Modeling, Design and Control of Multiple Low-Cost Robotic Ground Vehicles

Toward the ambitious long-term goal of a fleet of cooperating Flexible Autonomous Machines operating in an uncertain Environment (FAME), this thesis addresses several critical modeling, design and control objectives for ground vehicles. One central objective was to show how off-the-shelf (low-cost) remote-control (RC) “toy” vehicles can be converted into intelligent multi-capability robotic-platforms for conducting FAME research. This is shown for two vehicle classes: (1) six differential-drive (DD) RC vehicles called Thunder Tumbler (DDT ) and (2) one rear-wheel drive (RWD) RC car called Ford F-150 (1:14 scale). Each DDT -vehicle was augmented to provide a substantive suite of capabilities as summarized below (It should be noted, however, that only oneDDT -vehicle was augmented with an inertial measurement unit (IMU) and 2.4 GHz RC capability): (1) magnetic wheel-encoders/IMU for (dead-reckoning-based) inner-loop speed-control and outer-loop position-directionalcontrol, (2) Arduino Uno microcontroller-board for encoder-based inner-loop speedcontrol and encoder-IMU-ultrasound-based outer-loop cruise-positiondirectionalseparation-control, (3) Arduino motor-shield for inner-loop motor-speed-control, (4) Raspberry Pi II computer-board for demanding outer-loop vision-based cruiseposition -directional-control, (5) Raspberry Pi 5MP camera for outer-loop cruise-positiondirectional control (exploiting WiFi to send video back to laptop), (6) forwardpointing ultrasonic distance/rangefinder sensor for outer-loop separation-control, and (7) 2.4 GHz spread-spectrum RC capability to replace original 27/49 MHz RC. Each “enhanced”/ augmented DDT -vehicle costs less than $175 but offers the capability of commercially available vehicles costing over $500. Both the Arduino and Raspberry are low-cost, well-supported (software wise) and easy-to-use. For the vehicle classes considered (i.e. DD, RWD), both kinematic and dynamical (planar xy) models are examined. Suitable nonlinear/linear-models are used to develop inner/outer-loop