Contents
What does an IMU measure?
An inertial measurement unit (IMU) measures and reports raw or filtered angular rate and specific force/acceleration experience by the object it is attached to. Data outputs for an IMU are typically body-frame accelerations, angular rates and (optionally) magnetic field measurements.
How is angular position measured?
Angular position is quantified by measuring how far the body is rotated from the reference position. The angular position is denoted by the symbol theta (θ) and can be measured in degrees (°), radians (rads) or revolutions.
Is angular position a vector?
Angular displacement is a vector quantity, which means that angular displacement has a size and a direction associated with it. As the object rotates from point “0” to point “1”, it rotates about an axis, so the direction of the angular displacement is measured along the axis.
How to extract one measurement between IMU sensors?
Combination of multiple sensors to extract one measurement Between IMU sensors: Attitude Heading Reference System (AHRS) Can also fuse IMU with other sensors (e.g. GPS) Helps to minimize effects of bias Many approaches and types of filters/algorithms Some sensors do these calculations onboard 17 Gravity and Magnetic Field as References
How to estimate orientation by integrating angular velocities?
Estimate orientation by integrating angular velocities Gyroscope data outputs angular velocity (deg/s) Riemann sum provides discrete-time approximation of integration Riemann Sum Estimation of Orientation: ● θ approx (t) = θ approx (t-1) + ω(t-1)*Δt
What makes up an Inertial Measurement Unit ( IMU )?
Inertial Measurement Units Inertial Measurement Units Aditya Chaudhry, Chris Shih, Alex Skillin, Derek Witcpalek EECS 373 Project Presentation Nov 12, 2018 Outline ● Where IMUs are used ● What makes up an IMU ● How to choose one ● How to get useful data 2 IMUs
How does IMU keep track of moving ground vehicles?
○ IMU with GPS can keep track of moving ground vehicles ● Attitude and Heading Reference System ○ Calculate a vehicle’s heading relative to magnetic north ● Orientation Sensors ○ Phones, tablets, smart watches use to keep track of their orientation 4