The buttons on the m3pi expansion base and on the 3pi base are momentary push buttons. When the robot is off, pushing the power button turns it on. When the robot is on, pushing the power button turns it off. I have been studying your schematic trying to determine what circuitry accomplishes this task. It seems as though the momentary push button switch operates in a toggle manner.
I need to add a power switch to the 3pi. I have created a plastic frame that fits over the 3pi. The plastic frame is inserted into a stuffed animal to give the appearance of the animal moving around. Placing my frame over the base does not allow me to easily access the on/off switch. I wish to connect another on/off switch to the m3pi with longer wires so the switch resides inside the stuffed animal and can easily be turned on/off.
Understanding how you provide power with the momentary push button will help me determine how to correctly wire a new switch.
Diane