Stability and traction control of an actively actuated micro‐rover

Abstract

This article addresses the issue of enhancing mobility of actively actuated vehicles by the use of optimal force distribution, and by actively controlling the location of the center of mass of the vehicle body. Force distribution in actively actuated vehicles is an underspecified problem, and optimal force distribution leads to improved contact conditions. Actively actuated vehicles also possess the ability to vary their configuration. This capability can be used to locate the center of mass of the system to further enhance mobility by providing sufficient traction, and ensuring vehicle stability, during difficult vehicle maneuvers. In this work, the general idea of control of the location of the center of mass, followed by optimal force distribution, is addressed first. This is followed by an application of these ideas to Gofor, a simple actively actuated wheeled micro‐rover system, that has been designed and fabricated at the Jet Propulsion Laboratory. An algorithm to achieve desired traction and stability has been developed. Simulation studies were performed to investigate negotiation of a vertical surface. It was found that one set of wheels readily climbed the vertical surface with the use of active mass and force distribution. This is a significant improvement over traditional wheeled vehicle systems. © 1994 John Wiley & Sons, Inc.

Slope traversability analysis of reconfigurable planetary rovers

“…Another possible factor is errors in the parameters used for the simulations. As shown in Fig 12(d), simulation results underestimated slip ratio s, which therefore means that v x is overestimated (see (1)). Based on (2), overestimation of v x provides underestimation of slip angle β.…”

“…Such rovers are called "reconfigurable robots" [2], and several studies have proved their potential to negotiate challenging terrain. Studies on reconfigurable rovers have thus far primarily focused on an improvement of their traction or rollover stability on rough terrain [1]- [3]. On the other hand, Wettergreen et al [4] showed experimentally that a downhill sideslip can be reduced by tilting a rover along the uphill direction when the rover traverses sandy slopes.…”

Rover control based on an optimal torque distribution - Application to 6 motorized wheels passive rover

“…For wheeled rough terrain robots, enhanced performances can be obtained by maximizing the traction [2]. This allows getting the maximum from a rover in terms of obstacle climbing capability or minimizes its risk of getting stuck.…”

Development of a Terrain Adaptive Stability Prediction System for Mass Articulating Mobile Robots

“…For these systems researchers have proposed a number of approaches [3,7,8,9,11] that can be broadly classified as quasi-static stability approaches. In a quasi-static approach it is assumed that the vehicle motion relative to an inertial reference frame is slow (e.g., 1 m/s or less), therefore inertial accelerations can be neglected with the exception of gravitational acceleration.…”

“…As a result, the vehicle does not experience inertial forces that might trigger the tipover event. Approaches based on the support polygon are presented in [7,9,11]. These approaches suffer from the common problem of not measuring true cg motion while still assuming slow velocities.…”