This robot is called 1STAR, for “1 actuator STeerAble Robot.” Even though it has six legs, and it can controllably move and turn both left and right, it manages to do it with one single motor. Just one.
The robot’s legs make contact with the floor in a tripod pattern. At a given point in time, one front and one rear leg are touching the floor, along with one middle (compliant) leg on the opposite side. If the robot accelerates, the compliant leg bends while the rigid legs don’t, and the robot will turn towards the compliant side, since the bending leg doesn’t move as far. If the acceleration of the robot remains constant, this will happen on each stride, and the robot will move forward. If, however, the robot only accelerates when the compliant leg on one side is touching the floor, and then decelerates when the compliant leg on the other side is touching the floor, it’ll turn in one direction. Switch up the acceleration and deceleration, and the robot will turn in the other direction. These changes in acceleration happen fast enough that you can’t see it as the robot moves, but as the video shows, the robot is easily capable of avoiding obstacles.
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