The calibration cube is a mechanical jig used for calibrating gyroscopes, accelerometers and magnetometers. This repository also contains file for different sensor brackets for mounting different sensors on the calibration cube, and a protractor for precisely rotating the cube around different axis so that the performance of the calibrated sensors can be tested.
The calibration cube is comprised on three horizontal levels separated by vertical spacers. The middle and top levels feature grids of mounting holes and cut-outs for securing the sensors and additional equipment such as batteries. Each of the eight corners of the cube function as sockets that ensure alignment when the calibration cube is mounted on the protractor. The calibration cube is designed to be laser-cut from 3 mm MDF and press-fit assembly.
The Calibration Cube Protractor is a gimbal that allows the Calibration Cube to be precisely rotated around a single axis in 5° steps. The Calibration Cube can be mounted at any orthogonal orientation for rotations around all three axis. This allows evaluation of accelerometer performance (as pitch and roll) through rotations around a horizontal axis; and magnetometer performance (as yaw) through rotations around the vertical axis. The protractor is made from 5 mm laser cut acrylic plastic and assembled with glue. It does not feature any metallic parts as these may interfere with the magnetometer.
The design was created from a single 3D part designed in SolidWorks and selected surfaces then exported as DXF files. The SolidWorks part itself is not intended to be manufactured. The DXF files were imported to Inkscape to add engraved text and layout the parts for the laser cutter. The parts must be used at the correct orientation to achieve a flush fit given the natural chamfer created by the laser cutter. The bottom side of the cog is indicated by the engraved "Bottom" label.
The photo below shows the protractor being used to test the accelerometer performance of nine x-BIMUs.
The sensor brackets mount on the calirbation cube and secure deiffernt sensors in alginemnt. Each bracket is designed to be laser-cut from 3 mm MDF. The current files include brackets for the: