Grin-Dal. ( Grinder/pedal ).
Unzip it, get in, pedal forwards to go forwards, pedal backwards to go backwards.
Grind right grinder, to go right.
Grind left grinder, to go left.
Brakes on the grinder handle bars.
Two belts to move the ball, on the outside of the ball, activated by the pedals & grind, handle bars.
The design of it will be the focus to, design it with Belt(s), so that it stays in the direction that the user wants it to move etc.
In the making, brief description, use your imagination.