I’m a mech. eng. and I’m developing a project related with Motorsport wish require an hardware assembly that it is at the moment beyond my reach. I’ve a basic knowledge of how each component work but that’s it.
What I’m seeking with this post is to understand what kind of components the hardware require to operated as intended and (if you know) what is the average charge price for a third party to assembly it.
Below a brief description of what’s pretended.
Thanks in advance for the help.
The hardware is divided in 2 parts. One part is to be place inside of a moving vehicle with the purpose of acquire data from sensors and transmit them to the pit-box and the other is connected to a laptop and receive in the transmitted data.
The sensors are four passive RFID readres, one 9 DOF sensor (3 accelerometers, 3 gyroscopes, 3 magnetometers), one GPS receiver and one gasoline/diesel flowmeter.
The main board of the hardware that goes on the vehicle is unknown but must be able to collect all sensors data, package it in a structure and transmitted to via radio.
The antenna is unknown but must have a 5km effective signal range
The radio receiver is unknown but must be able to pick up the signals from the antenna.
The main board that connects the receiver to the laptop is unknown but it must be able to unpackage the data from the sent structure and make it available to programming language software (C++,C#,VB.NET,etc.)
Arduino processor to read sensors and output the data as aync serial to an XBee radio module.
A second XBee module with an XBee to USB adapter that plugs into the Laptop’s USB port.
You may neeed the XBee Pro modules that have a higher output power for more range.
The radio link is setup as a transparent aync serial link. What goes into the remote XBee comes out of the XBee to the Laptop (see the wireless/RF forum for more).
The Arduino is fairly easy to write code for since there is a huge user base and good free programming tools (see the Arduino forum here for more).
You can use any programming language on the laptop that you are comfortable with.
My 1st question is whether your want to roll-your-own telemetry system or buy one ? They certainly exist as off the shelf items (big $$s) buy making one will take some time and effort. Second question is data rates on the given signals, how often is each to be sampled ? How accurate must each sample be and (related) what kind of resolution is desired ? This and sample rate(s) are key parameters to design your tele system.
I’m trying to build my own telemetry and I have the time and motivation to do it.
As for data specs I’m thinking between the range of 1~10 Hz as sample rate, 10^-3~10^-5 as resolution and an accuracy of 0.1~0.01% but the values can change in the second prototype depending on data quality vs. investment.
Silveira:
As for data specs I’m thinking between the range of 1~10 Hz as sample rate, 10^-3~10^-5 as resolution and an accuracy of 0.1~0.01% but the values can change in the second prototype depending on data quality vs. investment.
I don't know that you'll get 1 part in 100,000 resolution, that would be 17 bits and I doubt any of the hobby level devices support that resolution or accuracy. Look at the MPU-9150 sensor.
It claims 16 bit resolution on the 3 axis accelerometer and 3 axis gyro but only 13 bits on the magnetometer. Error due non-linearity is spec’ed at 0.5% and 0.2% respectively. I don’t think any of the other common parts are much better.
Doing a rough calculation, (4 RFID + 9 DOF + 1 Flowmeter + (1+1) GPS) * 64 bits (if not 32 or 16) = 1024 bits = 1 kb
1 kb * 10 Hz = 10kbps
Yes, 1 byte is 8 bits but for async serial there are the additional Start and Stop bits for a total of 10 bits per byte sent. There could be 2 Stop bits which make 11 bits per byte but this is not that common.
As for data specs I’m thinking between the range of 1~10 Hz as sample rate, 10^-3~10^-5 as resolution and an accuracy of 0.1~0.01% but the values can change in the second prototype depending on data quality vs. investment.
I don't know that you'll get 1 part in 100,000 resolution, that would be 17 bits and I doubt any of the hobby level devices support that resolution or accuracy. Look at the MPU-9150 sensor.
It claims 16 bit resolution on the 3 axis accelerometer and 3 axis gyro but only 13 bits on the magnetometer. Error due non-linearity is spec’ed at 0.5% and 0.2% respectively. I don’t think any of the other common parts are much better.
Thanks for the info.
I’m prefer to push a bit the specs in the prototype rather than have a under-spec equipment from the start. The 9 DOF doesn’t strictly need to be 1 IMU. it can also be a 3+3+3 DOF.
I am a bit lost about Adruino and the component that bridge the receiver with the pc. Any help please?
@OP - You might want to post in the wireless forum and ask what kind of transmitter/receiver pair would work for a 5 km distance, car to basestation, at perhaps 30kbps. I’m thinking you may need FCC licensing.
@OP - You might want to post in the wireless forum and ask what kind of transmitter/receiver pair would work for a 5 km distance, car to basestation, at perhaps 30kbps. I'm thinking you may need FCC licensing.
How about something like XTend or XStream ([http://www.digi.com/products/wireless-w ... f-modules/](http://www.digi.com/products/wireless-wired-embedded-solutions/zigbee-rf-modules/)) or XBee Pro 900HP ([http://www.digi.com/products/wireless-w ... 00hp#specs](http://www.digi.com/products/wireless-wired-embedded-solutions/zigbee-rf-modules/point-multipoint-rfmodules/xbee-pro-900hp#specs))?
And I’m worried about places like Laguna Seca where’s > 160’ of elevation change. There’s track which isn’t visible from the pits or any place you’d put your receiver. More over you can’t go to any track like LS and blast whatever RF you want to. They’ll have some management plan you’ll have to conform to. That’s something to look into.
For those reasons and more one of the crowd sourced tele projects used cell phone tech to upload the data. If the bit rate can be kept reasonable, that may be a way to go.