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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

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