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Wheel-terrain contact angle estimation for planetary Exploration rovers

Vijayan, Ria (2018) Wheel-terrain contact angle estimation for planetary Exploration rovers. Master's, Lulea University of Technology.

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During space missions, real time tele-operation of a rover is not practical because of significant signal latencies associated with inter planetary distances, making some degree of autonomy in rover control desirable. One of the challenges to achieving autonomy is the determination of terrain traversability. As part of this field, the determination of motion state of a rover on rough terrain via the estimation of wheel-terrain contact angles is proposed. This thesis investigates the feasibility of estimating the contact angles from the kinematics of the rover system and measurements from the onboard inertial measurement unit (IMU), joint angle sensors and wheel encoders. This approach does not rely on any knowledge of the terrain geometry or terrain mechanical properties. An existing framework of rover velocity and wheel slip estimation for flat terrain has been extended to additionally estimate the wheel-terrain contact angle along with a side slip angle for each individual wheel, for rough terrain drive. A random walk and a damped model are used to describe the evolution of the contact angle and side slip angle over an unknown terrain. A standard strapdown algorithm for the estimation of attitude and velocity from IMU measurements, is modified to incorporate the 3D kinematics of the rover in the implementation of a nonlinear Kalman filter to estimate the motion states. The estimation results from the filter are verified using tests performed on the ExoMars BB2. The obtained contact angle estimates are found to be consistent with the reference values.

Item URL in elib:https://elib.dlr.de/121833/
Document Type:Thesis (Master's)
Title:Wheel-terrain contact angle estimation for planetary Exploration rovers
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Vijayan, Riaria.vijayan (at) dlr.deUNSPECIFIED
Date:August 2018
Refereed publication:No
Open Access:Yes
Gold Open Access:No
In ISI Web of Science:No
Keywords:Contact Angle; Side Slip Angle; Nonlinear Kalman Filter; Differential Kinematics; ExoMars BB2; Planetary Exploration Rovers
Institution:Lulea University of Technology
Department:Division of Space Technology
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Space Technology
DLR - Research area:Raumfahrt
DLR - Program:R SY - Technik für Raumfahrtsysteme
DLR - Research theme (Project):R - Project Morex
Location: Oberpfaffenhofen
Institutes and Institutions:Institute of System Dynamics and Control > Space System Dynamics
Deposited By: Barthelmes, Stefan
Deposited On:11 Oct 2018 11:38
Last Modified:31 Jul 2019 20:19

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