  This paper presents a systematic design of an active disturbance rejection
control (ADRC) system for unmanned tracked vehicles (UTVs) in leader-follow
formation. Two ADRC controllers are designed for the lateral and the
longitudinal channels of the UTV based on control errors in the cross-track and
the along-track directions. Through simulations, the proposed ADRC approach is
first shown to outperform the conventional PI/PID controllers in scenarios
involving sudden changes in the leader motion dynamics, slippage disturbances,
and measurement noise. Then, a comprehensive experimental validation of the
proposed leader-follower control is performed using a laboratory UTV equipped
with a camera and laser sensors (to enable the calculation of error signals).
In order to provide more effective interaction between the human (leader) and
the UTV (follower) during the leader-follower task, a camera-based subsystem
for human pose recognition is developed and deployed. Finally, the experimental
results obtained outdoors demonstrate that the proposed ADRC-based
leader-follower UTV control system achieves high tracking capabilities,
robustness against slippage disturbances, and adaptability to changing
environmental conditions.
