Multi-Robot Object Manipulation Using Cluster Space Control

IGNACIO MAS; CHRISTOPHER KITTS

Santa Clara

Congreso; 2010 ASME Information Storage and Processing Systems Conference; 2010

ASME

Large object transportation and manipulation of objects in hazardous environments are tasks that can be benefited from the utilization of groups of mobile robots working in a cooperative fashion.  The group surrounds or traps the object of interest and then transports it to a desired destination by applying pushing forces upon it. A multi-robot formation control framework is necessary to coordinate the motions of the robots in the formation. Reports in the literature show different techniques implementing this task, using different approaches from lead-follower configurations to potential field-based entrapments. In this article, a particular formation control approach called Cluster Space Control framework is utilized to control a group of four non-holonomic wheeled robots. A single operator using a joystick input controls the position of all the robots in the formation. This is made possible by the level of abstraction introduced by the control framework, which allows for simple specification, control and monitoring of the formation position, orientation and shape. In this work, we first present the application of the cluster space framework to the definition of a four-robot formation and show how it is used in a closed loop controller that facilitates a pilot to appropriately control all the degrees of freedom of the group. Then, two different tasks are performed using a Matlab/Simulink  testbed simulator in order to validate the technique. In the first task, a pilot or operator drives the formation to the position of an object. Then the robots entrap the object and apply forces to it to transport it to a desired destination. In the second task, the operator conducts the formation to surround the object and generates a formation trajectory that produces a rotation of the object. A discussion of the results reveals the advantages of using the Cluster Space Control framework to conduct this task, showing that only one pilot is required to perform the complex simultaneous motions of four non-holonomic mobile robots. The approach is also contrasted with others found in the literature.