I am currently in the process of building a robot and I am unsure about what type of motors to get. The robot is one that will perform a wall following program and should have a reasonable torque and RPM.
I am using an Arduino Mega with a Motor shield v2.3. I am sure that I am going to use DC brushed motors and not stepper motors. I currently have a robot that with the chassis and all the equipment installed will weigh upwards of 25 lbs.
My wheels are 4 inches in diameter. From this I calculated a stall torque of 800 so to be safe I thought to get a motor with at least 900 oz-in. I have two wheels which both need motors and 2 ball bearings up front.
When browsing this site I found some motors: robotshop.com/en/198rpm-1200 … motor.html and robotshop.com/en/banebots-81 … r-kit.html
What exactly are he differences between these two motors. Does anyone have any better suggestions?
My project is to create a robot that with using ultrasonic sensors will perform a wall following program.
I am a Computer Science student so I am very new to this area and would appreciate some feedback. Thank you.
From what I can tell, the first motor will be out of the box to use whereas the second one requires you to assembly a metal gearbox. My background is in mechatronics engineering and from the gear boxes I have made, the challenges are making very accurate measurements to ensure the gearbox is smooth. A gearbox that is poorly assembled can break and cause damages to the motor it is connected to.
I don’t have any good suggestions except to make sure you power your motors separately from your logic. One word of advice is, I have utilized ultra sonic sensors for a similar robot before and they have one drawback.
If the wall / surface you are following has irregular shapes, it will cause you a lot of grief. Ultrasonic sensors get a lot of noise if the surface is not smooth. In my case, I made an maze solving robot that solves any size maze and redraws the shortest path afterwards. The problem was, if the maze had irregular shapes on the wall, the robot will think it has decided a turn when it was just a bump on the surface (adding buffer logic helped but it made the robot inconsistent).
If you calculated that the maximum continuous torque you will need will be 800oz-in, then the stall torque of the motor you select should be at least 4-5x this value.
Stall torque is the value when the shaft of the motor is no longer able to rotate and will burn up very fast. RB-Rbo-49 has a stall torque of 39.48oz-in, so the max continuous torque it can provide is 1/5 to 1/4 this value (8-10oz-in).
Multiplied by 81, the max continuous torque after the 81:1 gear down is ~810 oz-in.
