Arduino Lawn Mower Project

Hello everyone,

This is my first time posting on the Arduino forums. I am working with a group on a capstone project to turn an electric lawn mower into a lawn mowing robot. The base of our project is the Greenworks 25272 mower, which you can see here: http://www.sears.com/shc/s/p_10153_12605_07189543000P?adcell=P1_mowerfinder . My job is to figure out how to move the mower straight and make turns.

The mower comes with a setup for self-propelling which amounts to pulling a lever to control a gearbox on the back axle. Our plan at the moment is to remove the rear axle and gearbox and instead attack a motor to each wheel, allowing us to move straight or turn. So far we've purchased one DC motor (Ampflow E30-400: http://www.ampflow.com/three_inch_high_performance_motors.htm ) and an Arduino motor shield (http://arduino.cc/en/Main/ArduinoMotorShieldR3 ). According to the information on the motor shield we can drive 2 motors, but our motors require a much larger voltage than the recommended supply.

My questions at the moment are: 1. Should we be using DC motors? We also have the option of using stepper motors, which I understand are more precise because we can control the rotations. 2. Do we need to purchase a controllable power supply, or will a battery work fine? If anyone has any experience with projects like this please feel free to offer any advice you might have. At the moment I am trying to figure out exactly what parts we need to get the mower moving. Thank you!

Hi, and welcome to the forum.

The link to the lawn mower doesn’t work all the time. It is the result page of a search.
I hope this one works: http://www.sears.com/greenworks-25272-36v-lead-acid-cordless-19inch/p-07189543000P

The battery is 36Volts, but that motor shield can only go up to 12V.
The motors are about 30A at peak performance, the stall current might be more, but that motor shield can only do about 3A.
That motor shield is for a simple stepper motor, or for a toy car. Not for serious power.

Can you find the stall current for those motors ?
You have to find a motor driver board that can deliver enough power.

Stepper motors are not powerful, you need DC motors.
Can you use a motor for 36V ? and use the battery of the lawn mower ?

There is something you need to think about: If the lawn mower is running on its own, it will not keep a straight line. You might need a IMU (gyroscope, accelerometer, compass) or GPS to keep it straight.