Kinematics Of Wheeled Mobile Robots Research Articles

Unified Tracking and Regulation Visual Servo Control for Wheeled Mobile Robots

AbstractThe problem of unified tracking and regulation visual servo control is addressed in this paper, for a wheeled mobile robot (WMR) equipped with a single monocular camera system. The desired trajectory or desired fixed position and orientation are defined using a prerecorded image sequence (i.e., a video) or a single image (i.e., a snapshot) of four feature points. Euclidean homographies are developed by exploiting the projective geometric relationships that exist between the feature points in the live image and the prerecorded sequence of images and the corresponding feature points in a fixed reference image. The information obtained from the Euclidean homographies is then utilized to recast the WMR kinematics in a standard WMR form. A rigorous Lyapunov‐based analysis is provided to show that the proposed visual servo control approach achieves simultaneous tracking and regulation control for the on‐board camera‐in‐hand problem.

The Kinematics of Wheeled Mobile Robots With Dual-Wheel Transmission Units

The dual-wheel transmission unit, an innovative driving mechanism for wheeled mobile robots, was introduced elsewhere. In this paper, we discuss wheeled mobile robots with such units, supplied with a novel suspension to keep the wheel-ground contact in spite of the irregularities of the floor. We derive closed-form solutions and constraints pertaining to the direct and inverse-kinematics problems of these robots; the constraints reveal the mobility of the robots at hand. Furthermore, we provide an algorithm for the trajectory tracking of the same robots that relies on a novel technique, which is termed the companion-curve method.

Kinematics of wheeled mobile robots on uneven terrain

This paper deals with the kinematic analysis of a wheeled mobile robot (WMR) moving on uneven terrain. It is known in literature that a wheeled mobile robot, with a fixed length axle and wheels modeled as thin disk, will undergo slip when it negotiates an uneven terrain. To overcome slip, variable length axle (VLA) has been proposed in literature. In this paper, we model the wheels as a torus and propose the use of a passive joint allowing a lateral degree of freedom. Furthermore, we model the mobile robot, instantaneously, as a hybrid-parallel mechanism with the wheel–ground contact described by differential equations which take into account the geometry of the wheel, the ground and the non-holonomic constraints of no slip. We present an algorithm to solve the direct and inverse kinematics problem of the hybrid-parallel mechanism involving numerical solution of a system of differential-algebraic equations. Simulation results show that the three-wheeled WMR with torus shaped wheels and passive joints can negotiate uneven terrain without slipping. Our proposed approach presents an alternative to variable length axle approach.

THE KINEMATICS Of MOBILE ROBOTS WITH ORIENTABLE SINGLE AND DUAL WHEELS ROLLING ON A PLANE

The kinematics of wheeled mobile robots (WMRs) equipped with an arbitrary number of either conventional orientable wheels or dual-wheel units (DWUs) is the subject of this paper. The configuration of a robot with s such, wheels is defined by 3 + 2s variables, three for the platform configuration and two for each single wheel or dual-wheel unit. However, not all variables related to the wheel configuration are independent since, for the platform to be able to undergo an arbitrary planar motion, the wheel-unit configurations must satisfy s − 2 compatibility conditions. Therefore, the number of independent variables which defines the degree of freedom (dof) of the system is 3 + 2s − (s − 2) = s + 5. On the other hand, it is made apparent that wheeled mobile robots equipped with at least three orientable wheels have three independent generalized velocities. Hence, the mobility of these robots, which is defined as their number of independent generalized velocities, is three; in other words, they are of full mobility.

A generic kinematic formulation for wheeled mobile robots

This article presents a generic kinematic formulation and a procedure developed to deduce the kinematics of wheeled mobile robots (WMRs), also known in the literature as driverless ground vehicles, automated guided vehicles (AGVs), and autonomous transit vehicles (ATVs). The generic formulation to deduce the kinematics of WMRs with various combinations of driving and steering wheels is obtained by making use of the transformation approach and modifying the kinematic formulations developed for WMRs with inclined steering columns. A general expression for the angular velocity of wheel slip is derived to extend the suitability of the formulations for WMRs with various combinations of driving and steering wheels. It is illustrated that the procedure developed provides the final form of the kinematic equations by providing only the kinematic parameters of the WMR, including the type of wheels employed for the generic model. This approach is useful to automate the modeling procedure to obtain either symbolic expressions or numerical values for WMR kinematics. Several case studies are presented to illustrate the simplicity of the developed approach. © 1997 John Wiley & Sons, Inc.

On the Kinematics of Wheeled Mobile Robots

A wheeled mobile robot is here modelled as a planar rigid body that rides on an arbitrary number of wheels. The rela tionship between the rigid body motion of the robot and the steering and drive rates of wheels is developed. In particular, conditions are obtained that guarantee that rolling without skidding or sliding can occur. Explicit differential equations are derived to describe the rigid body motions that arise in such ideal rolling trajectories. The simplest wheel configura tion that permits access of arbitrary rigid-body motions is determined. Then the question of slippage due to misalign ment of the wheels is investigated by minimization of a non- smooth convex dissipation functional that is derived from Coulomb's Law offriction. It is shown that this minimization principle is equivalent to the construction of quasi-static motions. Examples are presented to illustrate the models.