Design and Implementation of an
Omni-directional Robotic Ground
Vehicle
Andrew Niedert, Yazan Aljeroudi, Dr. Nassif Rayess, and Dr. Richard Hill
Department of Mechanical Engineering, University of Detroit Mercy
Purpose
The purpose of this project is to validate a novel robotic ground vehicle design that has high-speed
capability, omni-directional mobility and modest off-road capabilities. These goals will be achieved
through the construction of the mechanical platform for the vehicle, as well as through the
implementation of a control system that will assist a human driver in the teleoperation of the vehicle.
The
Vehicle
Overall Mechanical Design
Pod Design
 Active Offset Split Castor (ASOC) Design
 Fully Independent suspension
 Ability to maintain traction of all six wheels
 Each DC wheel motor is independently controlled
 Motor motion is measured by Hall-effect sensors
 Pod rotation is measure by optical encoders
Conventional wheels
Catia rendering of the designed vehicle
The vehicle in its current configuration
Assembled pod
Vehicle Chassis
 Each pod, and in turn the vehicle, is steered by differentially commanding the speed/torque of individual wheels
 Vehicle can strafe in any direction, rotate about its center, or drive like a conventional vehicle
 Can lead with two pods for stability or one pod for agility
 Slip rings allow for 360 degree pod motion while maintaining an electrical connection between the vehicle
batteries, computer and data acquisition devices and the individual wheel motors and controllers
Control
Software
Hinge joint
Split D
Offset S
Top View: Active Spit Castor (ASOC) Design
 Vehicle control software is implemented in the LabVIEW program from National
Instruments running on a laptop on-board the vehicle
 LabVIEW allows for data acquisition as well as user inputs and actuator commands
 Software can interpret wireless commands from a PDA or video game controller
 Open-loop control is currently achieved using an inverse kinematic vehicle model
 Closed-loop control of vehicle heading is currently being developed employing an
inertial measuring unit; a heuristic stability control algorithm is also to be developed
MicroStrain 3DM-G25
Inertial Sensing Device
Data Acquisition Card
Sends and receives signals from hardware
LabVIEW Front Panel
Vehicle Information GUI
LabVIEW Back Panel
Motor input commands and data acquisition
Wireless GamePad Control
Xbox 360 controller (top side controls)
Vehicle Characterization and Simulation
Simplified longitudinal vehicle simulation in SIMULINK
Vehicle characterization has been performed for the purposes of developing a dynamic simulation of the
vehicle and a more advanced closed-loop control strategy
 Dynamics of the motors and their controllers have been approximated as 1st and 2nd order models
 Vehicle and component inertias have been identified using a scale and multi-filar suspension setup
 A simple longitudinal simulation of the vehicle has been implemented in Simulink
 The characterization of the wheel/road interaction is being empirically determined
A multi-body model of the vehicle will be interfaced with the current simulation in order to simulate lateral
motion; this model will be implemented using the SimMechanics toolbox or using WorkingModel 2D
This simulation will be used to develop a closed-loop control strategy and to test different vehicle architectures
Ground Robotics Reliability Center
Motor controller
(Accepts signals sent by the DAQ assistant)
Acknowledgments
This work was funded in part by:
The University of Detroit Mercy
Faculty Grant Incentive Program,
and