Doubts in building a wireless accelerometer

Other Hardware Sensors
1

Hello everyone,

This is my first query in the forum. I am trying to build a wireless accelerometer to record vibration data. My requirements are

  • small size
  • wifi based data transmission
  • a 6 DOF IMU
  • a rechargeable battery (ex. Li-Po)
  • Maximum sampling/ data acquisition rate (in the range of 300-500 Hz)

I was looking for a microcontroller for the above and found nano boards with inbuilt wifi and accelerometer modules. Before procuring the items I need an expert's advice. Following are my two options:

  1. Arduino nano RP2040: This board has wifi and accelerometer in it but lacks a battery charging circuit. Is it possible to attach an external battery (which can run it over wifi for 1-2 hrs) with a charging circuit to it? If yes then what all do I need ??

  2. Arduino MKR wifi 1010 + Grove-6-Axis Accelerometer with Gyroscope: My second option is MKR1010 which has inbuilt wifi and a battery charging module in which it says I can attach a 3.7 v Li-Po 1800 mAh battery. But it doesn't have an inbuilt accelerometer. In that case, I am thinking of attaching an accelerometer module to it. I am not very sure will it work? Will the data sampling will be the same as in the first case?
    Kindly help with your expertise.

Regards,
Prateek

2

I would personally use option number two, as you would not have to mess with battery charging circuits. Do you know if it has a battery cut off when the voltage gets too low?

3

You don't need a 6DOF IMU to measure acceleration (vibration) data, any accelerometer module will work.

My choice would be an ESP32 module with built in WiFi, connected directly to an accelerometer module using the I2C bus.

4

Thanks, micahfriesen for responding. I was unaware of the battery cutoff. I guess it also gets activated in case you connect the board with a laptop. A power cutoff during measurements would be a definite bummer. Could you please suggest be a battery module for the second option? Also, what will be the power consumption of transmitting data over wifi in MKR wifi 1010? Suppose I want to run the experiments for 1 hrs, or 5 hrs. I want to keep the weight of the entire setup to be minimum. So want to optimize the weight with the battery backup.

5

Thanks jremington for replying. Actually, I do need to measure triaxial acceleration with tilt. Is Grove-6-Axis Accelerometer with Gyroscope a correct choice for that? Also, I have some doubts about the sampling frequency (SF) for the analog signals. I read somewhere that the default SF is set at 104 Hz. And some people have mentioned it can be increased with some changes in codes. Is it possible to achieve a sampling frequency of say 300 Hz for all three accelerometers?

6

Can you explain what you mean by this? The gyro measures rate of rotation, not tilt angle.

7

My bad, I had an inclinometer in my mind. As of now, measuring acceleration on the three-axis is fine.

8

The accelerometer can be used as an inclinometer. It is very simple: How_to_Use_a_Three-Axis_Accelerometer_for_Tilt_Sensing-DFRobot

9

Thanks Jremington. Could please list the components which I need?

10

You will need an Arduino, and a 3 axis accelerometer. Just about any will work.

1 Like
11

I don't know what the power consumption for the MKR wifi 1010 is as i have never had one. A simple google search will bring up some tips on how to minimize consumption though. The reason for the battery cutoff is that if a lipo batteries can get ruined if you let them run too dead. If there was a way you could monitor the battery voltage you could make it so that you would have to charge it when it ran too dead. Like I said I am unfamiliar with that particular board, so I don't have a lot of advice on it.

1 Like
12

Thanks, I found this for MKR 1010 " Battery Power

Its USB port can be used to supply power (5V) to the board. It has a Li-Po charging circuit that allows the Arduino MKR WiFi 1010 to run on battery power or an external 5 volt source, charging the Li-Po battery while running on external power. Switching from one source to the other is done automatically."

Does it mean, the battery which I will be using should be 5 volts? I checked the pins, and it has 3.3v and 5 v as well.

13

Thanks, jremington for answering :slight_smile:

14

No, it is intended for LiPo cells only, which range from 3.2-4.2 V depending on state of charge.

15

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