Ttscotchtape
Posts: 12
Joined: Mon Dec 14, 2020 3:20 am

Excavator bucket position

Sat Jun 05, 2021 9:42 pm

Hi all!

I'm realitively new to the Raspberry Pi and Python. I'm working on a project to show me the position of an excavator bucket relative to the excavator base. I'm hoping to achieve this with 4 IMU sensors (one for the bucket, one for the stick, one for the boom, and one on the main frame) and a Raspberry Pi 4 with a touchscreen display. The programming language I'm using is Python. At least 2 of the IMUs (the main frame and boom) will have a magnetometer to show the side to side position of the bucket (the boom can also swing sideways for offset digging).

I know there are forums that touch the subject, but I have spent hours browsing forums and Youtube videos trying to figure out the best way to get real time input from all the sensors at the same time with a reasonable latency. I have been unable to find answers to some of my questions:

-Will the length of the wires effect which method to use? The sensor for the bucket angle will have about 20 feet of wire from the pi to the sensor.
-Which is the best method to accomplish the above? Using a multiplexer? Using GPIO pins to change the address on an MPU6050 or MPU9250 and toggle through them? Using a secondary controller such as the dragonfly development board? CANBUS? Another method I haven't mentioned?
-If latency is an issue with some of the methods, what would be the estimated time frame from one IMU reading to the next?
-Heck, what's the reason the IMUs such as the MPU6050 aren't sold in sets with unique addresses, or are they?
-Can I find detailed documentation to accomplish the suggested method?

Anything that will help me figure out the way forward will be much appreciated.

pidd
Posts: 3945
Joined: Fri May 29, 2020 8:29 pm
Location: Wirral, UK

Re: Excavator bucket position

Sun Jun 06, 2021 2:21 am

I wouldn't have thought latency would be a problem, however with so much metal around I don't think your magnetometer readings will be reliable.

Perhaps you could use optical time-of-flight sensors to measure ram extensions instead of using IMUs but there is probably a risk in dirtier environments.

Limited addressing of devices is annoying but you can run more than one i2c interface, however wire lengths would be problem with i2c.

SPI is good for longer lengths and SPI IMUs are available and as you say you can use other GPIO pins to select devices.

Make sure any cabling is multi-strand not solid core if they are being flexed.

jayben
Posts: 456
Joined: Mon Aug 19, 2019 9:56 pm

Re: Excavator bucket position

Sun Jun 06, 2021 8:13 am

You say that you need to measure the distance from bucket to base, does it mean that you don't need to know the position of the various arm joints, just the resulting distance? Most importantly, what accuracy do you need, and how fast must the measurements be?

To me, the idea of running low-voltage signal cables along the excavator arm seems a bit implausible; aside from electrical interference problems, it'll take a lot of effort to protect the cables, otherwise it won't be long before they are damaged. Personally, I'd go battery-powered and wireless, putting the sensors in very sturdy boxes. You could use Wifi for the network, but also some sub-1GHz modules could do the job.

For temporary fitment, you could use magnetic attachment, which makes installation on the excavator quick & easy, you'd just need a calibration exercise (standard set of movements) every time they were fitted.

With regard to the measurement method, I haven't used accelerometers for position measurement, but suspect this would probably work quite well, depending on the required speed and accuracy of the results. Another option would be UWB, see my blog https://iosoft.blog/real-time-location-ultra-wideband/

Ttscotchtape
Posts: 12
Joined: Mon Dec 14, 2020 3:20 am

Re: Excavator bucket position

Sun Jun 06, 2021 8:16 pm

pidd wrote:
Sun Jun 06, 2021 2:21 am
I wouldn't have thought latency would be a problem, however with so much metal around I don't think your magnetometer readings will be reliable.

Perhaps you could use optical time-of-flight sensors to measure ram extensions instead of using IMUs but there is probably a risk in dirtier environments.

Limited addressing of devices is annoying but you can run more than one i2c interface, however wire lengths would be problem with i2c.

SPI is good for longer lengths and SPI IMUs are available and as you say you can use other GPIO pins to select devices.

Make sure any cabling is multi-strand not solid core if they are being flexed.
Thanks for the insight! Like I said I spent hours researching to find a few of the simple answers you addressed here. I'm guessing calibrating the magnetometer for hard iron won't be enough to get reliable readings, right?

Ttscotchtape
Posts: 12
Joined: Mon Dec 14, 2020 3:20 am

Re: Excavator bucket position

Sun Jun 06, 2021 8:51 pm

jayben wrote:
Sun Jun 06, 2021 8:13 am
You say that you need to measure the distance from bucket to base, does it mean that you don't need to know the position of the various arm joints, just the resulting distance? Most importantly, what accuracy do you need, and how fast must the measurements be?

To me, the idea of running low-voltage signal cables along the excavator arm seems a bit implausible; aside from electrical interference problems, it'll take a lot of effort to protect the cables, otherwise it won't be long before they are damaged. Personally, I'd go battery-powered and wireless, putting the sensors in very sturdy boxes. You could use Wifi for the network, but also some sub-1GHz modules could do the job.

For temporary fitment, you could use magnetic attachment, which makes installation on the excavator quick & easy, you'd just need a calibration exercise (standard set of movements) every time they were fitted.

With regard to the measurement method, I haven't used accelerometers for position measurement, but suspect this would probably work quite well, depending on the required speed and accuracy of the results. Another option would be UWB, see my blog https://iosoft.blog/real-time-location-ultra-wideband/
Thanks for the reply!

I need to know the angle of the bucket, and the height and distance of the tip of the digging edge of the bucket as well the side to side distance, relative to a set point on the ground that can be set by the operator. With IMUs, I would do the calculations using trigonometry taking the angles of the IMUs and the known pin to pin distances as the hypotenuse of a right triangle. I would like to get the accuracy of the digging edge to less than half an inch if possible. If the accuracy of the IMUs in the field will be as good as they are when testing, I should be good. For the speed, I would want to be as fast as possible if it can be done economically. I was hoping for less than a quarter of a second of delay.

I was thinking of going the wireless route but I'm not experienced in what it would take to get it set up. I was assuming it would be a steep learning curve to get it all set up. I'm not too worried about damaging the wires as I can route them on top of the boom with the hydraulic lines. The biggest problem would be the sensor to get the angle of the bucket, but I could route the wires for that sensor in a hydraulic hose to protect it. If the electrical interference will be a problem, that may be reason enough to go wireless.

The point about UWB raises another interesting possibility that I need to investigate. I'd have some questions on how to get side to side distance as well as the angle of the bucket. I guess I'd probably need a sensor on the track frame, 2 on the main excavator frame, one on the stick and one on the bucket.

pidd
Posts: 3945
Joined: Fri May 29, 2020 8:29 pm
Location: Wirral, UK

Re: Excavator bucket position

Sun Jun 06, 2021 10:03 pm

Ttscotchtape wrote:
Sun Jun 06, 2021 8:16 pm
I'm guessing calibrating the magnetometer for hard iron won't be enough to get reliable readings, right?
Even if it doesn't maintain its own magnetic field it is bound to distort earth's magnetic field in a non-linear manner, maybe that could be calibrated out but it also changes shape which further complicates what happens.

I guess there is only one way to find out for sure.

Without a magnetometer it is going to be difficult to compensate for either cumulative errors or drift over time.

ghp
Posts: 2707
Joined: Wed Jun 12, 2013 12:41 pm
Location: Stuttgart Germany

Re: Excavator bucket position

Sun Jun 06, 2021 10:11 pm

Build a small scale model (from plywood, broomstick or other cheap material), using RC servo to move the parts. Attach the sensors and check your algorithms whether you achieve the precision you need when the model is moving.
As already discussed do not use magnetometer, will not work when steel is around.

When you run the model and you are confident the algorithms work, then start thinking about how to attach and connect the sensors with the real world.

jayben
Posts: 456
Joined: Mon Aug 19, 2019 9:56 pm

Re: Excavator bucket position

Mon Jun 07, 2021 7:47 am

A quick google of "ESP32 accelerometer" gives several detailed articles on communicating with an IMU wirelessly, so even if you're not experienced in that type of technology, I'd still seriously consider it. An excavator is an incredibly tough environment (mechanically & electrically) that I do think cables are going to be a major headache.

I don't think measuring magnetism is going to work at all, with so much metal around. Also you need to check that your IMU sensors remain accurate when subjected to shock loads - I'm not thinking they'll be damaged, but they might lose tracking when experiencing the high-g-force pulses of digging, resulting a gradual loss of the positional accuracy. Personally, I'd just use an accelerometer to sense the boom angle by resolving the direction of gravity in 2 dimensions, which won't be subject to gradual drift.

However, achieving half-inch accuracy will be incredibly difficult, given all the variables. It is tempting to forget all this complication, and just go optical; for example, stick some markers on the bucket & arm, and use 2 cameras to resolve the position. I have done some work with fiducial markers at https://iosoft.blog/raspberry-pi-positi ... cial-tags/ and there is also an article on resolving the position of a light-source in 2 dimensions. The key advantage is that for development you can quickly take some videos, then work on them at your leisure, testing various analysis methods without having to be on a muddy site, with construction workers wondering what on earth you are doing.

An interesting project, but not at all easy. Good luck!

Ttscotchtape
Posts: 12
Joined: Mon Dec 14, 2020 3:20 am

Re: Excavator bucket position

Tue Jun 08, 2021 2:49 am

Thanks guys. You've been very helpful.

Sounds like I'll forget I2C communication and magnetometers, and either use SPI or wireless. I'll probably end up going wireless. I've been wondering if I could find a way to add isolators on the sensors to keep them from unnecessary shocks. To get the side angles I'll see if it'll make sense to use potentiometers or magnetic angle sensors.

I already did some testing with the trigonometry, entering in the numbers manually in python and verifying by measuring them as physical triangles. The calculation method seems to be reliable, as long as the sensors will be accurate enough. I already did some testing with cheap IMU sensors, and I think if the final result will be as good on the field as it was during testing, I should get to the desired accuracy. I'll keep my fingers crossed.

Ttscotchtape
Posts: 12
Joined: Mon Dec 14, 2020 3:20 am

Re: Excavator bucket position

Sat Nov 27, 2021 4:05 pm

Hi all,
I have now implemented wireless communication. I purchased 3 ESP32 boards to connect to the raspberry pi. I'm connecting an MPU6050 IMU to each. The connection from the ESP32 to the raspberry pi is done by Wifi using MQTT. I have set the raspberry pi up as a hotspot so I don't need any other router for the communication. Everything is working except that the MQTT data seems to be jerky and unreliable.

Is it possible to get a steady IMU reading through MQTT? Does anybody have any idea on what to try? I'll send some of the code

Ttscotchtape
Posts: 12
Joined: Mon Dec 14, 2020 3:20 am

Re: Excavator bucket position

Sat Nov 27, 2021 4:06 pm

Raspberyy Pi (Python):

Code: Select all

import pygame, sys, time, re, math
#import numpy as np
MQTT_USER = 'ddig'
MQTT_PASSWORD = '35zts35d'
MQTT_TOPIC = 'a/a'
MQTT_TOPIC2 = 'a/b'

angle = 0
MQTT_data = str(0)
numeric_angleBRN_string = str(0)
angle2 = str(0)
numeric_angleBRN_string2 = str(0)
angle1 = str(0)
angle1_float = 0.0
angle2_float = 0.0

import paho.mqtt.client as mqtt

msg_arrived_flag = False


"MQTT_ADDRESS = '127.0.1.1'"
MQTT_ADDRESS = '10.10.10.10'

def on_connect(client, userdata, flags, rc):
    print("Connected with result code "+str(rc))
    mqtt_client.subscribe(MQTT_TOPIC)
    mqtt_client.subscribe(MQTT_TOPIC2)
def on_message(client, userdata, msg):
    global angle
    global MQTT_data
    angle = str(msg.payload)
    MQTT_data=(msg.topic + ' ' + str(msg.payload))
    #print(msg.topic+" "+str(msg.payload))
    msg_arrived_flag = True
    
mqtt_client = mqtt.Client()
mqtt_client.username_pw_set(MQTT_USER, MQTT_PASSWORD)
mqtt_client.on_connect = on_connect
mqtt_client.on_message = on_message
mqtt_client.connect(MQTT_ADDRESS, 1883)

Code: Select all

mqtt_client.loop_start()

while True:
    #time.sleep(.0001)
    #mqtt_client.loop_stop()
    if msg_arrived_flag:
        msg_arrived_flag = False
    
    if "a/a" in MQTT_data:
        angle1 = re.sub("[a/a,b,']","",str(MQTT_data));
    print("angle1",angle1)
    
    if "a/b" in MQTT_data:
        angle2 = re.sub("[a/b,b,']","",str(MQTT_data));
    print("angle2",angle2)
        
    #numeric_angle_string = re.sub("[b,']","",str(angle));
    #angle_float=(float(numeric_angle_string))
    angle1_float=(float(angle1))
    angle2_float=(float(angle2))
    print (MQTT_data)
    a = 0
Last edited by Ttscotchtape on Sat Nov 27, 2021 4:10 pm, edited 1 time in total.

Ttscotchtape
Posts: 12
Joined: Mon Dec 14, 2020 3:20 am

Re: Excavator bucket position

Sat Nov 27, 2021 4:06 pm

ESP32 (Arduino IDE):

Code: Select all

#include <MPU6050_tockn.h>
#include <Wire.h>
#include "PubSubClient.h" //// Connect and publish to the MQTT broker

#include "WiFi.h" // Enables the ESP32 to connect to the local network (via WiFi)

MPU6050 mpu6050(Wire);

// WiFi
const char* ssid = "Trevor";                 // Your personal network SSID
const char* wifi_password = "AmazingStuff"; // Your personal network password

// MQTT
const char* mqtt_server = "172.20.10.6"; // IP of the MQTT broker;
const char* AngleX_topic = "a/a";
//const char* AngleY_topic = "ddig/AngleX";
const char* mqtt_username = "ddig"; // MQTT username
const char* mqtt_password = "35zts35d"; // MQTT password
const char* clientID = "dp1"; // MQTT client ID

// Setup timers and temp variables
long loop_timer;
int temp;

// Display counter
int displaycount = 0;

// Initialise the WiFi and MQTT Client objects
WiFiClient wifiClient;
// 1883 is the listener port for the Broker
PubSubClient client(mqtt_server, 1883, wifiClient); 

// Custom function to connet to the MQTT broker via WiFi
void connect_MQTT(){
  Serial.print("Connecting to ");
  Serial.println(ssid);

  // Connect to the WiFi
  WiFi.begin(ssid, wifi_password);

  // Wait until the connection has been confirmed before continuing
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }

  // Debugging - Output the IP Address of the ESP8266
  Serial.println("WiFi connected");
  Serial.print("IP address: ");
  Serial.println(WiFi.localIP());

   // Connect to MQTT Broker
  // client.connect returns a boolean value to let us know if the connection was successful.
  // If the connection is failing, make sure you are using the correct MQTT Username and Password (Setup Earlier in the Instructable)
  if (client.connect(clientID, mqtt_username, mqtt_password)) {
    Serial.println("Connected to MQTT Broker!");
  }
  else {
    Serial.println("Connection to MQTT Broker failed...");
  }
}

void setup() {
  Serial.begin(115200);
  Wire.begin();
  connect_MQTT();
  Serial.setTimeout(2000);
  mpu6050.begin();
  mpu6050.calcGyroOffsets(true);

  loop_timer = micros(); 

}

void loop() {
  mpu6050.update();
  Serial.print("angleX : ");
  Serial.print(mpu6050.getAngleX());
  Serial.print("\tangleY : ");
  Serial.print(mpu6050.getAngleY());
  Serial.print("\tangleZ : ");
  Serial.println(mpu6050.getAngleZ());

    // Increment the display counter
  displaycount = displaycount +1;
  
if (displaycount > 14) {

  // PUBLISH to the MQTT Broker (topic = Temperature, defined at the beginning)
  if (client.publish(AngleX_topic, String(mpu6050.getAngleX()).c_str())) {
    Serial.println("Angle_X sent!");
  }

  // Again, client.publish will return a boolean value depending on whether it succeded or not.
  // If the message failed to send, we will try again, as the connection may have broken.
  else {
    Serial.println("Angle_X failed to send. Reconnecting to MQTT Broker and trying again");
    client.connect(clientID, mqtt_username, mqtt_password);
    delay(20); // This delay ensures that client.publish doesn't clash with the client.connect call
    client.publish(AngleX_topic, String(mpu6050.getAngleX()).c_str());
  }

 displaycount = 0;

   // PUBLISH to the MQTT Broker (topic = Humidity, defined at the beginning)
//  if (client.publish(GyX_topic, String(GyX).c_str())) {
//    Serial.println("Gyro_X sent!");
    
  }
  // Again, client.publish will return a boolean value depending on whether it succeded or not.
  // If the message failed to send, we will try again, as the connection may have broken.
  //else {
//    Serial.println("Gyro_X failed to send. Reconnecting to MQTT Broker and trying again");
//    client.connect(clientID, mqtt_username, mqtt_password);
//    delay(10); // This delay ensures that client.publish doesn't clash with the client.connect call
//    client.publish(GyX_topic, String(GyX).c_str());

 while(micros() - loop_timer < 4000); 
 //Reset the loop timer                                
 loop_timer = micros();

  //}
  
}

scotty101
Posts: 4445
Joined: Fri Jun 08, 2012 6:03 pm

Re: Excavator bucket position

Sat Nov 27, 2021 6:51 pm

I would have thought that some absolute encoders on each joint of the arm and bucket would be a better idea.

If you know the length of each arm and the angle at which each joint is, you can work out the position of the bucket.

One of the recent Hacksmith videos with their Alien Powerloader used a similar method to move the arms.
Electronic and Computer Engineer
Pi Interests: Home Automation, IOT, Python and Tkinter

Ttscotchtape
Posts: 12
Joined: Mon Dec 14, 2020 3:20 am

Re: Excavator bucket position

Sat Nov 27, 2021 7:10 pm

So far I’m pretty happy about the accuracy of the MPU6050 and it gives me the advantage of less moving parts. IMUs are also what professional systems use.I can always change it over later if needed. My problem is the speed at which the data is streamed to the Pi.

mirajoba
Posts: 3
Joined: Sat Mar 05, 2022 11:12 am

Re: Excavator bucket position

Sat Mar 05, 2022 11:17 am

Hi,
I searched the entire Internet and this is by far the best resource that i found. I am trying to do the exact same thing and i was wondering if you got it working by now. I whould be very thankful if you could update me on the projet or give me some insights on how you got it working and how it is working so far.

Ttscotchtape
Posts: 12
Joined: Mon Dec 14, 2020 3:20 am

Re: Excavator bucket position

Wed Mar 16, 2022 2:32 am

mirajoba wrote:
Sat Mar 05, 2022 11:17 am
Hi,
I searched the entire Internet and this is by far the best resource that i found. I am trying to do the exact same thing and i was wondering if you got it working by now. I whould be very thankful if you could update me on the projet or give me some insights on how you got it working and how it is working so far.
Hey, I'm glad to hear of someone else working on a similar project! I'm using ESP32 boards connected to MPU6050 IMUs, throwing the data wirelessly to a raspberry pi via MQTT, which is connected to a 7" touchscreen display. I have the trigonometry integrated into my code so that part is working nicely. My 2 biggest problems that I'm trying to figure out right now are speed on the raspberry pi code and accuracy on the ESP32.

For the speed on the raspberry pi I'm trying to figure how to integrate something like CPython to make the code faster.

I've been also been searching around for a good library to use for the sensor on the ESP32. I found one that was nice and accurate but it only allowed 180 degrees, which is not enough for this project. I'm currently using another library that allows 360 degrees of motion but it is very jumpy and inaccurate. I'd love to collaborate, if we could help each other figure out a reliable method.
Last edited by Ttscotchtape on Wed Sep 21, 2022 4:23 pm, edited 1 time in total.

mirajoba
Posts: 3
Joined: Sat Mar 05, 2022 11:12 am

Re: Excavator bucket position

Tue Mar 22, 2022 1:16 pm

Sorry for my late answer but i had a pretty busy week.
I´d love to collabborate on the project.
I for my part did a very similar thing, just with the ESP8266 instead of the ESP32 and i am sending the data from the Rasperry pi to an anroid app which is then doing the neccesary calculations and displaying the whole thing in a 3d view.
At first i had some major problems with the MPU6050 on the ESP8266, it just was not reading anything that made sense.
After trying a ton of libraries i found the MPU6050_light library (https://www.arduino.cc/reference/en/lib ... 050_light/) which is working like a charm. The X axis tilt is very percise and a full 360 degrees switching from 180 to -179 at the half way mark. The Y axis is working more or less but it seems to have some problems. (I dont need this axis at the moment because the boom of the excavator probably wont tilt unless there is something seriously wrong :D ) While doing some research i found out that it is not really possible to measure heading (also called yaw ,in our case in which way the excavator is turned) with a gyro, but with that library it somehow gives me values that seem to be working. I will have to try and see if they are accurate enough but it won't be a huge deal switching to a linear actuator for the heading (maybe that could also be somehow solved with the internal sensors of the rasperry pi or the phone but i'll have to see). Currently the stuff is not mounted on the excavator because it still is in its winter storage, so the individual components are redy but it is not working togehter just yet (i plan on doing that sometime in the next two weeks). Another point i am not to sure about is power supply of the ESPs. Currently i am thinking about two options, one being a battery on the ESP (like AA or LiPo) and the other one is to just hook them up to the excavators 12v system. The battery option whould have the benefit that the casing for The ESP and sensors could completley sealed and thus watertight, which whould be a big plus. The other option seems a to be a little more work now but much more convenient once its finished.

Ttscotchtape
Posts: 12
Joined: Mon Dec 14, 2020 3:20 am

Re: Excavator bucket position

Tue Mar 22, 2022 5:58 pm

mirajoba wrote:
Tue Mar 22, 2022 1:16 pm
Sorry for my late answer but i had a pretty busy week.
I´d love to collabborate on the project.
I for my part did a very similar thing, just with the ESP8266 instead of the ESP32 and i am sending the data from the Rasperry pi to an anroid app which is then doing the neccesary calculations and displaying the whole thing in a 3d view.
At first i had some major problems with the MPU6050 on the ESP8266, it just was not reading anything that made sense.
After trying a ton of libraries i found the MPU6050_light library (https://www.arduino.cc/reference/en/lib ... 050_light/) which is working like a charm. The X axis tilt is very percise and a full 360 degrees switching from 180 to -179 at the half way mark. The Y axis is working more or less but it seems to have some problems. (I dont need this axis at the moment because the boom of the excavator probably wont tilt unless there is something seriously wrong :D ) While doing some research i found out that it is not really possible to measure heading (also called yaw ,in our case in which way the excavator is turned) with a gyro, but with that library it somehow gives me values that seem to be working. I will have to try and see if they are accurate enough but it won't be a huge deal switching to a linear actuator for the heading (maybe that could also be somehow solved with the internal sensors of the rasperry pi or the phone but i'll have to see). Currently the stuff is not mounted on the excavator because it still is in its winter storage, so the individual components are redy but it is not working togehter just yet (i plan on doing that sometime in the next two weeks). Another point i am not to sure about is power supply of the ESPs. Currently i am thinking about two options, one being a battery on the ESP (like AA or LiPo) and the other one is to just hook them up to the excavators 12v system. The battery option whould have the benefit that the casing for The ESP and sensors could completley sealed and thus watertight, which whould be a big plus. The other option seems a to be a little more work now but much more convenient once its finished.
Awesome! The ESP32 sensors I got already have an 18650 battery holder attached but I’m not sure if battery life on a single 18650 battery will be reasonable. I’m only working on this on my spare time, so progress is not always at the speed of light.

Would you consider making contact be email?

mirajoba
Posts: 3
Joined: Sat Mar 05, 2022 11:12 am

Re: Excavator bucket position

Tue Mar 22, 2022 9:08 pm

It's also just a side project for me, so progress depends on the amount of time i have :) Email whould be great, you could just hit me up at [removed for privacy reasons] Just so you kwom i am based out of germany, so it might take me some time to respond depending on where you live.
Greetings, Michael.

awp2
Posts: 1
Joined: Tue May 03, 2022 2:03 pm

Re: Excavator bucket position

Tue May 03, 2022 2:07 pm

Hi guys, I am also very interested in this project, I am trying to create something to be used with a JCB 3CX.

Perhaps a github repo could be setup...?

Ttscotchtape
Posts: 12
Joined: Mon Dec 14, 2020 3:20 am

Re: Excavator bucket position

Wed Sep 21, 2022 5:01 pm

Hi all, I'm guessing those of you working on this project have long since graduated from the project and moved on? I had put the project on pause for a good bit due to the birth of my son! He took up quite a bit of my spare time, so I decided to pick up at a later date.

I'm curious was anyone able to successfully connect the sensors the Pi? What methods and libraries did you find to work best?

I was able to connect the sensors to the pi using MQTT but as soon as I had 2 or 3 sensors connected my speed dropped to unacceptable levels. I'm guessing I'm having problems with my code.

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