Wheel Motor

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Wheel motors caracteristics & driver

The two left and right gear motors are controlled independently (aka 'differential driving') to:

  • drive the robot forward/backward
  • steer the robot left/right

The Ardumower wheel motor features:

  • A rotation speed up to 31 rpm allows to move the robot at sufficient speed (at up to meter/sec = 31rpm/60 * PI * 0.25m = 0.4m/sec using 250mm diameter wheels)
  • A high torque (2.45Nm) guarantees that the robot can climb small hills as well (with 2 motors, 0.125 radius wheel, 31rpm = 0.4m/s, acceleration = 0.2 ( 1/2 of nomeinal speed) up to 14 degree) see calculator
  • Integrated encoders, so it can measure the rotation speed, the distance and the direction (see Odometry for more information) - Encoders are REQUIRED for Ardumower software.
  • 24V (load current ~1A)

Wiring

One pin controls the direction (forward/backward), the other pin controls the speed. One analog input pin is connected to the current sensor. The current sensor module (ACS712-05A) is connected in series with the motor.

Protection board is advice to be used between controler and motor.

Control principal : PWM frequency

The speed of the motor is controlled by a PWM duty signal. We use the Arduino default PWM frequency (490 Hz) to control the motor drivers.

Programming

/!\ work on going !