# Differential Driver Actuator: Linear and angular speed (V, W) actuator¶

This actuator reads the values of linear and angular speed and applies them to the robot as speeds for the wheels. It only works with robots of the type WheeledRobot, such as the Segway RMP 400 and the Pioneer 3-DX. The movement of the robot is more realistic, but also depends on more factors, such as the friction between the wheels and the surface.

The speeds for the left and right wheels are calculated as:

left_speed = (v - e w) / R right_speed = (v + e w) / R

where:

• v is the linear velocity given as parameter
• w is the angular velocity given as parameter
• e is half of the distance between the left and

right wheels - R is the radius of the wheels

## Configuration parameters for differential driver actuator: linear and angular speed (v, w) actuator¶

No configurable parameter.

## Data fields¶

This actuator reads these datafields at each simulation step:

• v (float, initial value: 0.0)

linear velocity in x direction (forward movement) (m/s)

• w (float, initial value: 0.0)

Interface support:

## Services for Differential Driver Actuator: Linear and angular speed (V, W) actuator¶

• get_configurations() (blocking)

Returns the configurations of a component (parsed from the properties).

• Return value

a dictionary of the current component’s configurations

• get_properties() (blocking)

Returns the properties of a component.

• Return value

a dictionary of the current component’s properties

• set_speed(v, w) (blocking)

Modifies v and w according to the parameters

• Parameters
• v: desired linear velocity (meter by second)
• w: desired angular velocity (radian by second)
• stop() (blocking)

Stop the robot

Internally, it sets (v, w) to (0.0, 0.0)

## Examples¶

The following examples show how to use this component in a Builder script:

```from morse.builder import *

robot = ATRV()

# creates a new instance of the actuator
motionvwdiff = MotionVWDiff()

# place your component at the correct location
motionvwdiff.translate(<x>, <y>, <z>)
motionvwdiff.rotate(<rx>, <ry>, <rz>)

robot.append(motionvwdiff)

# define one or several communication interface, like 'socket'

env = Environment('empty')
```