IMU Accelerometer & Gyroscope

This example shows accelerometer and gyroscope at a combined/synchronized 500 hz rate using the onboard IMU. Returns acceleration [m/s^2] and angular velocity [rad/s].

Demo

Setup

Please run the install script to download all required dependencies. Please note that this script must be ran from git context, so you have to download the depthai-python repository first and then run the script

git clone https://github.com/luxonis/depthai-python.git
cd depthai-python/examples
python3 install_requirements.py

For additional information, please follow installation guide

Source code

Also available on GitHub

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#!/usr/bin/env python3

import cv2
import depthai as dai
import time
import math

# Create pipeline
pipeline = dai.Pipeline()

# Define sources and outputs
imu = pipeline.createIMU()
xlinkOut = pipeline.createXLinkOut()

xlinkOut.setStreamName("imu")

# enable ACCELEROMETER_RAW and GYROSCOPE_RAW at 500 hz rate
imu.enableIMUSensor([dai.IMUSensor.ACCELEROMETER_RAW, dai.IMUSensor.GYROSCOPE_RAW], 500)
# above this threshold packets will be sent in batch of X, if the host is not blocked and USB bandwidth is available
imu.setBatchReportThreshold(1)
# maximum number of IMU packets in a batch, if it's reached device will block sending until host can receive it
# if lower or equal to batchReportThreshold then the sending is always blocking on device
# useful to reduce device's CPU load  and number of lost packets, if CPU load is high on device side due to multiple nodes
imu.setMaxBatchReports(10)

# Link plugins IMU -> XLINK
imu.out.link(xlinkOut.input)

# Pipeline is defined, now we can connect to the device
with dai.Device(pipeline) as device:

    def timeDeltaToMilliS(delta) -> float:
        return delta.total_seconds()*1000

    # Output queue for imu bulk packets
    imuQueue = device.getOutputQueue(name="imu", maxSize=50, blocking=False)
    baseTs = None
    while True:
        imuData = imuQueue.get()  # blocking call, will wait until a new data has arrived

        imuPackets = imuData.packets
        for imuPacket in imuPackets:
            acceleroValues = imuPacket.acceleroMeter
            gyroValues = imuPacket.gyroscope

            acceleroTs = acceleroValues.timestamp.get()
            gyroTs = gyroValues.timestamp.get()
            if baseTs is None:
                baseTs = acceleroTs if acceleroTs < gyroTs else gyroTs
            acceleroTs = timeDeltaToMilliS(acceleroTs - baseTs)
            gyroTs = timeDeltaToMilliS(gyroTs - baseTs)

            imuF = "{:.06f}"
            tsF  = "{:.03f}"

            print(f"Accelerometer timestamp: {tsF.format(acceleroTs)} ms")
            print(f"Accelerometer [m/s^2]: x: {imuF.format(acceleroValues.x)} y: {imuF.format(acceleroValues.y)} z: {imuF.format(acceleroValues.z)}")
            print(f"Gyroscope timestamp: {tsF.format(gyroTs)} ms")
            print(f"Gyroscope [rad/s]: x: {imuF.format(gyroValues.x)} y: {imuF.format(gyroValues.y)} z: {imuF.format(gyroValues.z)} ")

        if cv2.waitKey(1) == ord('q'):
            break

Also available on GitHub

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#include <cstdio>
#include <iostream>

#include "utility.hpp"

// Inludes common necessary includes for development using depthai library
#include "depthai/depthai.hpp"

int main() {
    using namespace std;
    using namespace std::chrono;

    // Create pipeline
    dai::Pipeline pipeline;

    // Define sources and outputs
    auto imu = pipeline.create<dai::node::IMU>();
    auto xlinkOut = pipeline.create<dai::node::XLinkOut>();

    xlinkOut->setStreamName("imu");

    // enable ACCELEROMETER_RAW and GYROSCOPE_RAW at 500 hz rate
    imu->enableIMUSensor({dai::IMUSensor::ACCELEROMETER_RAW, dai::IMUSensor::GYROSCOPE_RAW}, 500);
    // above this threshold packets will be sent in batch of X, if the host is not blocked and USB bandwidth is available
    imu->setBatchReportThreshold(1);
    // maximum number of IMU packets in a batch, if it's reached device will block sending until host can receive it
    // if lower or equal to batchReportThreshold then the sending is always blocking on device
    // useful to reduce device's CPU load  and number of lost packets, if CPU load is high on device side due to multiple nodes
    imu->setMaxBatchReports(10);

    // Link plugins IMU -> XLINK
    imu->out.link(xlinkOut->input);

    // Pipeline is defined, now we can connect to the device
    dai::Device d(pipeline);

    bool firstTs = false;

    auto imuQueue = d.getOutputQueue("imu", 50, false);
    auto baseTs = std::chrono::time_point<std::chrono::steady_clock, std::chrono::steady_clock::duration>();

    while(true) {
        auto imuData = imuQueue->get<dai::IMUData>();

        auto imuPackets = imuData->packets;
        for(auto& imuPacket : imuPackets) {
            auto& acceleroValues = imuPacket.acceleroMeter;
            auto& gyroValues = imuPacket.gyroscope;

            auto acceleroTs1 = acceleroValues.timestamp.get();
            auto gyroTs1 = gyroValues.timestamp.get();
            if(!firstTs) {
                baseTs = std::min(acceleroTs1, gyroTs1);
                firstTs = true;
            }

            auto acceleroTs = acceleroTs1 - baseTs;
            auto gyroTs = gyroTs1 - baseTs;

            printf("Accelerometer timestamp: %ld ms\n", duration_cast<milliseconds>(acceleroTs).count());
            printf("Accelerometer [m/s^2]: x: %.3f y: %.3f z: %.3f \n", acceleroValues.x, acceleroValues.y, acceleroValues.z);
            printf("Gyroscope timestamp: %ld ms\n", duration_cast<milliseconds>(gyroTs).count());
            printf("Gyroscope [rad/s]: x: %.3f y: %.3f z: %.3f \n", gyroValues.x, gyroValues.y, gyroValues.z);
        }

        int key = cv::waitKey(1);
        if(key == 'q') {
            return 0;
        }
    }

    return 0;
}

Got questions?

We’re always happy to help with code or other questions you might have.