Robotic platform with wheeled legs and virtual differential transmission

Robotic vehicle apparatus comprising:

• a platform having a left side and a right side, said left side including:
• a left-side motor,
• a left-side axle operatively connected to said left-side motor,
• a left-side rotational sensor operatively connected to said left-side motor or to said left-side axle, the left-side rotational sensor operable to provide a left-side angular position value in the range of 0 to n, and
• a left-side wheel operatively connected to said left-side axle, the left-side wheel having a self-repeating pattern around its outer circumference that repeats m times, the left-side wheel being operable to rotate in 1:1 synchrony with the left-side motor;
• said right side including:
• a right-side motor,
• a right-side axle operatively connected to said right-side motor, a right-side rotational sensor operatively connected to said right-side motor or to said right-side axle, the right-side rotational sensor operable to provide a right-side angular position value in the range of 0 to n, and
• a right-side wheel operatively connected to said right-side axle, the right-side wheel having a self-repeating pattern around its outer circumference that repeats m times, the right-side wheel being operable to rotate in 1:1 synchrony with the right-side motor;
• a forward-facing image sensor fixedly mounted on the platform;
• an arm mounted on the platform, the arm comprising:
• at least two rotatable joints providing for controllable movement in at least two independent axes,
• at least one extendable section, and
• at least one hook;
• a programmable computer including a processor, a wired communication interface, a wireless communication interface, and a nonvolatile electronic data storage medium, the nonvolatile electronic data storage medium comprising executable instructions that when executed by the processor cause the robotic vehicle, under direction and control of the processor, to perform steps comprising:
• initializing the left-side rotational sensor to produce a first left-side angular position value of 0,
• initializing the right-side rotational sensor to produce a first right-side angular position value of 0,
• receiving a movement command,
• selectively driving at least one of the left-side motor or the right-side motor in accordance with the movement command,
• obtaining a second left-side angular position value from the left-side rotational sensor and a second right-side angular position value from the right-side rotational sensor,
• calculating an absolute difference between the second left-side angular position value and the second right-side angular position value,
• calculating an angular offset value equal to the absolute difference modulo ((n+1)/m),
• comparing the angular offset value to a threshold,
• if the angular offset value exceeds the threshold, selectively driving at least one of the left-side motor or the right-side motor in an amount proportional to the angular offset value, and
• repeating the obtaining, calculating, and comparing steps zero or more times until the angular offset value is below the threshold, thereby maintaining the sell-repeating patterns on the left-side wheel in relative alignment with the self-repeating pattern on the right-side wheel;
• and
• a rechargeable electric energy storage device with a capacity to power the programmable computer, left-side motor, and right-side motor for at least fifteen minutes.