James Bruton Prepares to Build a Ridable Robot Centipede

Everyone loves an unusual vehicle and few vehicles are more unusual than gigantic ridable robot centipedes. James Bruton, a world-renowned unusual vehicle enthusiast, plans to build that ridable centipede. But every good engineer knows that it is wise to test new ideas at a small scale first, before committing the time, money, and resources to the full-size project. To follow that wisdom, James Bruton constructed this large (but not quite ridable) robot centipede.

"Centipede" is a bit of a misnomer, as this robot only has 10 legs on each side (for a total of 20). But that isn't as far off as you'd think. Despite the word "centipede" literally meaning "100 legs," actual centipedes can have far fewer than that (orfar more). Some have as few as 15 pairs of legs, so this robot is pretty close.

Etymological musings aside, this is a robot with five body segments. Each of those segments contains four legs. Those legs are all interconnected via a central spinning gear and linkages between the pair of legs on the same side. The legs on opposite sides are timed 180 degrees apart, so the forward leg on the left side makes contact with the ground at the same time as the back leg on the right side. Segments do not have their own dedicated motors. Instead, one segment has a drive motor and transfers power to the other segments through a series of universal joints. Each pair of segments is connected by an additional universal joint that constrains movement to horizontal pivoting and vertical pivoting, preventing twisting.

Steering is accomplished with two servo motors on the leading segment. Those pull on elastic cords that connect to the second segment. Tightening the left cord forces the front segment to turn left and the other segments follow, and vice versa. An Arduino Mega 2560 development board controls the drive DC motor and the two servo motors. Power comes from a hobby LiPo battery pack. Bruton can pilot the centipede robot using his universal remote that we featured recently.

This scale prototype works, but not as well as Bruton would have liked. The movement isn't very efficient, as the linkages cause the legs to slide backward. This is why it is a good idea to start at a small scale before attempting the final project. Now Bruton knows that he needs to revise the leg mechanisms and he is considering taking inspiration from strandbeests—massive walking machines that move so smoothly that they don't need motors at all.