TRI-STAR WHEEL LOCOMOTION – 21142
A unique and versatile method of robot propulsion uses sets of wheels arranged in triangles. The geometry of the wheel sets has given rise to the term tri-star wheel locomotion. A robot can have three or more pairs of tristar wheel sets. The illustration shows a robot with two sets. (This drawing shows only one side of the machine. An identical pair of tri-star wheels exists on the other side, out of sight in this perspective.)
Each tri-star set has three wheels.Normally, two of these are in contact with the surface. If the robot encounters an irregularity in the terrain, such as a big pothole or a field of rocks, the tri-star set rotates forward on a central bearing. Then, for a moment, only one of the three wheels is in contact with the surface. This might happen once or repeatedly, depending on the nature of the terrain. The rotation of the central bearing is independent of the rotation of the wheels.
Tri-star wheel locomotion works well for stair climbing. It can even allow a robot to propel itself through water, although slowly. The scheme was originally designed and patented by Lockheed Aircraft. Tri-star wheel locomotion is applicable to use by remotely controlled robots on the Moon or on distant planets.