On the Robust Longitudinal Trajectory Tracking for Load Transportation Vehicles on Uneven Terrains The longitudinal trajectory tracking for small Unmanned Ground Vehicles (UGVs) subject to realworld disturbances is addressed, by considering an anisotropic ground friction and the variation of its own mass during transportation. A methodology was proposed to perform the design of the controller in the ProportionalIntegralDerivative (PID) format, which is robust to parametric uncertainties and minimizes output disturbances. Next, a small ground platform for load delivery tasks has been developed, equipped with lowcost navigation sensors and onboard computers. Finally, simulated and realworld experiments illustrate the effectiveness of this application under different scenarios, by combining distinct conditions of friction, payload, and terrain profiles.

Smooth Trajectory Tracking Using Longitudinal Distance Constraint for A 4WS4WD Unmanned Ground Vehicle The modelbased trajectory tracking method of four wheel steering and four wheel drive (4WS4WD) unmanned ground vehicles (UGVs) needs to establish accurate vehicle kinematics and dynamics models, which is computationally complex thus functioning poorly in realworld scenarios. The geometrybased method, i.e., the pure pursuit method, uses the position information to regulate vehicleu0027s steering angle, which has good realtime performance in practical applications. However, the existing pure pursuit method only considers the lookahead distance constraint, ignoring the influence of the longitudinal distance which affects the smoothness of the vehicle trajectory. It may cause the vehicle to oscillate back and forth around the target trajectory. This work proposes an improved pure pursuit method with longitudinal distance constraint (LDC) to avoid the vehicle oscillation effectively. Additionally, to alleviate the cornering cutting problem, a fuzzy logic based controller is proposed to dynamically adjust the lookahead distance according to the curvature. A comparative experiment between the proposed method and the conventional pure pursuit method was conducted. Results show that the proposed method has better trajectory smoothness and tracking accuracy than the traditional pure pursuit method.