Potential function control for multiple high-speed nonholonomic robots

Many approaches to the formation control problem for multi-robot systems have been proposed. In distributed consensus algorithm methods, and leader-follower structures the robots are explicitly assigned positions within the desired formation. By contrast, artificial potential function (APF) control generally does not specify a formation explicitly but rather drives the robots down the negative gradient of a potential field such that a formation emerges at a global or local minimum. The ad hoc emergence of the formation has several benefits, especially for a fleet of homogeneous vehicles: It allows for spontaneous adaptation of the formation to addition and removal of vehicles, and it allows for truly homogeneous control for each agent since no hierarchy or unique assignment in a constraint graph is needed. APF methods, however, are generally designed for and tested on robots that approximate fully holonomic double integrator point masses. APF methods designed for nonholonomic robots have been limited to robots with single integrator dynamics or to a single robot traveling at low speed. This video presents the results of an effort to adopt APF methods for high-speed, dynamic, nonholonomic robots. This paper describes the experimental testbed: a fleet of inexpensive 4-wheel drive skid-steered robots called Dynabots capable of speeds up to 10 m/s and accelerations of at least 4 m/s².