Double Inverted Furuta Pendulum

This is a video of my final project on the furuta pendulum made at NTNU(Norwegian University of Science and Technology). The system is made at the university and uses RTW generated code that runs on a QNX computer. For sving-up it uses feedback linearization and a controller that pumps energy into the system. The balancing controller is derived from LQG. Since the system uses full-state feedback and only the angles are measured, the angular velocitys are estimated by measuring the time between two angular positions. This in combination with flexibility in the aluminium rods, delay in the acquisition and control system and choice of controller results in oscillation.

Category:

Science & Technology

Tags:

• Double
• Inverted
• Furuta
• Pendulum

[TheBeefBaron]

HOORAY SCIENCE! But seriously, what software did you use to model and control that? It's very neat.

[oyvindbjo]

@TheBeefBaron Matlab is used to implement the controller algorithm, and to generate RTW code to run on a target computer. The modeling is done with euler parameters(by hand if you want), but that's a whole other masters degree.

[TheBeefBaron]

@oyvindbjo Nah the math is the easy part! Did you use the transfer functions in MATLAB, or did you use simulink? And the RTW code you mention, is that creating a C code that you run on a microcontroller or do you have a separate computer and are using the 9-pin DIN connections as input and output signals? Did you specify the inputs and outputs you were connecting to in MATLAB or did you have to modify the code it output? Sorry for all the questions I'm sure you're busy with school.

[oyvindbjo]

@TheBeefBaron Simulink is used, but since the system is nonlinear almost all math are implemented in S-functions. The system is controlled by a target pc that runs the real-time operating system QNX, with a custom device driver to interface an IO card. Code that runs on the target pc is generated by RTW wich gives you c-code. To link the RTW c-code with the QNX device drivers you need to make S-functions in Simulink. In a way you modify the c-code but you do it through S-functions....

[ssyreeni]

Holy shit! I thought both double-pendulum and Furuta were hard enough by themselves...

How high up does the control law actually go in this case? Intuition says in steady state, it has to be something like fourth order or above. And what's the amount of feedback?

I don't even want to guess how you get it to self-erect...

[oyvindbjo]

@ssyreeni There are several controllers: swing-up controller of the first rod, then a balancing controller of the first rod. These two controllers doesn't care about the second rod, it's just noise, so a four state controller is used. For the swing up of the second rod and balancing of the whole system six state controllers are used

The system uses a 1.5KW motor, so quite dangerous......

[RicardoATBarbosa]

This is serious stuff man! Congrats!

[funkboxing]

Very very cool!



[TheBeefBaron]

@oyvindbjo Cool thanks I might try playing with something like this. I could use a refresh on some controls work.

[relentlessaddict98jm]

@andresdelvado sooooooo many uses from programmes like this u can make self stabilising .....anythings heheh

[nlReWout]

That is pretty damn impressive!!!