The I-V characteristic curve shows the current draw versus the voltage. This can be useful in terms of deciding how much power can be allocated to the motor at a certain point. The speed is also directly proportional to the voltage provided. As voltage increases, so does the rpm of the motor. The speed of the motor is important because if they rotate too fast the Biped risks getting off balance. The right amount of current and rpm needed to be selected to pick the right motor for the project. We knew that the 3Dot could provide our robot with 5V and up to 1A, so these specs were taken into account when making the decision. We decided to use the GM-7 motor because it was smaller, used less power, and produced greater torque provided compared to the GM-9.  Another deciding factor to choose the GM-7 motor was the fact that they have models that are manufactured with an extended shaft. The extended shaft can allow for the addition of a shaft encoder which then can be used to help with the motor code and the implementation of a PID controller. The characteristic curves are shown below and are a good indicator of how much power could be allocated.

Figure 1: I-V Curve of GM-7 and GM-9 motors

Figure 2: IV Curve Data