequential composition was successfully applied to a variety of systems (Kantor and Rizzi 2003;Klavins and Koditschek 2000;Rizzi et al 2001). Conner et al presented an integrated motion planning and control procedure based on sequential composition to achieve navigation tasks for kinematic wheeled robots (Conner et al 2006). A map of the environment was randomly filled with instantiations of a pre-defined set of control policies using a partially automated procedure.…”

“…Each node in Ω(L) represents a valid instantiated motion policy Φ i ∈ L, and each directed edge from Φ i to Φ j represents the gracefully prepares relationship, i.e., Φ i G Φ j . The gracefully prepares graph is similar to the prepares graph presented in (Conner et al 2006), but differs from the fact that the edges represent the gracefully prepares relationship and not just the prepares relationship as explained in Sec. IV-C.…”

Integrated planning and control for graceful navigation of shape-accelerated underactuated balancing mobile robots

“…It was successfully applied to a variety of systems [7], [8]. Conner et al [9] used sequential composition to achieve global navigation tasks for convex-bodied wheeled mobile robots. The control policies were deployed on a map of the environment and their composability relationship was given by a directed graph called prepares graph.…”

“…III); (ii) an automatic instantiation procedure that generates a motion policy library from a small collection of motion policies (see Sec. IV-A); (iii) the notion of gracefully prepares relationship, which is a restrictive definition on the prepares relationship [6], [9] (see Sec. III-C); and (iv) the successful experimental testing on the ballbot platform to perform two navigation tasks, namely, point-point and surveillance motions along with handling disturbances (see Sec.…”