Me and my teammates building a pneumobile, this is a compressed air driven "race car". If you interested in this, check out the official site (we won the race three times!).
I need to gather a lot of data to improve our vehicle, so i decided to design a telemetry transmitter, which could be the car's onboard computer too.
First i need to buy some hardware, so please tell me your oppinion about the selected components:
1 Compass Module - HMC6352
2 XBee Pro 50mW Series 2.5 RPSMA
1 5DoF IDG500/ADXL335
1 20 Channel EM-406A SiRF III Receiver with Antenna
1 XBee Explorer Regulated
1 XBee Explorer USB
1 Serial Enabled 20x4 LCD
And i already have an Arduino Mega board.
The plan is that, the arduino communicate with labview, which displays and stores the data, and a LCD display some information to the driver also.
I done some smaller projects with arduino before, also i have experience with electronics and labview, however i'm a mechanical engineer student, so this is not my expert area.
I was really digging the site until I read rule 4a (2010):
"The conversion of energy of compressed air to mechanical energy should be performed by pneumatic cylinders and valves of Rexroth."
Seems strange that this is limited to the components of the sponsor? What if you have some amazing new pneumatic motor design you want to use or something?
Then again, "should" seems to leave leeway...is there any?
Interesting project. I am doing something similar (telemetry and drive control for an electric car) so I have done a bit of research into components.
2 XBee Pro 50mW Series 2.5 RPSMA
There are some new ones out now - XBee Pro ZB, which have longer range, are lower power consumption and are cheaper.
You probably want to go with the RP-SMA modules and the modules will then do up to 2 miles with some suitable antennas.
1 Serial Enabled 20x4 LCD
If you have a mega board I would be questioning why you are using one of these. Also, if it's going to be on the car, why you have a display at all/why it needs to be as big as a 20x4. I understand the driver might want to see what is going on but is it necessary? Might it distract the driver from the actual driving of the car.
I presume you are also going to need some kind of battery pack to power it all. Bear in mind that the LCD with backlight draws a lot of power, perhaps you want to go with a transreflective LCD instead of one with a backlight.
cr0sh:
it's ok to use only Rexroth components, they have everything what we need, and they give the components to the teams for free
on the last race there was 5 different motor types, which cover the most efficient solutions
the efficiency is the key, because every team has the same quantity of "fuel"
these cars can go up to 9 kilometers (5.6 mile) with the avarage speed of 12 km/h (7.45 mph), and the max speed is more than 40 km/h (24.84 mph)
i choose XBee Pro 50mW Series 2.5 RPSMA, because i want to buy everything from one place and this what sparkfun have
i need the lcd only on the maximum distance run, where the max speed of the vehicle about 10-15 km/h so it won't distract the driver, i want to display the actual speed, avarage speed, distance and send messages to the driver through it
i picked a serial lcd, because maybe i add later some other control functions to the circuit and don't know there would be enough pins for those
the pneumatic elements uses 24V so there are two 12V 4Ah accumulators already
ecause i want to buy everything from one place and this what sparkfun have
Ahh, I understand.
i want to display the actual speed, avarage speed, distance and send messages to the driver through it
Ok, yeah a 20x4 sounds pretty suitable then.
i picked a serial lcd, because maybe i add later some other control functions to the circuit and don't know there would be enough pins for those
Well I would have thought you probably would but a serial LCD is easy to use too.
Sounds like you have had a good think through about how you are intending on going about this.
the pneumatic elements uses 24V so there are two 12V 4Ah accumulators already
Sounds like there's not too much of an issue with power consumption then.
could you tell me more about your project?
Well, what would you like to know?
Anything specific?
It is a based on an ATmega1280
Xbee Pro ZB wireless modules for telemetry and in-race control of vehicle control variables.
Current sensor for motor drive circuit.
Battery voltage sensing for each 12V battery (2 in car for 24V system)
Sensors for motor temp, air temp etc.
DS3231 RTC for timestamping data being logged to uMMC SD module.
Hall effect sensors for motor speed and car speed.
Automatic motor control based on sensor data (mainly current data, car speed and motor speed)
Automatic gear with a NuVinci CVT hub gear and servo motor.
etc. ;D
Any questions, ask away. The project is in its early stages concerning construction but I'm getting there
wow, we also want to use a NuVinci CVT with a servo motor
how would you like to control the gear changing?
Yeah it's pretty nice. I am thinking of using a standard hobby servo (probably going to need one with 360 deg rotation) but I have not got round to working out how much torque I am going to need yet.
I have the hub gear and it does not seem to require too much in the way of force for gear changing, I will have to see when I get my rig built up what it's like under load though .
and what kind of software you use for displaying the telemetry?
At the moment I am not sure. It will most likely be a simple processing application displaying the data and allowing variables to be changed up/down.
The data collected by the logging module will probably just be analysed as graphs on Excel or similar after the race.
