The object of the robot is manetaining a constant speed & heading on its own. This is just automated enough for a lion to drive it with 1 paw. The journey began in Jan 2014, with a $40 G-Buggy the lion kingdom got for free:
It was a very poor at setting a pace, couldn't carry cargo, but could carry a camera. There was no easy way to measure speed & the steering was binary. With enough tuning however, the steering could be made proportional enough to hold a heading.
The steering mechanism was an interesting reduction of a servo into a spring that centered the wheels & a clutch plate that applied a steering force proportional to the speed of a motor. The controller it came with could only do binary steering, but with a fast rate sensor & feedback loop, the steering could be made somewhat proportional.
The inner clutch plate & outer ring it pressed against while spinning, but not while stationary.
With a constant voltage applied to the traction motor, it achieved poor speed regulation but infinitely better than lions trying to pace themselves.
The final form of the 1st model.
Several models came afterwards, as budgets increased, culminating in the Tamiya Lunchbox. The steering was finally proportional & the speed could finally be regulated.
Attempts to make it self driving all failed, for reasons startups are too familiar with.
Key to making it all work was a paw controller. Proportional steering & throttle would be nice, but weight & durability dictated binary tact buttons. China simply never made a durable, compact, proportional sensor.
The final design had 2 buttons for slow steering, 2 buttons for fast steering, 1 button for throttle. This was proportional enough for all needs, with the computer automating speed & heading. 1 switch controlled reverse.