Hello all,
I am building my first real robot on my own and am running into some difficulties. I do not know how to choose the correct motor or batteries to use in the robot. I’ve calculated that the robot will be roughly 90lbs and I will be using two motors in order to move it. It operates on three wheels. I have used the sizing calculator on this site and got: Drive Motor Sizing Tool | RobotShop Community
Angular Velocity: 9.000 rad/s
Torque: 1.7018Nm
Total Power: 15.316W
Maximum Current: 0.76582
Battery Pack: 3.8291Ah
I was looking at using a drill motor but I do not know all of the differences or what I should use. Brushless or not brushless? Impact Driver motor? 20VMax batteries?
Compact drill
DEWALT 20V MAX XR Brushless Drill/Driver, Compact - Bare Tool (DCD791B)
Impact drill
DEWALT 20V MAX XR Impact Driver, Brushless, 3-Speed, 1/4-Inch, Tool Only (DCF887B)
Compact 20VMax batteries (2Ah)
DEWALT 20V MAX Battery, Compact 2.0Ah Double Pack (DCB203-2), Yellow
20V max Batteries (5Ah)
DEWALT 20V MAX XR 20V Battery, 5.0-Ah, 2-Pack (DCB205-2)
I also do not know what to get as a motor controller. If there are any suggestions for controlling drill motors that would be much appreciated.
In order to buy a suitable brushed DC motor driver, you need to know the stall current specification for the motor, as the driver MUST be able to handle it.
The stall current is very high for drill motors (I've seen anecdotal reports of 20 to 50 Amperes), but I think you will find it difficult or impossible to find manufacturer specifications for them.
Most people buy motors from a robotics supplier, like Pololu, Servocity, Tower Hobby etc. as that way you know what you are getting. Those suppliers also have suitable shaft adapters, gearboxes, etc. to match. You could also consider using an electric motor and the matching controller from a kid's scooter.
You'll need a substantial gear ratio to get the wheel shaft speed down to 9 rad/sec (85 RPM).
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