Currently, I am in the process of designing a robot which will have "surveillance" purposes- generic observations through a wireless webcam. The technical aspects of the transmitting device have been worked out- however, the chassis is a different story. Specifically the locomotion of the bot- it will be making quite a few turns, and will be navigating high-traffic areas (hallways, classrooms). In addition, the final design will weigh about 30 pounds. The dimensions of the base are approximately 24" by 18". The wheels themselves are a bit oversized with a diameter of 1 foot, each. Four wheels will be used, and the two on each side (right, left) will be connected (so that they spin together). Two motors will be used- one per side, to enable differential steering. However, the current problem is on braking.
Basically, I do not know how to proceed with the braking system. Every other schematic has been thought out of- but there seems to be a major problem. I would like to use frictional braking, however, I do not know how to implement it. Should a locking system be used that LOCKS the wheel in place (though the vibrations may damage the equipment on board), or should enough force be applied by a high-torque motor of some sort that pushes rubber upon rubber? Or should it go far enough to push a pad of rubber against the ground, providing great friction and vibration? Or was something overlooked, and that a MUCH more efficient method exists? Moreover, I would like to emphasize that simply stopping the flow of current to the motor will not suffice- some sort of direct braking mechanism is definitely needed.