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Simple 2D kinematic vehicle steering model and animation

version 1.2 (2.89 MB) by

This is a simple 2D kinematic vehicle's steering motion and visualization in Simulink.

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This is the Readme file for a simple 2D kinematic vehicle's steering motion and visualzation implemented in Matlab's Simulink. There are no special libraries or additional toolboxes required.
This Simulink model solves for the fixed terrain frame's XY position of the simple kinematic vehicle motion and visualizes the result using Matlab graphics. The Simulink model's base simulation timestep is h_fixed=0.05(s), or 50ms. On a 2Ghz Dell Inspiron laptop this model achieves near real-time operation at animation frame rates of 20fps to 30fps.

The Ackermann steering relationship delta_Ack = L / R is an approximation for a vehicle of wheelbase length L and track width W turning without slipping on a constant radius circle at low speed.

The Ackermann relationships are presented in Gillespie's 1992 text on page 186, Milliken and Milliken's 1995 text on page 128, or Wong's 2008 text page. 364. However none of these text's adequately and succinctly summarize the body-fixed velocity transformed into inertial, or terrain-fixed SAE XY coordinates. The handwritten notes provided here summarize the complete kinematic equation development.

Software Versions Tested:
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This model was developed and tested using Matlab R2014 and R2015 and should work with most other versions. The animation s-function is a modified version of the level 1 m-file s-function from the Mathworks example provided in sanim.m.

Writing .jpeg animation frames to disk at each animation interval slows the simulation considerably. Set animation frames per second, anim_fps, in setup.m and re-run setup.m. Don't forget to turn off your file synchronization services to avoid syncing all the new image files.

Getting started:
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Get started by unzipping the .zip file, changing directories to the folder, then running setup.m
at the Matlb command prompt. This will clear the workspace then populate it with the necessary variables to run the Simulink model and associated animation. It will also open the Simulink model file. Press Play or Simulation | Run to execute the Simulink model. The light blue s-function block will bring up the 2D animation figure window and display the steering vehicle at anim_fps frames per second.

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Distribution file list:
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[00_Readme.mdc.txt] - this file

[setup.m] - run this first, it will bring up the Simulink, then press play to simulate the vehicle

[createAviMovieFromAnimationSequence.m] - auxiliary m-file script for converting a sequence of .jpg images into an Avi using Matlab's VideoWriter() function.

[graphical_development.m] - auxiliary m-file script useful for developing the s-function graphics

[sanim_XY_vehicle_viz.m] - Simulink m-file s-function that displays Matlab graphics objects each animation interval (set by anim_fps in setup.m) to create the animation.

[veh_object2.m] - supporting m-file function to create vertices and faces for vehicle and tire graphics objects

[vehicle_animation_sim.jpg] - desktop screenshot showing the Simulink model and animation window

[vehicle_animation_sim.pdf] - printout of the Simulink block diagram in case you cannot open the Simulink

[vehicle_animation_sim.slx] - Matlab/Simulink R2015b model that expressed non-holonomically constrained (rolling) CG velocities and solves for vehicle position as a function of time.

[.\anim_sequences] - folder where animation frame sequence .jpg files are stored; change this in sanim_XY_vehicle_viz.m

[.\Documentation\Compere_handwritten_notes_2D_Patch_Vehicle_and_Tire_Objects_Dec_2015.pdf] - example struture for defining Matlab handle graphics patch object faces and vertices, see veh_object2.m for implementation

[.\Documentation\Compere_handwritten_notes_kinematic_2D_vehicle_steering_model_Dec_2015.pdf] - Compere's handwritten notes with equations suitable for determining position of a steered vehicle in the terrain-fixed XY frame.

[.\Documentation\Lecture_01_A Simple 2D Kinematic Steering Model.pdf] - brief description of the model and interesting results with animation traces from points 'o' and 'g'.

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Texxtbook references:
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(1) Thomas Gillespie, Fundamentals of Vehicle Dynamics, SAE, 1992
(2) Milliken and Milliken, Race Car Vehicle Dynamics, SAE, 2005
(3) J. Y. Wong, Theory of Ground Vehicles, 4th Ed., Wiley, 2008

-----------------------------------
Marc Compere, comperem@gmail.com
created : 11 Jan 2016
modified: 17 Jan 2016
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Comments and Ratings (11)

HYUNJUN PARK

sercan

sercan (view profile)

Marc Compere

The reference is the Society of Automotive Engineers (SAE) J670e standard which defines a right handed coordinate system with +Z-down. This is standard practice although the Z-up is also used. Both are referenced in your link for comparison.

This animation software conforms to SAE J670e Z-down coordinates. Notice carefully which was positive Y is pointing.

Tommes

Tommes (view profile)

Thank you for sharing this model.

What is your reference for the fixed coordinates? According to B. T. Fijalkowski "Automotive Mechatronics: Operational and Practical Issues, Band 1", p. 211 you should switch your X and Y axes.

Compare also:
http://hosting.umons.ac.be/html/mecara/grasmech/standardterminologyforvehicledynamicssimulation.pdf

Thank you so much for sharing this! I was looking for the exact same thing. Thank you

little jhon, you probably have older version of Matlab than 2014 or 2015.
Change 'animation sequence name' in blue box for sprintf('myStr') and everything should be fine then.
Hope it will help.
Have a nice day.

little jhon

When i tried this model ,matlab just remind me that the datetime is undefined , it's very kind of you to help me solve this problem.
Have a goodday, thank you.

The matlab is crashing on a attempt to run the mdl file.It would be nice if you can help me with this issue

Updates

1.2

- minor text change to steering input - units are (rad) not (rad/s)
- bug fixes and improved console output in createAviMovieFromAnimationSequence.m

1.1

added thumbnail on Matlab File Exchange, no code changes

1.1

continued attempts to make the .gif preview work

1.1

minor zipfile update to show the .jpg preview in Matlab File Exchange. Also, changed to R2014b version of the .mdl file.

1.1

minor .zip file improvement to add the file and animation screenshot

1.0

minor .zipfile update

MATLAB Release
MATLAB 8.4 (R2014b)

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