Discussion on: “Adaptive and Predictive Path Tracking Control for Off-road Mobile Robots”

The authors are addressing the problem of accuratepath tracking in off-road terrains in presence oflateral sliding, with particular application to agri-culture vehicles. The adherence conditions are notmodeled explicitly (i.e. no tire to ground model),however the lateral sliding angles of the wheels areintegrated in the kinematic bicycle model, calledextended kinematic model. An observer is used toestimate the unknown sliding angles on-line withrespect to steady-state adherence conditions. A steer-ing wheel controller based on chained form trans-formation of the kinematic bicycle model for theparametric curve tracking is used. Furthermore, inorder to compensate for abrupt curvature changesand low level control delay, a model predictive con-trol signal is added. Experimental verification isprovided on slippery, wet ground for straight driv-ing on a slope and curved path driving on flat ground,with good tracking results achieved, close to setrequirements.