Autonomous Mobile Robots in Unknown Outdoor Environments

Xiaorui Zhu, Youngshik Kim, Mark A. Minor, Chunxin Qiu

• Publisher: CRC Press
• Year: 2017
• Topic: Technology & Engineering
• eBook ISBN:
  9781351647533
• Subtopic: Information Technology
• Index: Technology & Engineering

Mobile robots have been increasingly applied in many different scenarios, such as space exploration and search and rescue, where the robots are required to travel over uneven terrain while outdoors. This book provides a new framework and the related algorithms for designing autonomous mobile robotic systems in such unknown outdoor environments.

III

MOTION CONTROL

Chapter 3

Cooperative Motion Control and Sensing Architecture

3.1 Introduction

The motion control of wheeled mobile robots has received appreciable attention where rigid, axle-wheeled mobile robots are predominant platforms. In earlier stages, most research was based on the kinematic model of a wheeled mobile robot where the input was velocity. However, tracking the velocity commands with an actual robot and rejecting the resulting drift was not trivial. Thus, the uniform dynamic controllers derived in [52,53] were based on the kinematic and dynamic model of the robot such that the robot can be controlled using wheel torque commands. As we mentioned in Chapter 2, a mobile robot working on the fields such as CFMMR is different from other types of mobile robots in mechanism, which correspondingly results in different motion-control issues. For instance, motion control of the CFMMR is different in two aspects. First, the physical constraints, especially the axle velocity and curvature constraints imposed by the frame, are not typical in rigid-body, wheeled mobile robots that are the focus of the uniform dynamic controllers. Second, the interaction forces between the axles are highly nonlinear functions of relative axle postures. Thus, coordinating relative axle postures is a critical concern that should not be considered by the uniform dynamic controllers. In contrast, the motion-control architecture discussed in this chapter is more suitable for coordinating motion of the axles in lieu of interaction constraints, which could frequently appear in field robotic systems.

Coordination is a common issue in cooperative mobile robotics, and has been studied with a variety of techniques [54–59]. Some of them only focus on motion planning and coordination issues without sensor architecture involved [54,58]. Some consider only motion planning and sensor architecture, ignoring robot dynamics [54,57]. Others focus only on dynamic motion control and coordinated force control without considering motion planning and sensor issues [55,56,59]. A number of cooperative wheeled mobile robots have been investigated in recent decades. The most well-known cooperative wheeled mobile robot was the snakelike robot Genbu, which used entirely passive joints to allow cooperation amongst wheel axles for adaptation to uneven terrain. However, motion control of Genbu focused only on simple posture alignment and functional ability [60]. No one considered general navigation issues and accurate motion control combining motion planning, dynamic motion control, and sensor fusion. There was no general solution to resolve all three aspects. In reality, motion planning, dynamic control, and sensor architecture issues, however, all affect the efficiency of cooperative motion control.

Burdick and his students proposed controllability and motion-planning issues for multi-model sy...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Contents
• Authors
• Section I Introduction
• Section II Mechanism
• Section III Motion Control
• Section IV Localization and Mapping
• References
• Index