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Unicycle Kinematic Model

Compute vehicle motion using unicycle kinematic model

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  • Unicycle Kinematic Model block

Libraries:
Robotics System Toolbox / Mobile Robot Algorithms

Description

The Unicycle Kinematic Model block creates a unicycle vehicle model to simulate simplified car-like vehicle dynamics. This model approximates a vehicle as a unicycle with a given wheel radius, Wheel radius, that can spin in place according to a steering angular velocity, ω.

Unicycle kinematic model diagram with x, y, theta, velocity, steering velocity and wheel radius labeled

Examples

Plan Path for a Unicycle Robot in Simulink

Plan Path for a Unicycle Robot in Simulink

Plan an obstacle-free path for a unicycle robot in Simulink® with probabilistic roadmap (PRM) planning and Pure Pursuit control.

Ports

Input

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Angular velocity of the wheel in radians per second.

Dependencies

To enable this port, set the Vehicle inputs parameter to Wheel Speed & Heading Angular Velocity.

Vehicle speed, specified in meters per second.

Dependencies

To enable this port, set the Vehicle inputs parameter to Vehicle Speed & Heading Angular Velocity.

Angular velocity of the vehicle, specified in radians per second. A positive value steers the vehicle left and negative values steer the vehicle right.

Output

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Current xy-position and orientation of the vehicle, specified as a [x y theta] vector in meters and radians.

The linear and angular velocities of the vehicle, specified as a [xDot yDot thetaDot] vector in meters per second and radians per second. The linear and angular velocities are calculated by taking the derivative of the state output.

Parameters

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Type of speed and directional inputs to control the vehicle. Options are:

  • Vehicle Speed & Heading Angular Velocity — Vehicle speed in meters per second with a heading angular velocity in radians per second..

  • Wheel Speed & Heading Angular Velocity — Wheel speed in radians per second with a heading angular velocity in radians per second.

The wheel radius of the vehicle, specified in meters.

The minimum and maximum wheel speeds, specified in radians per second.

The initial x-, y-position and orientation, theta, of the vehicle.

  • Interpreted execution — Simulate model using the MATLAB® interpreter. For more information, see Interpreted Execution vs. Code Generation (Simulink).

  • Code generation — Simulate model using generated C code. The first time you run a simulation, Simulink generates C code for the block. The C code is reused for subsequent simulations, as long as the model does not change.

Tunable: No

References

[1] Lynch, Kevin M., and Frank C. Park. Modern Robotics: Mechanics, Planning, and Control 1st ed. Cambridge, MA: Cambridge University Press, 2017.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced in R2019b

See Also

Blocks

Classes

Topics