Motor to Position
Here is some code to move a motor to specific positions (relative to where it is now).
#!/usr/bin/python3
from time import sleep
def main():
position1 = 720 # forward two full rotations
speed1 = 400
position2 = -360 # backward one full rotation
speed2 = 200
# set up the motor
ev3 = Device('this')
m = ev3.LargeMotor('outB')
# run to position 1
print('Going to Position 1: ' + str(position1))
m.run_to_rel_pos(position_sp=position1, speed_sp=speed1, stop_action="hold")
# wait till done moving (keep checking)
while m.is_running:
sleep(0.1)
# wait 1/2 second before moving to next position
sleep(0.5)
# run to position 2
print('Going to Position 2: ' + str(position2))
m.run_to_rel_pos(position_sp=position2, speed_sp=speed2, stop_action="hold")
# wait till done moving (keep checking)
while m.is_running:
sleep(0.1)
# "relax" the motor at end of the program
m.stop(stop_action="coast")
if __name__ == '__main__':
main()
This uses _run_to_relpos. There is also a _run_to_abspos function.
This also uses a "while m.is_running: sleep(0.1)" trick to wait until motor stops running. Note there is also a "m.wait_while('running')" command that might work instead.
More on the ev3dev Python motor functions: