The Tethered Robot Problem

Abstract

Robot vehicles tethered to fixed bases move about in a common region. To perform its task, each vehicle must visit a prespecified set of locations. This paper discusses the problem of controlling the vehicles so that they do not tangle their tethers. The problem arises, for example, in connection with small air-bearing supported vehicles used to fetch parts for mechanical assembly. The tethers in this case are "umbilical cords" carrying compressed air, power, and signals.The tethered robot problem can be seen as a special case of the general problem of scheduling the motions of several cooperating robots. In more conventional cases the robot's manipulator is connected to the base by a series ofjointed members whose movements in 3D space are quite complicated. The tethered robot problem considered here is much simpler because the manipulators (vehicles) move in only two dimensions, and they are connected to their bases in the geometrically simplest way. Relatively large numbers of tethered robots may be able to share a common space without undue complication. Such sharing can greatly increase the efficiency and flexibility with which an array ofprocessing equipment can be used.The technical problem outlined above leads in particular to the following mathematical problem: identify those rectilinear drawings ( plane embeddings) of the complete bipartite graph K m,n whose edges can be colored with n colors so that no two edges of the same color have common points (including endpoints). Solutions are presented for useful special cases. The general case of this apparently new problem remains open.

Navi-Guider: An Intuitive Guiding System for the Mobile Robot

“…Actually it has been introduced in a number of publications. From a literature search, we can see that the idea of using tether for a robot control was given in [6] for the first time. In [6], a problem of not tangling tethers was discussed.…”

“…From a literature search, we can see that the idea of using tether for a robot control was given in [6] for the first time. In [6], a problem of not tangling tethers was discussed. In [7], a shortest path planning when a robot is connected by a tether was discussed, and in [8][9], some ideas of using tether for robot guidance were introduced.…”

“…In [10], a virtual tether concept was introduced for the first time for a map construction. In [11], a similar tethering problem as [6] was solved in three dimensional space, and in [12][13], applications of tether for a ground robot and an under water robot were presented. Particularly, a concept of robot cooperation using tether was introduced in [13], which is very similar to the cooperation of cliff-robots.…”

Human-Robot Interactive Guiding System's Application in Sonar Quick Mapping

“…There are no studies of quick mapping with a sonar sensor in the mobile robot navigation. This paper, therefore, develops the quick mapping methods using Navi-guider, which is one of the tethered-robot cabling systems [12][13][14][15][16][17][18]. Navi-guider has a advantage that it is a easily control the robot, but the robot moving direction sonar sensors have a false measured range because Navi-guider user is most likely to include its beam aperture.…”

Cooperative multi-agent mobile sensor platforms for jet engine inspection - concept and implementation

“…Tethers add a great deal of structure to the problem because they create constraints that limit the freedom of movement of the agents and require additional path planning [18]. This structure works against the spirit of the swarm intelligence, but provides an opportunity to develop the path planning aspect of the technology.…”