Robotino has a fourth motor output and encoder input for the connection of an additional motor and encoder.
assembly and connection
The motor input and the encoder input are mounted on the power electronics board and can be accessed directly on the front panel of the Robotino charging bay.
Technically, the motor output is realized by a four-quadrant converter (H-bridge), which supplies up to 5 A current. The H-bridge is controlled with a high-frequency PWM signal and a direction bit. The setpoint specified via the input sets the direction bit on the basis of its sign. The magnitude of the setpoint influences the PWM signal. A setpoint of 0 does not generate a PWM signal, i.e. the H-bridge does not supply current. A setpoint value of 50 sets the ratio of high to low within the PWM signal to 50%. A setpoint value of 100 leads to a constant high, i.e. the H-bridge supplies the maximum current.
The microcontroller evaluates the signal at the encoder input (A,B channel Gray code). Both rising and falling edges are taken into account, so that a 4-fold effective resolution of the encoder compared to the nominal encoder resolution is achieved.