All posts by Christian

Distributed Micocontroller System

The idea of distributed mcu’s

After finishing with the TUG Racing Team i wanted to try something different. My friend and I had the Idea to do some lightning and temperature measurements in our rooms or only switching on/off any device. Sure with an embedded microcontroller system its possible to switch and measure everything, assuming you have your hardware well designed.

But, if you are using microcontrollers you’ll often use some low layered interfaces to communicate with your device: e.g. you will have some buttons or an rs232 interface with a terminal on your pc.

Maybe you can go a step further and use TCP/IP communication but you will need an UI on your PC/Smartphone you are using. So thats the main point i was struggling the last years. The User changes his device for communication with the microcontroller system several times a day, using different Operating Systems.

Imagine you have a already proven Interface you can use for communication. With HTML and http its possible to use a Interface everyone is familiar, your Browser.

The Idea behind Distributed Microcontroller Systems (DMS)  is to have one microcontroller system, lets call it base station, in your home network, and several low power subsystems connecting wireless with a low cost RF Module to the base station. If you have a end device with the capability of having a browser you’re all in. The Idea is to have control over every subsystem only by connecting your browser to the main station. The low power Subsystems will be designed to operate in extremly low power mode so that battery or powering with a solarpanel is possible.

I’ll try to provide some more details or a block diagramm to show further details.

TUG Racing Team

X-by-Wire 2012 – fully functional

Sure, it was about time to finish the X-by-Wire Box, but due to hard stress this term it was not possible to do it earlier.

Anyway the X-by-Wire Box is although this year again the first standalone selfmade unit, which is fully functional and prepared to be build into our car. I hope we get all remaining important features fixed for the first tests next week.

on the Testbench

As it can be seen on this photo the necessary feature addon Board is already in use!

TUG Racing Team

X-by-Wire 2012 – Feature Addon Board

Feature_Addon_Board_2
Feature Addon Board with X-by-Wire Mother Board

Today i’ve tested the new really tiny (20x41mm) Feature Addon Board V1.0  for the X-by-Wire Box 2012.

The requried Brake Panic Switch is now implemented this way, when the adjusted brake pressure is reached the car shuts down the power to the motors. The system can only be reset by the driver.

TUG Racing Team

X-by-Wire 2012 – Another feature required

I’m really afraid of what some Formula Student Event Organizers think what we are doing but on 3rd of May there was a new rule in the reglement for FS Hungary was published. In order to get all systems working as soon as possible its really hard to understand how a new rule is developed so late this season…

But here is the rule in more detail:

B7.5 Brake Panic Switch
B7.5.1 All electric vehicles must be equipped with a brake panic switch such
that in the event of a panic braking incident, the brake panic switch will
be activated and will turn off the traction system or any drive by wire
actuators.
B7.5.2 The switch must be connected to the brake circuit such that it is
triggered at a pressure which is high enough to lock the wheels in dry
conditions.
B7.5.3 The switch must be implemented with analogue components and not
through recourse to programmable logic controllers, engine control units,
or similar functioning digital controllers.
B7.5.4 This system must latch until manually reset. This may be reset by the
driver in the driver’s cell.
B7.5.5 The performance of the switch will be tested during the brake test.

There are several points i have to criticise.

  1. The main point is, that such a panic switch has to be implemented only with non programmable logic. I do not understand that requirement, because if the pedal box is not functioning properly there will be other problems but surely not only by evaluating the brake preassure, aside from the short circuit and broken wire detection for each brake pressure sensor and additional plausibility checks.
  2. If the performance of the switch will be tested at the brake test, the X-by-Wire Box has to function properly, otherwise the car won’t accelerate anyway.

So the next days will be busy to design the schematic and the board for the required feature. Fortunately there is some free space in the X-by-Wire box, where the new, i’ll call it “Feature Addon Board”, can be placed.

Recent Work, TUG Racing Team

X-by-Wire V1.0/2012 – assembled

I’m glad to say, that after a few tests nearly the whole hardware on the new board ist fully functional now. The housing with the mounted connectors is also ready now to be put into the car.

A few Softwareupdates should also fit the X-by-Wire System to the Formula Student Electric Rules for 2012.

I expected to finish the whole board weeks ago, but i was busy with several other Projects. For example our Battery Management System – and the Powertrain testbench needed a lot of help, because due to some unecpected issues the installation and build-up was delayed by weeks… However it’s really exciting to see how all Systems in our car are getting more and more functional. Maybe i’ll post some pictures of our High Voltage Containment when it’s build up and give a few explanations how the Battery Management System (short: BMS) works in our car.