ELECINF344/381

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

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Ball-E’s new PSSCs

Through yesterday’s presentation and teachers’ comments, we have defined our new Project Specific Success Criteria.

Here they are :

Work Manager Deadline
Kalman filter working Otilia 04/24/2012
Complementary filter working Pierre-Hugues 04/24/2012
ADC to measure battery level working Scott 04/28/2012
Zigbee working Otilia 04/28/2012
Wi-fi working Matthieu 04/24/2012
H bridges Pierre-Hugues 04/23/2012
Motors’ piloting Pierre-Hugues 04/24/2012
Fixing PCB/IMU/Batteries Matthieu 04/25/2012
Cooling circuit Mattthieu 04/25/2012
Ball-E is standing Scott 04/27/2012
Ball-E moves the way we want Scott 05/02/2012
We can pilot Ball-E with an Android smartphone Matthieu 05/04/2012

Yesterday, I also managed to make the leds blink on our Ball-E board, let’s begin the Wi-fi !

Matthieu Tardivon

USB charger finished (hopefully)

Today Helen and me finished the schematics for the USB charger for the battery. We used the LTC4088 chip. This chip has a good current load capability and also can drive an external transistor to allow the power to be drawn directly from the battery. Hopefully this is the final design. We hope to do the routing over the weekend now.

Gabriel Teixeira

USB charger plus power source done and undone

Most of the last week, including the weekend I spent searching for an architecture for the USB charger + a buck-boost converter for the board components, which would require a source for 3.3V and 5V, plus another separate regulator of 3V exclusively for the motor.

The USB charger schematics was mostly done by this Sunday (only the schematics of the CI was missing in the library, thus I left it to place in a second time) until we meet with the professor Monday. We found some downsides:

  • The battery would provide from 2.75V to 4.2V, thus the buck-boost CI that I chose could not provide the right regulation at 3.3V (since the CI could do buck or boost, but not both at same time).
  • There was an issue for using the robot while recharging.
  • The motor had to be changed to another one that needs 9V of input.
  • The components that required 5V were removed.
So all the time spent making the schematics was written-off. At least I could study how to build a (more or less) proper USB charger. Now I hope that the new power source architecture is ready and can be written on stone, or I risk to increase even more the time of the development.

Gabriel Teixeira

Articles about batteries

Today, me and Félix finished the article about batteries. The resulting article is published using Google Docs in this link for all the internet (potentially for our shame…) and is open for comments from everybody. Now I think that without any other tasks to do, I will be able to focus only on the project.

Gabriel Teixeira

Rose Ace : My computer is running at 1000rpm

Today we make an experiment with the Gumstix. Our problem was to know if in turning at 1000rpm in a ventilator the WiFi will work correctly.

The first was to get a wireless power source to the Gumstix.

We got a lot of problems with that. First of all, the power connector of our Tobi expansion board is damaged (thanks to Copterix :o ) which cause a lot of reboot at any movement… We solved this with a lot of gaffer.

Secondly our hacked connector (with sticky tape) for the battery was not very well either and caused some trouble. Thanks to the PACT project which order a lot more than necessary 9V battery connector we improved our power line.

And last problem for the power, our board was rebooting in loop before we had a chance to login in… Simple problem but hard to guess, our battery didn’t deliver enough current. It was easily solved with a second battery in parallel.

Now, add a lot of gaffer to secure into place the batteries, the Gumstix and the antenna and we’re ready.

Of course, Murphy’s law requires, at this exact time the Gumstix decide to no longer properly boot and the WiFi to stop working. But with a little of black magic that finally worked and we have done our tests.

 

Our ventilator was missing of power and can’t get to its maximum speed (~1100rpm) with our board mounted on it (we could do better with a better balancing of the weight). But at the speed that we reach we succeed to had no loss of bandwidth (to confirm with a faster ventilator) which is a good news.

The bad news is that even placed on a table at 20cm from the computer we can’t do better than 1.5MB/s of transfer rate in WiFi (and 3MB/s in ethernet…) which is some kind of disappointing.

Félix