Formation Control of Agricultural Mobile Robots: A Bidirectional Weighted Constraints Approach

Abstract

AbstractThis paper focuses on the formation control of several mobile robots in off‐road conditions. A control strategy based on bidirectional referencing is proposed, where each robot combines a velocity control w.r.t. the immediate preceding neighbor with a control w.r.t. the immediate following neighbor. Two virtual leaders, respectively, at the head and at the tail of the fleet, are propelling the fleet at the desired velocity. The fleet stability is investigated using Lyapunov techniques, pending on combination coefficients. The stability is theoretically proven for constant coefficients as weights of the respective velocity controls and tested through simulations and full‐scale experiments. It is shown that this control strategy permits us to reduce the error propagation problem often encountered in formation control, while limiting the communication problems of the global strategies. As a result, a stable formation control architecture is defined, which requires each vehicle to be refereed only to two other robots. This limited communication need is particularly interesting for agricultural operations. The proposed approach is implemented in this paper on agricultural tractors.