This picture shows two of my motors with a controller. The motors as mention above were bought on ebay for 30.00 each. They are brushed DC motors and run on 60 volts peak. up to 8 amps. these are strong stable motors perfect for the job. A few things you need to be aware of when building any electrically powered device driven by motors. one is the voltage you plan on using this gets into available power sources. You have to be able to power your creation once you build it. I choose 60 volt dc because I could easily find a DC power supply for them, or if necessary build one myself. I will show you the power supply later on. You also need to consider the shaft size of the motor. This is important because you need to be able to find a suitable and low cost yet capable gear reduction system for the robot.

I chose to use a 10 to one reduction encapsulated in a planetary arrangement. this gives me great space savings as well as an efficient power out with good torque characteristics. These pictured were found on the internet and brand new cost me 150.00 apiece. Choose wisely when selecting your gear reduction or drive system. I made a mistake when i chose these units they should have been 30 to 1 not 10 to 1 as a result I will need to add a bellows system to help counteract the extra weight to avoid wearing out the motors and burning up the power supply. I will show you how I was able to fix this issue with very little effort though, sometimes you have to roll with the punches to get the job done. My solution was simple yet elegant and effective. I will install the Bellow system once I receive the parts i ordered should be here next week or so.

The last item you need to be aware of when picking a drive system is not only the motor and the transmission but the feedback system needs to be addressed. All robotic mobile systems need feedback otherwise they will not know where they are in relation to a known point, this is key to control of each axis. I have a 5000 count quadrature encoder on each axis this give me with the 10 to one gear reduction over 400000 counts per axis revolution, and as you may know the more resolution you have in your feedback loop the more accurate the robot is going to be. You can see the encoders mounted here in this pic they are located on the end of each motor with the grey cap. Renco makes these encoders.