Perpendicular-wheeled Ball-Balancing Robot tests
James Bruton, an independent robotics builder, explains how he designed and tested a basketball-sized robot with perpendicular wheels that balance and steer on a ball.
In this talk
- 0:00
Why test a perpendicular wheel
Bruton’s rideable ball-balancing robot was hard to steer, and he had explored ducted fans, reaction wheels, and gyros for yaw control. He builds a smaller basketball prototype to test whether turning one of its three omni wheels sideways can rotate the ball while still driving in two directions.
- 1:32
Build the wheels and electronics
Bruton makes printable omni wheels with TPU rollers, PLA frames, and steel axles, then mounts them with geared motors and encoders. An ESP32 receives remote commands over ESP-NOW, while a BNO086 measures tilt and motor drivers power the wheels. He uses per-wheel PID control to regulate velocity before adding the balancing controller.
- 9:56
Tune balance and increase speed
Bruton sets wheel speed ratios for forward and sideways travel, then uses a PID controller to balance from measured pitch and roll. The small robot jitters and wanders, but adding M20 nuts high on a stick makes it settle more steadily. A faster gear set adds about 50% wheel speed, though it requires retuning the controllers.
- 13:40
Rotation remains unstable
When Bruton commands the sideways wheel to rotate the ball, the robot often falls over, especially at higher speeds. The wheels slip on smooth balls, and gearing up increases backlash; adding integral control to the wheel velocity loops improves stability and responsiveness. Small turns sometimes work, but rotation or combined driving and turning still causes loss of control, and Bruton asks viewers to suggest why.
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