Kalman or not Kalman?


I haven’t posted updates in a while, we had one week of vacation to work on our project. Some things have already been explained in other post so here is a little summary.

We achieve to open the unbreakable shell of a sphero and look what’s inside. We then tried to guess which components are used for each functions: micro processor, accelerometer/gyrometer, magnetometer and so on.

The pcb is easily separated from the mechanical base (unless you unwillingly strip a screw and try everything in the world to get it out without destroying the board)

Be careful when you unscrew things..

Be careful when you unscrew things..








A good surprise was that the mpu used is exactly the same we worked with in class: the STM32F103CBT6, what a relief!
We want to reuse sphero’s base with our own pcb so we have to decide wich functions we want to use that sphero can do. Here is what’s we found on sphero that we might use:

  • The induction charger with 2 li ion cells, and the device to manage the charging.
  • The IMU (Inertial Measurement Unit) uses an accelerometer/gyrometer (3 axis each), we believe it’s the same that in the Galaxy s3!
  • A 3 axis magnetometer, apparently it’s there but we couldn’t identify the part. After investigation we found that orbotix decided not to use it because of the magnetic noise procuded by the motors  link here.
  • The bluetooth chip.
  • External cristal oscillator for the mpu.
  • The mpu: a STM32F103CBT6
A nice piece of work!

A nice piece of work!


Now our problem is to choose whether or not reuse the same parts for the same functionalities. Why bother to search for something else if the part they use does it’s job well?

Stay tuned to a further update on how we will choose the components.20130311_132352








Almost Ready for the communication Challenge

Since Monday I spent a lot of time working with the stm32 board and making little achievements step by step. I finally achieved to make all the different parts work: LCD, button interrupts, rgb leds, xbee, using threads with mutexes and making the buzzer ring.  There is one little last step I need to do and will finish this afternoon: make the buzzer ring at the frequency received via xbee.

Since I worked a lot for this part of the class I didn’t have much time to think and talk about the Rose Rolls project with the team.  There is a huge modification in our objectives because we acquired 2 spheros to play with. Instructors suggested that we can hack them for our project instead of building a complex mechanical system for a Spheric Robot.  Because these balls are tiny we withdrawn the idea of putting a camera on it. However one new axis of reflexion is to explore the communication between 2 spheros and I am really liking this idea. We still need to clarify those points together and make sure that everyone agrees with that. We already lost some time changing the subject but it’s better now than later when it’s too late.

See ya.

Blinking Led

Here is my update for the past 3 or 4 days:

This week end I didn’t have much time to work on the tp so I just made some comments and thought about the specifications of Rose Rolls. We prepared the presentation a bit late but we achieve to write down some clear ideas and goals.

During the presentation, our teacher pointed out a idea we didn’t have: Instead of having difficulties and making some complex mechanics, we can simply hack a sphero and enhance its capabilities.

This evening I worked on the stm_32 project and I achieved to make the led blink and control the color  rgb style. I’m now working on controlling the lcd screen and I hope to finish that tonight.

LCD presentations

Today I did some work on the presentation of LCD modules with Hubert, we spent some time trying to figure out how the small ram inside is mapped onto the screen. The main part of the presentation is done, we still need to do some enhancements.

First proposition of features and PSSC

This afternoon I wrote my first ideas and propositions of features that I want to see on the robot and shared them with my team so that we can have something to start with.

Here are some of the features we discussed:

  • Rotation in pitch and roll
  • Transparent casing
  • Wi-fi or Bluetooth remote control (for control via a smartphone)
  • Embedded Camera
  • Video streaming
  • Obstacle avoidance
  • Line following, can be used to navigate inside a building
  • Following a moving known object
  • Following someone (leg tracking??)


presentation and lego

Today we were assigned a presentation, mine is about lcd screens for embedded  systems. I started gathering informations and tried to understand what signals are in the connector for 4b/8b modes.

We agreed with my partner to search on our own tonight and merge our informations tomorrow. I’m starting to write down what I have found.

We found a name for the robotic sphere project: Rose Rolls (or Rolls Rose). We made some drawings of a system wich uses one wheel in contact with the inside of the sphere to make it roll, as on the picture.

Drawing brain-storm

Tonight we gather to make some prototypes for a system with a weight made from legos.


Robotic Sphere

Today began by everyone choosing their subject,

I chose the robotic sphere project because I find that a moving device is really fun to design and to watch when finished.Today’s work was mainly trying to subscribe to all the different websites and messing up with the passwords.

We discussed about some of the features that we could implement in the robot:

  • Obstacle avoidance
  • Autonomous navigation
  • Remote control by a smartphone
  • Video streaming

We started a shared document to discuss about technical specifications but there isn’t much yet.

The project members are: Quentin Michelet, Clémentine Barbet, Charles Thin and me.