Wheel Motor: Unterschied zwischen den Versionen
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File: Pwm_20khz.png | PWM 20 Khz: odometry ticks, sense (current) | File: Pwm_20khz.png | PWM 20 Khz: odometry ticks, sense (current) | ||
File: Pwm_31khz.png | PWM 31 Khz: odometry ticks, sense (current) | File: Pwm_31khz.png | PWM 31 Khz: odometry ticks, sense (current) | ||
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+ | == Motor controller (PID) == | ||
+ | The speed of the motors is controlled by a software PID controller. You can monitor the quality of the motor speed control via pfodApp (Plot->Motor control): | ||
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+ | <gallery> | ||
+ | File: Odometry_motor_pid_controller.png | ||
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Version vom 6. Dezember 2015, 00:10 Uhr
Inhaltsverzeichnis
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.
NOTE: only for demonstration! See real schematics for concrete wiring
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.
Motor controller (PID)
The speed of the motors is controlled by a software PID controller. You can monitor the quality of the motor speed control via pfodApp (Plot->Motor control):
Programming
/!\ work on going !