Tilt Sensor, Accelerometer or Gyro's?

Hitec robotics including ROBONOVA humanoid, HSR-8498HB servos, MR C-3024 Controllers and RoboBasic
6 postsPage 1 of 1
6 postsPage 1 of 1

Tilt Sensor, Accelerometer or Gyro's?

Post by Kelpy » Tue Oct 12, 2010 4:25 pm

Post by Kelpy
Tue Oct 12, 2010 4:25 pm

Hi.

I'm new to this hobby, and am a little confused about some of the sensors you all seem to fit to your RN.

Can someone please explain to me, in simple terms, the difference in those 3 sensors?

I basically want him to be steadier on his feet, and to automatically get up should he fall over.

Many thanks.
Hi.

I'm new to this hobby, and am a little confused about some of the sensors you all seem to fit to your RN.

Can someone please explain to me, in simple terms, the difference in those 3 sensors?

I basically want him to be steadier on his feet, and to automatically get up should he fall over.

Many thanks.
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Post by Kelpy » Fri Oct 15, 2010 5:22 pm

Post by Kelpy
Fri Oct 15, 2010 5:22 pm

Anybody???
Anybody???
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Post by Fritzoid » Fri Oct 15, 2010 6:32 pm

Post by Fritzoid
Fri Oct 15, 2010 6:32 pm

I'll take a shot at it.

An accelerometer as the name suggests measures the acceleration of the device in 1, 2 or 3 directions. A typical accelerometer used in robotics can measure the acceleration of between 0 and 5 times the acceleration of gravity, denoted by the letter g.

Under static conditions (robot not moving) a 2 or 3-axis accelerometer can be used to find the direction of the gravity vector, i.e the earth. This in turn can be used to determine the attitude (tilt) of your robot. Unfortunately humanoid robots are far from static and even small motions can cause high accelerometer readings. For this reason they are really only good for gross measurements. Basically all you can tell is whether the robot has fallen over and in which direction. As a result an accelerometer is often sold as or referred to as a tilt sensor. This is the case with the Robonova tilt sensor, it's acctually an accelerometer.

There are other types of sensors that can also measure tilt, you may see these around in catalogs. They are rarely used on the Robonova.

Gyroscopes on the other hand are very common. They measure the rate of angular motion or twist. By integrating the gyro readings over time it is also possible to determine the attitude of your robot. This turns out to be a more reliable method for active control of a humanoid robot than the accelerometer technique. So you'll get better stability with a gyro than an accelerometer.

Gyros aren't so good at telling if the robot has fallen over though, so an accelerometer/tilt sensor is nice to have too.

Also, the Robonova accelerometer (tilt sensor) is easy to install, just push it onto the controller. You will have to come up with a custom solution for hooking up and mounting any gyros.

Fortunately there are plenty of other posts around here on that subject.

Have fun.
I'll take a shot at it.

An accelerometer as the name suggests measures the acceleration of the device in 1, 2 or 3 directions. A typical accelerometer used in robotics can measure the acceleration of between 0 and 5 times the acceleration of gravity, denoted by the letter g.

Under static conditions (robot not moving) a 2 or 3-axis accelerometer can be used to find the direction of the gravity vector, i.e the earth. This in turn can be used to determine the attitude (tilt) of your robot. Unfortunately humanoid robots are far from static and even small motions can cause high accelerometer readings. For this reason they are really only good for gross measurements. Basically all you can tell is whether the robot has fallen over and in which direction. As a result an accelerometer is often sold as or referred to as a tilt sensor. This is the case with the Robonova tilt sensor, it's acctually an accelerometer.

There are other types of sensors that can also measure tilt, you may see these around in catalogs. They are rarely used on the Robonova.

Gyroscopes on the other hand are very common. They measure the rate of angular motion or twist. By integrating the gyro readings over time it is also possible to determine the attitude of your robot. This turns out to be a more reliable method for active control of a humanoid robot than the accelerometer technique. So you'll get better stability with a gyro than an accelerometer.

Gyros aren't so good at telling if the robot has fallen over though, so an accelerometer/tilt sensor is nice to have too.

Also, the Robonova accelerometer (tilt sensor) is easy to install, just push it onto the controller. You will have to come up with a custom solution for hooking up and mounting any gyros.

Fortunately there are plenty of other posts around here on that subject.

Have fun.
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Post by Gort » Fri Oct 15, 2010 7:49 pm

Post by Gort
Fri Oct 15, 2010 7:49 pm

I would look through past posts on the Robonova. There is a lot of information on gyros and accelerometers for the Robonova. Check the Robonova wiki. There is also information about hooking up a compass to the Robonova too. :)
I would look through past posts on the Robonova. There is a lot of information on gyros and accelerometers for the Robonova. Check the Robonova wiki. There is also information about hooking up a compass to the Robonova too. :)
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Post by Kelpy » Sat Oct 16, 2010 5:41 pm

Post by Kelpy
Sat Oct 16, 2010 5:41 pm

Many thanks guys. I'll do some more research, but I think a pair of gyro's and an accelorometer is what I need.
Cheers.
Many thanks guys. I'll do some more research, but I think a pair of gyro's and an accelorometer is what I need.
Cheers.
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Post by ozfiddler » Tue Oct 26, 2010 4:59 am

Post by ozfiddler
Tue Oct 26, 2010 4:59 am

Hey Fritzoid - thanks for that excellent explanation! I had been wondering about the differences and you've made it very clear.
Hey Fritzoid - thanks for that excellent explanation! I had been wondering about the differences and you've made it very clear.
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