Effects of terrain irregularities on wheeled mobile robot

Robotica ◽  
2003 ◽  
Vol 21 (2) ◽  
pp. 143-152 ◽  
Author(s):  
Maria Prado ◽  
Antonio Simón ◽  
Ana Pérez ◽  
Francisco Ezquerro
Keyword(s):  
Mobile Robot ◽  
Wheeled Mobile Robot ◽  
The Body ◽  
Uneven Terrain

The influence of ground irregularities on the behavior of a wheeled mobile robot (WMR) navigating on uneven surfaces is addressed. The paper studies the vibratory movements induced on the body of the WMR, in order to analyze its ability for carrying out on-board tasks, and on the accuracy of the data collected by its external sensorial systems. The adhesion capability of the wheels of the WMR on this uneven terrain is also studied, since it conditions the braking, traction and steering performance. The method is applied to the WMR RAM.

Kinematics of Wheeled Mobile Robots With Toroidal Wheels on Uneven Terrain

2003 ◽  
Author(s):  
Nilanjan Chakraborty ◽  
Ashitava Ghosal
Keyword(s):  
Mobile Robot ◽  
Thin Disk ◽  
Wheeled Mobile Robot ◽  
Variable Length ◽  
Ground Contact ◽  
Wheeled Mobile Robots ◽  
Holonomic Constraints ◽  
Uneven Terrain ◽  
Passive Joint ◽  
Simulation Results

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. Simulation results show that a three-wheeled WMR can negotiate uneven terrain without slipping. Our proposed approach presents an alternative to variable length axle approach.

Tip over Stability Analysis of a Three-Wheeled Mobile Robot Capable of Traversing Uneven Terrains without Slip

2011 ◽  
Vol 110-116 ◽  
pp. 2940-2947 ◽  
Author(s):  
Tharakeshwar Appala ◽  
Ashitava Ghosal
Keyword(s):  
Stability Analysis ◽  
Mobile Robot ◽  
Wheeled Mobile Robot ◽  
Free Motion ◽  
Lateral Tilt ◽  
Uneven Terrain ◽  
Stability Measure ◽  
Angle Stability ◽  
The Stability ◽  
Measure Technique

A mobile robot traversing an uneven terrain can undergo tip over instability when one or more wheels of the mobile robot losses contact with the uneven terrain. In this paper, we study the tip over stability of a three wheeled mobile robot. The three wheeled mobile robot studied in this paper has torus shaped rear wheels and have the ability of lateral tilting – a condition required for slip free motion on uneven terrain. The torus shaped wheels and slip free motion makes the dynamics and tip over stability analysis more difficult and interesting. In this paper, the force-angle stability measure technique is used to analyze and detect tip over instability. Simulation results of the stability analysis shows that the wheeled mobile robot with lateral tilt of rear wheels is capable of moving on certain kinds of rough terrains without tip over.

Dynamic Modeling and Simulation of a Wheeled Mobile Robot for Traversing Uneven Terrain Without Slip

2004 ◽  
Vol 127 (5) ◽  
pp. 901-909 ◽  
Author(s):  
Nilanjan Chakraborty ◽  
Ashitava Ghosal
Keyword(s):  
Mobile Robot ◽  
Model Simulation ◽  
Equations Of Motion ◽  
Nonholonomic Constraints ◽  
Wheeled Mobile Robot ◽  
Constant Length ◽  
Lateral Tilt ◽  
Uneven Terrain ◽  
Inverse Kinematics Problem ◽  
Slip Motion

It is known in literature that a wheeled mobile robot (WMR), with fixed length axle, will undergo slip when it negotiates an uneven terrain. However, motion without slip is desired in WMR’s, since slip at the wheel-ground contact may result in significant wastage of energy and may lead to a larger burden on sensor based navigation algorithms. To avoid slip, the use of a variable length axle (VLA) has been proposed in the literature and the kinematics of the vehicle has been solved depicting no-slip motion. However, the dynamic issues have not been addressed adequately and it is not clear if the VLA concept will work when gravity and inertial loads are taken into account. To achieve slip-free motion on uneven terrain, we have proposed a three-wheeled WMR architecture with torus shaped wheels, and the two rear wheels having lateral tilt capability. The direct and inverse kinematics problem of this WMR has been solved earlier and it was shown by simulation that such a WMR can travel on uneven terrain without slip. In this paper, we derive a set of 27 ordinary differential equations (ODE’s) which form the dynamic model of the three-wheeled WMR. The dynamic equations of motion have been derived symbolically using a Lagrangian approach and computer algebra. The holonomic and nonholonomic constraints of constant length and no-slip, respectively, are taken into account in the model. Simulation results clearly show that the three-wheeled WMR can achieve no-slip motion even when dynamic effects are taken into consideration.

scholarly journals Enhanced closed-loop systematic kinematics analysis of wheeled mobile robots

2019 ◽  
Vol 16 (4) ◽  
pp. 172988141986324
Author(s):  
Ziyong Han ◽  
Shihua Yuan ◽  
Xueyuan Li ◽  
Junjie Zhou
Keyword(s):  
Mobile Robot ◽  
Mobile Robots ◽  
Time Derivative ◽  
Wheeled Mobile Robot ◽  
Central Position ◽  
Wheeled Mobile Robots ◽  
Kinematic Chains ◽  
Uneven Terrain ◽  
The Matrix ◽  
Kinematic Modelling

The traditional homogeneous transform maintains central position in the kinematic modelling of robotics. However, for these kinematic modelling of wheeled mobile robots over uneven terrain, the homogeneous transform that represents angular velocity implicitly in the time derivative of the rotation matrix has a drawback in orientation representation. In this article, to improve the angular representation, a new general systematic method for kinematics modelling and analysis of wheeled mobile robot is proposed. The approach uses the Sheth–Uicker convention and loop-closure kinematic chains to derive the position, velocity and acceleration kinematics. The screw coordinates are used to reform the velocity kinematics to centroidal kinematics; then, the Jacobian calculation is simplified to solve the screw vector algebra equations instead of the matrix equations. Meanwhile, the linear and angular components of the centroidal kinematics are endowed with physical meanings and are easy to be selected as control variables. The approach is applied to a wheeled mobile robot, and its effectiveness is verified by the simulation results with various terrain.

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