Just to let you know I am thinking about buying an IMU. I want to build a ROS robot but unfortunatly I can't decide on a chassis or electronics. I have an idea for what I could do to build a robot and that would be to use an IMU versus rotary encoders to measure the movement of a robot but I can't decide on an IMU. First of all I noticed a bunch of IMUs on robotshop that I could use. My only complaint is I have no idea what the numbers mean. For instants this IMU say this for it's G factor ±2g, ±4g, ±8g and ±16g but I have no idea what the number sign means. I know that the numbers probably mean G force but the Plus-Minus is throwing me off. I also have no idea about axis rotation and more. I know the basic concept of an IMU I just have no idea how to know what I need in a IMU. In case you guys don't know that I know this, an IMU is an electronic device that measures one's velocity or relative location. Thank you.
I don’t think the IMU measures velocity. They typically measure acceleration. If you could sample it fast enough you could calculate velocity by integrating acceleration over time. Some of the MPU’s have additional processing engines that accept downloaded applications. My current understanding is the applications are only released as binary files with very little documentation.
My limited experimentation with calculating velocity was not very gratifying. I am planning on using one in a self balancing machine to measure inclination and rate of rotation.
Nice to see someone else using the device. I look forward to your reading about your results…
Go for the MPU6050. Widely used, example code, cheap. It is not a good solution to get how much the robot has moved; they give noisy values. Optical encoder are the best way to get how many rotations the motor did.
The g factor is 9.8m/s2, which is an approximation of the earth gravity. An accellerometer falling free at sea level will measure exactly 0 in all axis. You need high n x g rate if you want to measure higher accellerations like a rocket. Some event like impacts likely overflow even the best imu, as they are in the in the order of 100-1000g.
I actually did you know what a g is but I didn’t know what the Plus-minus sign is but now I do. The sign basically means range between a positive and negative value. Like Plus-minus value of two is inbetween 2 and -2. Thank you though.
You should know I do not have the option of rotary encoders. My robot doesn’t have enough room for encoders. Thank you I’ll look into that IMU. Thanks!!!
