Details below come from 

Move Steering

class ev3dev2.motor.MoveSteering(left_motor_port, right_motor_port, desc=None, motor_class=<class 'ev3dev2.motor.LargeMotor'>)

Bases: ev3dev2.motor.MoveTank

Controls a pair of motors simultaneously, via a single “steering” value and a speed.

steering [-100, 100]:

• -100 means turn left on the spot (right motor at 100% forward, left motor at 100% backward),
• 0 means drive in a straight line, and
• 100 means turn right on the spot (left motor at 100% forward, right motor at 100% backward).

“steering” can be any number between -100 and 100.

Example:

steering_drive = MoveSteering(OUTPUT_A, OUTPUT_B)
# drive in a turn for 10 rotations of the outer motor
steering_drive.on_for_rotations(-20, SpeedPercent(75), 10)

on_for_rotations(steering, speed, rotations, brake=True, block=True)

Rotate the motors according to the provided steering.

The distance each motor will travel follows the rules of MoveTank.on_for_rotations().

on_for_degrees(steering, speed, degrees, brake=True, block=True)

Rotate the motors according to the provided steering.

The distance each motor will travel follows the rules of MoveTank.on_for_degrees().

on_for_seconds(steering, speed, seconds, brake=True, block=True)

Rotate the motors according to the provided steering for seconds.

on(steering, speed)

Start rotating the motors according to the provided steering and speed forever.

get_speed_steering(steering, speed)

Calculate the speed_sp for each motor in a pair to achieve the specified steering. Note that calling this function alone will not make the motors move, it only calculates the speed. A run_* function must be called afterwards to make the motors move.

steering [-100, 100]:

• -100 means turn left on the spot (right motor at 100% forward, left motor at 100% backward),
• 0 means drive in a straight line, and
• 100 means turn right on the spot (left motor at 100% forward, right motor at 100% backward).

speed:

The speed that should be applied to the outmost motor (the one rotating faster). The speed of the other motor will be computed automatically.

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Units

Most methods which run motors will accept a speed argument. While this can be provided as an integer which will be interpreted as a percentage of max speed, you can also specify an instance of any of the following classes, each of which represents a different unit system:

class ev3dev2.motor.SpeedValue

A base class for other unit types. Don’t use this directly; instead, see SpeedPercent, SpeedRPS, SpeedRPM, SpeedDPS, and SpeedDPM.

class ev3dev2.motor.SpeedPercent(percent, desc=None)

Speed as a percentage of the motor’s maximum rated speed.

class ev3dev2.motor.SpeedNativeUnits(native_counts, desc=None)

Speed in tacho counts per second.

class ev3dev2.motor.SpeedRPS(rotations_per_second, desc=None)

Speed in rotations-per-second.

class ev3dev2.motor.SpeedRPM(rotations_per_minute, desc=None)

Speed in rotations-per-minute.

class ev3dev2.motor.SpeedDPS(degrees_per_second, desc=None)

Speed in degrees-per-second.

class ev3dev2.motor.SpeedDPM(degrees_per_minute, desc=None)

Speed in degrees-per-minute.

Example:

from ev3dev2.motor import SpeedRPM

# later...

# rotates the motor at 200 RPM (rotations-per-minute) for five seconds.
my_motor.on_for_seconds(SpeedRPM(200), 5)