WOLFRAM SYSTEM MODELER

JoystickReturnTrajectory

Model simulating response of three joystick designs to circularly varying test force

Diagram

Wolfram Language

In[1]:=
SystemModel["EducationExamples.MechanicalEngineering.Joystick.JoystickReturnTrajectory"]
Out[1]:=

Information

This model compares the return trajectory of three analog joysticks after being suddenly released after being displaced from the center equilibrium position. Each joystick has a handle re-centering mechanism based on a symmetrical arrangement of a different number of tension springs.

The other model in this example is JoystickForceResponse, which compares the response of the three joysticks to a circularly varying test force.

Hierarchical Modeling

The joystick model is constructed hierarchically. Double-click on a component such as fourSpringReturn to see its model diagram. Inside fourSpringReturn double-click on one of the tension springs to see its model diagram, and so on:

hierarchical

Simulation & Animation

To simulate the model and view a 3D animation of it, follow the steps below:

Click the Simulate button:simCenter

Click the Animate button: animate

Use your mouse or trackpad to drag the animation into a good angle, and zoom in with your scroll wheel or by using the trackpad. Then click the play button to play the animation.

Change the Time Scale at the bottom of the animation window to 0.1 to watch the joystick in slow motion.

The animation shows the trajectory of the joystick handle as it springs back after being suddenly released from a position away from the center equilibrium:

Note that the handle does not return along a linear trajectory. The joysticks with a larger number of symmetrically spaced springs (four or six) follow a path that is more nearly linear.

Visualization

After simulating the model, look at the stored plots to see parametric plots of the path along which each joystick returns.

The parametric plots look like this:

hierarchical

You can see that the six-spring arrangement leads to the most linear return trajectory.

By simulating the other model in this example, JoystickForceResponse, you can also obtain the following parametric plots of the response of each joystick to a circularly varying test force:

hierarchical

You can see that the-six spring arrangement leads to the most circular force response.

Parameters (2)

initialAngles

Value: {0.5, 0.1}

Type: Angle[2] (rad)

Description: Initial angles of the joysticks, first rotating aroung the X-axis and then rotating around the Y-axis

springConstants

Value: 100

Type: TranslationalSpringConstant (N/m)

Description: Base spring constant of the joystick springs

Components (23)

world

Type: World

Description: World coordinate system + gravity field + default animation definition

joystickJoint1

Type: JoystickJoint

Description: Two degree-of-freedom joystick joint

bodyCylinder1

Type: BodyCylinder

Description: Rigid body with cylinder shape. Mass and animation properties are computed from cylinder data and density (12 potential states)

bodyCylinder2

Type: BodyCylinder

Description: Rigid body with cylinder shape. Mass and animation properties are computed from cylinder data and density (12 potential states)

threeSpringReturn

Type: ThreeSpringReturn

Description: Joystick re-centering mechanism with three tension springs

fixedTranslation1

Type: FixedTranslation

Description: Fixed translation of frame_b with respect to frame_a

fixedTranslation2

Type: FixedTranslation

Description: Fixed translation of frame_b with respect to frame_a

fourSpringReturn

Type: FourSpringReturn

Description: Joystick re-centering mechanism with four tension springs

bodyCylinder3

Type: BodyCylinder

Description: Rigid body with cylinder shape. Mass and animation properties are computed from cylinder data and density (12 potential states)

bodyCylinder4

Type: BodyCylinder

Description: Rigid body with cylinder shape. Mass and animation properties are computed from cylinder data and density (12 potential states)

joystickJoint2

Type: JoystickJoint

Description: Two degree-of-freedom joystick joint

fixedTranslation3

Type: FixedTranslation

Description: Fixed translation of frame_b with respect to frame_a

joystickJoint3

Type: JoystickJoint

Description: Two degree-of-freedom joystick joint

bodyCylinder5

Type: BodyCylinder

Description: Rigid body with cylinder shape. Mass and animation properties are computed from cylinder data and density (12 potential states)

bodyCylinder6

Type: BodyCylinder

Description: Rigid body with cylinder shape. Mass and animation properties are computed from cylinder data and density (12 potential states)

sixSpringReturn

Type: SixSpringReturn

Description: Joystick re-centering mechanism with six tension springs

fixedTranslation4

Type: FixedTranslation

Description: Fixed translation of frame_b with respect to frame_a

fixedTranslation5

Type: FixedTranslation

Description: Fixed translation of frame_b with respect to frame_a

base

Type: FixedShape2

Description: Visualizing an elementary shape with dynamically varying shape attributes (has two frame connectors)

fixed

Type: Fixed

Description: Frame fixed in the world frame at a given position

fixedTranslation6

Type: FixedTranslation

Description: Fixed translation of frame_b with respect to frame_a

fixedTranslation7

Type: FixedTranslation

Description: Fixed translation of frame_b with respect to frame_a

fixedTranslation8

Type: FixedTranslation

Description: Fixed translation of frame_b with respect to frame_a