...
This angle was then used as the "input" for conducting the rest of the position analysis.
Figure 7: Sketch of the handle input.
...
Figure 9: Sketch of the gear mechanism. R4 and θ4 belong to the input gear, R5 and θ5 belong to the intermediate gear that turns the wheels. R6 and θ6 are the distance and angle of the vector from the center of the front wheel to the "foot".
...