Electric kart telemetry system

I want to measure some variables related to the behavior of an electric go-kart in order to make an analysis of these data in an application as fast as possible. To do this I need to make a wireless connection between the components installed in the kart and a central where the application will be running receiving data from the sensors. I have read in some forums and websites that the LoRa connection (which can be implemented with a MKRWAN 1310) can be useful to reduce the consumption of the batteries that feed the sensors and the board, and also helps to have a longer communication range. I would like to know what things I should consider when carrying out this project: number of boards, batteries to power the circuit, latency, connection of the components in the kart, ways to protect the components, etc.

Below is a list of the sensors I would like to include:

  • mlx90614 (brake temp)
  • DHT11/22 (ambient information)
  • hall effect sensor (RPM)
  • potentiometers (pedals and steering wheel position)
  • accelerometer MPU6050 (G-force)

I know it's a pretty ambitious project but I'm willing to read recommendations and do my best to make it happen.

1 Like

For a basic telemetry system, transmitting sensor data to a monitoring location close by, I doubt you need to worry about radio power consumption, networking or the extended range offered by LoRa.

By far the simplest and easiest approach is to use something like an Arduino Uno or Pro Mini (which could easily handle all the tasks you outlined), a wireless serial adapter and Serial.print() to send the sensor data to a PC running a terminal logging program. I use TeraTerm and PuTTY for the latter.

Even the cheap, low power HC-12, with >100m range, might be fine for such a task.

2 Likes

If you need multiple samples per second then LoRa is going to be too slow.

Have a look at an "on air time" calculator such as this

Even with a small packet size and the fastest possible settings sending a message takes tens of milliseconds, and the government imposed regulations require you to leave a big time gap before sending the next message so that you don't monopolize the frequency spectrum.

1 Like

At the fastest LoRa setting for UHF, a 24 byte packet will take 5mS to send.

For 2.4Ghz LoRa a 24 byte packet can be sent in 1.6mS in LoRa mode and 0.2mS in FLRC mode.

The LoRa device in a MKRWAN1310 can send a 24 byte packet in 7.4mS in LoRa mode and packets at 250Kbits\sec when used in FSK mode.

1 Like

I like you already.

1 Like

Will the go-kart run in a scaled down circuit?

1 Like

Do you know of any other suitable way of communication (low latency, coverage of no more than 200m)?

It will not be a scaled down circuit, more like a parking lot. It will probably only need a coverage of no more than 200m.

Ok, maybe it's not what I mean, perhaps designated area?

Around 150 square meters

The power consumption of whatever device you build will be trivial compared to the power consumption of the motors driving the go-kart, so I see no reason to be concerned about it. Even if your power supply for your monitoring device comes from separate batteries, given the environment they are operating in recharging at the same time as charging the kart wouldn't be a problem.

2 Likes

WiFi could be an option. Setup is more difficult than LoRa, hardware speaking. Get an old AP (Access Point), place it in the middle of the track and see if the kart can be connected the whole time.

1 Like

Perhaps ExpressLRS.
Essentially a frequency hopping version of LoRa that allows for high packet rates.
Requires SX127x hardware.

or if that is too complicated buy a ready-made transmitter and receiver with an i-bus interface and use that instead of talking directly to the RF chips..

This firmware might be a solution for your needs.

I'm guessing that ExpressLRS is similar to recently announced LR-FHSS system for LoRaWAN.
Frequency hopping and spread spectrum radio systems have been used for 2.4GHz high update rate real-time radio control systems for years

1 Like

I took a look at it and it looks like a great alternative. But I'm just starting out in this electronics thing and it seems a bit complicated to implement. Is it possible to make a simpler communication through an amplified nRF24L01 pair module keeping a fast transmission in the range of less than 150m?

The simplest and easiest to use setup that will work over that distance was described in post #2.

You cannot accurately control the transmission range, as it depends heavily on the environment, the input power to the transmitter, the antennas used and their relative orientation, etc.

1 Like

Simpler, yes. However whilst an 'amplified' setup might be needed to provide the range, increasing power levels might not be legal, you need to check regulations for your part of the World.

Simple setup point to point LoRa would be much longer range than the RF24, so power levels would likely be legal, and should provide the range you want. At UHF LoRa would be capable of circa 60kbits\sec and at 2.4Ghz around 100kbps.

1 Like
  1. What latency in ms could this system have if the kart is kept at a distance of less than 100m from the receiver?
  2. Any wireless serial adapter modules you recommend?

'Latency' would depend on the length of the packet sent and the rate at which its sent, plus a small delay as the receiver software processes it.

If you want 'low' latency send short packets at high data rates.

Most of the data modules mentioned are low cost, so rather that guess which system would give you the range you want, at the data rate you want, buy some modules and do some real World tests.

2 Likes

The one in post #2.

1 Like

This topic was automatically closed 180 days after the last reply. New replies are no longer allowed.