Calibration’s Inertial Measurement Unit (IMU) is a calibration system that keeps the drone flying stable, not wobbling, and level.
The IMU calibration system is a vital system for a drone flight. The most obvious function is to keep your drone from swinging while flying
The working principle of the calibration IMU is to detect drone movement in the horizontal plane, ascent, and decrease in altitude.
Without an excellent IMU calibration system, a drone can move beyond the pilot’s control.
For example, it could be when the drone is flying in a particular direction and then moves the pilot’s command.
In effect, the drone is difficult to control the pilot. And it can be even worse, falling because it is not stable at all.
What Does IMU Mean for A Drone?
IMU Calibration consists of many components that are connected, forming the primary system. This introductory system serves to measure the force, angular velocity, and attitude of a drone.
The components of IMU calibration are an accelerometer, barometer, gyroscope, and thermometer:
1. The accelerometer is used to measure the acceleration of a drone. When you start noticing the drone is flying at an angle or uneven. There may be a problem with the accelerometer. So, that’s when IMU calibration required for your favorite quadcopter,
However, it could be that the problem is with the gyroscope. The point is, keep calibrating the IMU on a flat surface.
2. The barometer is used to measure atmospheric pressure. However, in various DJI drones, the barometer can be used as a tool to measure the height of the drone.
The barometer will change to ATTI mode when flying the drone in an area with a weak GPS signal. This survival mode serves to keep the drone from falling.
3. A gyroscope is a small disk that rotates inside a drone. This component helps measure the drone’s attitude to keep it steady and level as it hovers in the sky.
4. The thermometer is used to keep the drone’s temperature under control. When the drone is powered on, the IMU temperature will heat up based on when it was last calibrated.
Sometimes, when calibration is carried out in hot weather, the drone will feel hot, and its performance will be impaired. That’s why drones need to be recalibrated in cold temperatures.
The above components will be integrated into an IMU calibration system. The system is capable of detecting specific differences in the attitude and movement of the drone while flying. That way, the drone won’t fly sideways or out of control.
Some drones on the market, including the DJI model, have multiple IMUs. When a drone has a problem, all of those components must be recalibrated.
However, some drones do not have an IMU, so they are at risk of having problems while flying.
Phantom 3 Standard IMU Calibration: Sample Case
Before calibrating the IMU Phantom 3, several preparations should be done, namely:
1. Take advantage of the DJI app to check.
2. Do not let the quadcopter move during the calibration process because it will cause a calibration failure.
3. It could be that the calibration is repeated because the drone is not in sync or the IMU calibration is stuck.
4. Ensure that calibration is performed in the data field.
5. Make sure the Phantom 3’s battery status is more than 50% so that the calibration doesn’t stop halfway.
How To Calibrate The Phantom 3 Standard IMU:
1. Turn on the Remote Controller and also turn on the Phantom 3. But don’t display the motor.
2. Open the application. Click “Camera.”
3. Then click “Mode” at the top of the screen.
4. Click “Sensor,” then click IMU Calibration.
5. Then click “OK” 2 times when two pop-up messages appear.
6. The calibration process starts. Wait for 5-10 minutes.
If the Phantom 3 Standard still feels out of sync or the IMU calibration stuck, recalibrate. As a further reference, here are some video tutorials that you can follow when calibrating the IMU Phantom 3 Standard:
1. DJI Support in the video titled DJI Phantom 3 | IMU Functions, Calibration and Precautions.
2. Forza Sim Racing in the video titled DJI Phantom 3 Standard IMU Calibration.3. DJI tutorial in the video titled DJI Tutorials – Phantom 3 Standard – IMU Calibration.
Selecting Best IMU for Drone
Comparing IMU to drones is not an easy matter. Each product has almost the same technology, price, strengths, and weaknesses.
The products available in the market have a variety of variants that will give you many choices and create confusion.
The following are some of the IMU manufacturers that you can rely on to produce quality products for your drone:
KVH Industries developed a fiber optic gyro (FOG) based IMU. Its flagship product is the KVH 1750 IMU.
The product has Thin Fiber miniature FOG technology with a solid-state MEMS accelerometer. Best of all, the KVH 1750 IMU has the option of a 2g, 10g, or 30g accelerometer with programmable data output rates from 1 – 1000 Hz.
2. SBG System
SBG Systems’ product is the Ellipse 2 Micro Series. This product is the most minor and highest-performance IMU series belonging to SBG Systems. It weighs only 10 grams.
3. Inertial Labs
The Inertia Lab has MEMS-based products with high performance, small size, and low power. The Inertial Labs IMU-P is an ITAR-free, temperature-calibrated IMU product available in industrial grade and tactical-needs requirements.
4. Inertial Sense
Inertial Sense is a micro-sized, high-performance MEMS IMU vendor. Inertial Sense products are suitable for various types of UAV utilization.
IMU is the flagship IMU produced by Inertial Sense. This product is precisely calibrated, incorporates an L1 GPS (GNSS) receiver, and is capable of providing a synchronized UTC output time of up to 1kHz.
EMCORE is IMU’s FOG (Fiber Optic Gyro) supplier. It has the advantage of high accuracy and is indeed designed with the requirements of SWaP for UAVs.
The best product is named EN-300. This FOG IMU product features low, high, high performance, and targeting precision.
You can also refer to some IMU calibration Arduino products for other options. It’s just that, what is clear, make sure you choose the IMU calibration product according to your needs and budget.