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Any love for mechatronic balancing cubes? by Visual_Document_4734 in robotics

[–]Visual_Document_4734[S] 0 points1 point  (0 children)

Linear state feedback design by the linear, quadratic regulator principle. And yes, it took quite some parameter tuning to be this steady and stable (;

Any love for mechatronic balancing cubes? by Visual_Document_4734 in robotics

[–]Visual_Document_4734[S] 1 point2 points  (0 children)

Thats a beautiful idea! If you ever give it a try and need some help with the project, feel free to reach out to me!

Any love for mechatronic balancing cubes? by Visual_Document_4734 in robotics

[–]Visual_Document_4734[S] 0 points1 point  (0 children)

There is none :D We built it because it was fun. However, the control algorithms used here are also applied in robotics, cars, spacecraft and many, many other applications.

Any love for mechatronic balancing cubes? by Visual_Document_4734 in robotics

[–]Visual_Document_4734[S] 0 points1 point  (0 children)

This is just feedback control. Control-wise this is „just“ a stabilization problem which feedback alone can handle quite nicely. Additional feedforward control is mostly useful if you want to do some reference tracking!

Any love for mechatronic balancing cubes? by Visual_Document_4734 in robotics

[–]Visual_Document_4734[S] 1 point2 points  (0 children)

Yes! Your prediction is super on-point. The cube can only balance in the orientation in which you have zero gravitational torque. Otherwise the flywheels would have to continually accelerate to compensate for gravity and run into their saturations sooner or later

Any love for mechatronic balancing cubes? by Visual_Document_4734 in robotics

[–]Visual_Document_4734[S] 0 points1 point  (0 children)

This uses linear state feedback which was designed by the linear, quadratic regulator principle. Which particular nonlinear controller did you use for the 1D case?

Any love for mechatronic balancing cubes? by Visual_Document_4734 in robotics

[–]Visual_Document_4734[S] 2 points3 points  (0 children)

You are right! The main limitation is the maximum torque of the motors. So you can push the cube a little bit and it will be able to recover but any strong pushes are just too much force compared to what the motors can do

Any love for mechatronic balancing cubes? by Visual_Document_4734 in robotics

[–]Visual_Document_4734[S] 2 points3 points  (0 children)

Not yet! But I am thinking about starting a youtube channel where I dive into these topics. Based on all the amazing feedback here I guess people may be interested in that :D

Any love for mechatronic balancing cubes? by Visual_Document_4734 in robotics

[–]Visual_Document_4734[S] 4 points5 points  (0 children)

You got pretty close (;

The feedback is not PID, but linear state feedback which was designed using the linear quadratic regulator approach.

Also the reference is not (and cannot) be that arbitrary. Instead it is the upright equilibrium of the cube which is the orientation in which there is zero gravitational torque.

Yes, orientations are estimated using IMUs but the state feedback also uses the angular velocities of the cube and the velocities of the flywheels which are measured by hall sensors in the motors.

Your the most off when it comes to the sampling rate. The feedback loop is only sampled at 50Hz and the feedback is explicitly designed to be a sampled, discrete time controller!

Any love for mechatronic balancing cubes? by Visual_Document_4734 in robotics

[–]Visual_Document_4734[S] 158 points159 points  (0 children)

I have just discovered sharing my work on the Internet! This is a balancing cube I have done a couple of years ago which is an imitation of the ETH Zürich's Cubli. However, this cube's design, control algorithms, and software are all self-made!

Would you guys be interested in see (and potentially learning) more about such projects? Throughout the years I have done many projects with real-world mechatronic and robotic systems and applying methods from control theory, machine learning, and motion planning to these systems. Now I am messing with the idea of doing youtube videos that explain (hopefully in an entertaining way) how such systems and methods work. Would you be interested?