Interactive web site of Télécom ParisTech's ELECINF344/ELECINF381 Robotics and Embedded Systems classes (a.k.a. ROSE, 2012 session).


Simulations, Presentation, and Understanding ChibiOS

For the past few weeks I have been working hard to understand a mash of Matlab, Simulink, VRealm, Mathematica, and most of all ‘math’ itself; all of this in attempt to fully understand and simulate the 3D modeling and feedback control of the state of the art rezero robot. The information included by the rezero team is impressive, but the matrix translations and binding equations for describing the coupled state of the robot are too complicated to understand and implement in the amount of time remaining.

The BallIP implements a straightforward planar model, in which the movement of the ballbot is described in 3 separate 2D planes (XZ, YZ, and XY). The feedback control loop is modeled as a PD loop. The theoretical values are computed and then tuned for the real system. The first attempts to reproduce the nyquist plots given in the BallIP report were unsuccessful. I can only imagine that its a misunderstanding on my part of the interpretation of transfer functions in matlab. This is something I will have to get help on from one of the TSI professors.

Today I started up on coding in ChibiOS along with the rest of the group by testing a thread which flashes a LED. Pierre-Hugues has set all of the configurations for the BallE board so it was fairly easy to pick up demo code and get it running.

To further understand ChibiOS I will also start playing the usage of the PWM during the vactatio (sooner than later). Hopefully in parallel I have time model the transfer functions used by BallIP.

More to come…

Scott Messner


Possibly related posts:

  1. BallE – mechanics and control review
  2. Batteries presentation and work planning
  3. Initial projects presentation
  4. DCC and Morse code

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