multiple wireless accelerometers for data acquisition

Hi there

For my final year project i am doing research into mass movement of motorcycles under suspension movement. To do so i need to use up to five accelerometers to measure the acceleration of the masses, to then find force and through integration to find velocity and position. In an ideal world i wouldn't have wires draped all over the bike so would like to do this wirelessly. However thinking about it, it could get quite complicated for a beginner like me. I am currently testing with simple masses on springs so can try out ideas on one or two accelerometers first. Currently i have the following to play with;

Arduino uno R3 x2 (one genuine, one elegoo), elegoo mega and genuine nano

5 mpu 6050's

xbee shield

(Funduino Bluetooth Shield for Arduino UNO Keyes EB-014 Xbee Flux Workshop | eBay)

xbee HC-05 modules x2

(https://www.ebay.co.uk/itm/Keyestudio-Bluetooth-HC-05-XBee-B2-0-Module-KS-143-Master-Slave-Flux-Workshop/112191238981?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649)

an SD card module (Genuine Arduino)

an RTC (Genuine Arduino)

Would it be better for simplicity to use analogue accelerometers as i don't fully understand Jeff Rowbergs
code?

is it possible to connect the accelerometer and the bluetooth module on there own with a power supply?

Would the above setup need an arduino to process the data pre sending over bluetooth?

I saw somewhere that a 9V PP3 is not the best power supply for an arduino? so what is optimum?

Is it possible to connect more than two MPU6050's to one arduino? I've seen that you have to change the I2C addresses but only saw a maximum of two being used with one stock address one 0x69.

is the smallest increment an RTC measures in a second?

can i send multiple sensor data to the same SD card? if i say, connect the SD card to the host arduino and save all the data after it has been sent or do i need to do it at the accelerometer?

So to sum up. Need five accelerometers on a bike, either send all five accelerometers data to the serial monitor or save to the SD card with time in a column next to it.

Thanks

Ross

is it possible to connect the accelerometer and the bluetooth module on there own with a power supply?

Not in any useful way. The bluetooth device transmits serial data. The accelerometer does not output serial data.

is the smallest increment an RTC measures in a second?

Measures? No. Reports? Maybe. Depends on the RTC.

can i send multiple sensor data to the same SD card?

Data is data. Doesn't matter where you got it. Of course you can.

or save to the SD card with time in a column next to it.

Absolute time? Or relative to some event, like the Arduino being reset?

Is it possible to connect more than two MPU6050's to one arduino?

Yes, use the address pins AD0 as "chip enables", with one Arduino output per each AD0. Only the MPU6050 with AD0=0 can be addressed at 0x68.

You don't need to use Jeff Rowberg's code, but if you want this project to succeed, you do need to understand whatever code you use.

Yep, also need to ensure there are no significant 'delays', otherwise one piece of measured data might not link instantaneously to what's actually happening.

Hi there, thank you all for the replies.

@PaulS -

So if bluetooth transmits serial data and the accelerometer doesn't give that, then i would need something like an arduino nano to convert it to serial data before bluetoothing it across to the main board, connected to the computer and SD card?

And to your last question, i need the time in either milli or micro seconds (hence the question about the RTC) from the point the accelerometers are told to start measuring/ data comes in. In Jeff Rowbergs code for example, it says "Send any character to begin DMP programming and demo:". I need to measure from that point. Currently i am just subtracting the first number in the data away from everything else.

@jremington -

Would using multiple accelerometers mean that to print the data to the serial monitor they would have to be called as MPU1, MPU2 etc?

to print the data to the serial monitor they would have to be called as MPU1, MPU2 etc?

The Arduino can collect data from only one sensor at a time.

You can print data from several sensors on one line.

The Arduino can collect data from only one sensor at a time.

You can print data from several sensors on one line.

So if i am running 5 sensors, does the arduino choose when to accept the data and allocate it to the filename corresponding to that sensor? or does it have to be programmed in? Feel free to just send me a list of points to research as i wouldn't know the names of what i would need to be searching. For example "research state machine approach" throws up a lot more results than "button to stop a program"

and also, what is the best power supply to use if not connected to a computer? was thinking of using an accelerometer connected to a nano and a bluetooth module, powered by 2 x 14250's (1/2 AA Li-ion). could that work?

So if i am running 5 sensors, does the arduino choose when to accept the data and allocate it to the filename corresponding to that sensor? or does it have to be programmed in?

Either the Arduino contacts the device to collect a data point, or you can have the device notify the Arduino (at programmable intervals) when a data point is ready to be collected.