The core of our technology is an inertial measurement unit, or an IMU, which consists of three access gyros and accelerometers. IMU is used in an AHRS, or an attitude heading reference system. Our software integrates or fuses the gyro and accelerometer data from the IMU to estimate roll, pitch, and heading, helpful for GPS. Watch the video below as Walt gives an overview of the technology and its applications.

Roll, Pitch, and Heading Technology

What is roll, pitch, and heading? Roll, pitch, and heading is the orientation of the vehicle. Roll is the tilt angle. Pitch is the elevation angle. And heading is the azimuth angle, or the turn angle relative to North. If you add other aiding sensors such as a GPS or a GNSS multi-constellation positioning system, magnetometer, or barometer, those aiding sensors assist the system to output position and velocity estimation. IMU is the core. AHRS is the next level up. INS, or inertial navigation system, gives you velocity and position information.  

Role of GPS Technology

GPS does not have the ability to measure roll, pitch, and heading by itself. However, by adding inertial navigation and an IMU to the system and fuse that with the GPS data, then you will be able to keep track of the acceleration and the direction of travel heading, and roll and pitch information. But a GPS is simply a point measurement instrument.

A GPS is a system that triangulates based on satellite signals. But a GPS is essentially a point sensor. It is capable of measuring and reporting the position of the system at any given point. Over time, it can take those points and it can identify what is ground track heading, telling you the direction of travel. But it does not tell you the orientation of the vehicle as it travels. 

Let Us Help You

Having roll, pitch, and heading allows your robot to know its location. Integrating with other applications like GPS or GPS-aided sensors gives you more in-depth information. Click here and let Inertial Sense help you decide how to take your robotics to the next level. 

 

Learn More

The Difference Between IMU, AHRS, and IN

What Sensor Factors Do I Need for My Navigation System?

Everything You Need to Know About Attitude and Heading Reference Systems (AHRS)

 

Video transcription

Hey, I’m Walt from Inertial Sense. Today I’m talking about the technology that our company makes, and produces, and how we serve people in giving and understanding.

So at the core of our technology is an inertial measurement unit, or an IMU, which consists of three access gyros and accelerometers. That IMU is used in an AHRS, or an attitude heading reference system. What our software does is it integrates or fuses the gyro and accelerometer data from the IMU to estimate roll, pitch, and heading.

Roll, Pitch and Heading Technology

What is roll, pitch, and heading? Roll, pitch, and heading is the orientation of the vehicle. Roll would be the tilt angle. Pitch would be the elevation angle. And heading is the azimuth angle, or the turn angle relative to North.

So an IMU is the subset or the core of our product. Add to an IMU the sensor fusion and you get an AHRS, which gives you roll, pitch heading information. If you add to that system other aiding sensors such as a GPS or a GNSS multi-constellation positioning system, magnetometer, or barometer, those aiding sensors then can help the system to do position and velocity estimation. An IMU is the core. An AHRS is the next level up. And then an INS, or inertial navigation system, gives you velocity and position information.

An AHRS is used for people that only care about orientation. They’re not tracking position. Whereas inertial navigation or an INS is used for people that want to track position. And people that want to track position at a higher rate and with more accuracy than a GPS alone. Typical GPS receivers give you update rates at 20Hz, 50Hz, and sometimes even up to 100Hz. But when you fuse with an inertial measurement unit, you can give a much higher update rate than GPS provides, and you can filter out noise that you would see on a GPS system. Additionally you can provide the roll, pitch and heading information.

Sensor Performance: Why Can’t I Use GPS Alone?

It’s important to note that a GPS doesn’t have the ability to measure roll, pitch, and heading by itself, a single GPS system. If you add inertial navigation, if you add an IMU to the system and fuse that with the GPS data, then you’re able to keep track of the acceleration and the direction of travel heading, and roll and pitch information. So that’s important.

Sensor Performance: What’s The Difference Between GPS and GPS-Aided Inertial Navigation System?

A GPS is simply a point measurement instrument. But when you add the inertial aspects to that, then you’re able to identity roll, pitch, and heading. So I want to speak about what the difference is between a GPS and a GPS-aided inertial navigation system.

A GPS is a system that triangulates based off of satellites signals. But a GPS is essentially a point sensor. It’s capable of measuring and reporting the position of the system at any given point. Over time, it can take those points and it can identify what is a ground track heading, as they call it, which is to tell you the direction of travel. But it doesn’t tell you anything about the orientation of the vehicle as it travels.

A GPS-aided inertial navigation system is a, in our case, our sensor fusion, which is based on an extended Kalman filter. While it’s taking the direction vector of the IMU and the direction vector of the GPS data, and it’s correlating those two. And as a result, it’s able to identify the roll, pitch and heading at any time in addition to the position and velocity of the vehicle. And that’s unique to what a GPS-aided inertial navigation system or INS does in contrast to a GPS alone.

If you have a GPS update only, it’s kind of like having one eye and no other sensors on your body and then blinking at a slower rate. And so if you have any kind of dynamics, and you’re trying to identify what you’re doing, and you’re blinking at a slow rate, then you can only have so much observation of what’s going on in the world. The IMU, or the inertial sensors, give us the ability to have much higher update rates and smooth the updates that come from the GPS. so we can take those blanks, and we can fill in the gaps. And if any of the blanks are off in their measurements, we can also correct for those and smooth those out.

So it’s much like what our human body does if..think of a football player running down the field jostling with a helmet on, and everything’s kind of shaking. But he can take his senses from his eyes, and the ground, and his inner ear, and he can figure out what’s going on, even though he’s getting rocked here and there. That’s what the system’s doing. It’s fusing these noisy sensors because they all have noise. And it’s discerning what is actually happening in the world.

Sensor Performance: What Applications Use AHRS Sensors?

We have customers that have drones or robotics that are moving through free space. And they want to know instantaneously what the orientation and position of that vehicle is at any given time. They may be either stabilizing or controlling the vehicle, or they might be trying to identify something that’s happening off in the distance. And our system is capable of giving that information that they use for those applications.

I mean if you try to do that with a, you can’t do that with a GPS alone. A GPS will tell you, but any time you use a GPS in a solution like those, you have to have some additional software to help you understand what the orientation is. It’s probably important to say that the key differentiator is the orientation data, the roll, pitch, and heading, which you can’t get out of a GPS.