Tilt Sensor, Accelerometer or Gyro's?
Tilt Sensor, Accelerometer or Gyro's?
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.
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.
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.
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.
