Hexapod Robot Simulator

A simulator for hexapod pose and gait control based on forward and inverse kinematics.

Dimension	Forward Kinematics

Inverse Kinematics	Walking Gait

This project is implemented by Python with numpy for some matrix computations, scipy.transforms for 3D transformation, dash for user interface and interactive visualization, matplotlib for visualization/animation.

Tutorial

A video tutorial for building this project from scratch is available from my channel on Bilibili (Chinese Language).

How to use

• just run the file ui.py and open on your browser, a web app will be hosted on http://127.0.0.1:8050, .

• in models.py: you can run several visualizations/testings of the single models.

  • Hexapod

    if __name__ == "__main__":
      hexapod = Hexapod()
      fig1, ax1 = hexapod.visualize3d()
      hexapod.solve_ik([0, 6, 2], [0, 0, 0.2])
      print(hexapod.get_legs_pose())
      fig2, ax2 = hexapod.visualize3d()
      plt.show()

    This will print the leg positions (joint angles of each leg) of the hexapod:

    {'MiddleRight': {'coxa': -92.09547174803812, 'femur': 6.36113571972891, 'tibia': -64.60434061668676}, 'FrontRight': {'coxa': -45.09639870158676, 'femur': 0.09531185287904773, 'tibia': -78.66206919332849}, 'FrontLeft': {'coxa': 45.10012726867826, 'femur': -12.077624233788663, 'tibia': -64.00686346144602}, 'MiddleLeft': {'coxa': 88.11133082594907, 'femur': -18.539795381247323, 'tibia': -49.1551576670496}, 'RearLeft': {'coxa': 130.89088550579493, 'femur': -11.540579859453953, 'tibia': -40.477079527074935}, 'RearRight': {'coxa': -139.3256544041924, 'femur': 0.7673781486253016, 'tibia': -44.45742377675202}}

    Two figures of the hexapod's initial pose and the changed pose will also be displayed:

  • Legs

    if __name__ == "__main__":
      leg = Leg(lengths=[2,2,3])
      t = get_transformation_homo([0, 0, 45], [0,4,0])
      leg.change_pose([-60, 45, 30])
      leg.transform(t)
      fig, ax = leg.visualize3d()
      fig, ax = leg.visualizeAxis(fig=fig, ax=ax, scale=1)

    this will display the leg 3D positions and the local axis:

• animation.py: run this file to display animation of the hexapod, followings are examples of tripod gait and IK:

Issues

• The angle range of every joint has not been limited, i.e., it can move from 0 to $2\pi$

• In the inverse kinematics page, the solution may be wrong when it exceeds the allowed tilt range like:

  

  Currently I have yet got an efficient way to address this issue, do you have any good idea?

• Only Tripod gait has been implemented. Other gait will be realized in the Webots project: a simulated hexapod robot with physics engine.

• Functions of some widgets (like the stance sliders in the IK tab) in the UI are not implemented.

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This project is mainly inspired by Mithi's Bare-Minimum Hexapod Robot Simulator

This project is a good example of learn by doing, have fun!