This work investigates the steering and wheel speed control of a completely custom built 8x8 scaled electric combat vehicle (SECV) which has been constructed to meet the Ackermann condition at low speeds. During remote control operation the scaled vehicle is capable of continuously maintaining and varying the individual wheel speed and individual wheel steering angles of all eight wheels in real time. Several steering scenarios have been developed including traditional (front 2-axle steering), fixed third axle (first, second and fourth axle steering), all wheel steering and crab steering (all wheels are parallel with same steering angle). The traditional, two axle steering scenario is experimentally tested for accuracy in this work with planned future research for experimental analysis of the other steering configurations.
This work is conducted using Arduino software to control the physical SECV and TruckSim software to simulate the dynamics of the vehicle. The results obtained from the physical testing of the wheel angular velocity were validated using a handheld tachometer device. The steering angle measurement of each wheel was validated using linear actuator sensors. It was seen that the physical results from the SECV are within acceptable range of the theoretical data calculated and simulated in Trucksim Software. The continuous steering method is applied by investigating the relationship between the steering angles of all eight wheels while operating the steering system from zero to the maximum steering angle of the 1st axle inner wheel during a turn. A major contribution of this work is a novel physical experimentation of the continuous Ackermann relationship for eight wheels. During testing of the traditional two-axle steering configuration the metrics of performance that were reviewed include: wheel speed, center velocity, yaw rate, and eight-wheel steering angles. With these metrics being compared with the Trucksim simulation, the experimental results obtained from the scaled 8x8 electric combat vehicle are a solid foundation for the development of future full-size 8x8 electric combat vehicles.