Planning coordinated motions for tethered planar mobile robots

TL;DR

This paper addresses the complex problem of planning coordinated motions for multiple tethered mobile robots, proposing algorithms for feasible motion planning in the most practical motion mode, validated through simulations and hardware tests.

Contribution

It introduces algorithms for planning and coordinating tethered robot motions in the Straight & Concurrent mode, a novel approach for non-intersecting cable configurations.

Findings

Algorithms effectively detect realizable cable configurations.

Validated motion plans in simulations and hardware.

Insights into motion modes for tethered robots.

Abstract

This paper considers the motion planning problem for multiple tethered planar mobile robots. Each robot is attached to a fixed base by a flexible cable. Since the robots share a common workspace, the interactions amongst the robots, cables, and obstacles pose significant difficulties for planning. Previous works have studied the problem of detecting whether a target cable configuration is intersecting (or entangled). Here, we are interested in the motion planning problem: how to plan and coordinate the robot motions to realize a given non-intersecting target cable configuration. We identify four possible modes of motion, depending on whether (i) the robots move in straight lines or following their cable lines; (ii) the robots move sequentially or concurrently. We present an in-depth analysis of Straight & Concurrent, which is the most practically-interesting mode of motion. In particular, we propose algorithms that (a) detect whether a given target cable configuration is realizable by a Straight & Concurrent motion, and (b) return a valid coordinated motion plan. The algorithms are analyzed in detail and validated in simulations and in a hardware experiment.