Abstract
Multiple robots can be tele-operated by a single operator to accomplish complicated tasks such as formation and co-transportation. Such systems are challenging because one operator needs to simultaneously tele-control multiple homogeneous and even heterogeneous robots. Besides, the communication between the operator and multi-robot system and the communication among the multiple robots are always subject to some communication constraints such as time delays. This chapter introduces a novel non-time based method to realize the single-operator-multi-robot (SOMR) teleoperation system with random communication delays. The problem is divided into a typical teleoperation problem and a multi-robot coordination problem. A non-time variable is taken as the system reference instead of the time to model and drive the system such that the random communication delays and some expected events could be automatically handled. Experiments implemented on a multi-robot system illustrate the effectiveness and advantages of the method.
TopBackground
Some recent studies have been conducted on the control of multiple robotic systems by a single operator in various situations.
In (Suzuki, Sekine, Fujii, Asama, & Endo, 2000) and (Reinoso, Gil, Paya, & Julia, 2008), the multi-robot system was assumed to be highly autonomous. The operator sent high-level task formation control commands to multi-robot system, which were then carried out autonomously by the multi-robot system. The operator supervised the multi-robot system and sent commands by using the shared natural language when he/she thought it was necessary. This approach highly relied on the autonomy of the robots and its lack of safety.
A semi-autonomous bilateral tele-operation framework for the SOMR system was proposed in (Lee, Martinez-Palafox, & Spong, 2005) and (Lee & Spong, 2005). The dynamics of the multiple slave robots were decomposed into two decoupled systems while enforcing energetic passivity. The first system is the shape system, which describes the cooperation aspect such as formation keeping. The second system is the locked system, which abstracts the overall behavior of the multiple slave robots. By locally controlling the decoupled shape system, secure and tight cooperation such as formation control could be achieved.
In (Preeda, Hwang, & Hashimoto, 2006), wave variable based method was applied in simulation for nano SOMR tele-operation, where an operator could take control of the master device to control and manipulate the nano/bio object by using multiple nano-manipulators in the remote area over the delayed network.
Key Terms in this Chapter
Coordination: A control approach to simultaneously control multiple robots in a multi-robot system to achieve certain multi-robot tasks such as trajectory tracking with a given formation.
Teleoperation: An approach to enable human operators to control robotic systems from a distance over the communication networks.
Mobile Manipulators: A type of robotic systems which contain both mobile platforms and manipulators.
Formation Control: A control approach with the goal to achieve certain formations with a group of robots.
Operators: Humans who can control the robotic systems using some specific tools such as joysticks.
Multi-Robot Systems: A system consisted of multiple robots which can cooperate and communicate with each other to accomplish certain tasks.
Single-Operator-Multi-Robot (SOMR) Systems: A teleoperation system which contains one single operator and multiple robotics systems.