ErgoDesk : Automatic height adjustment of a desk

Abstract: The purpose of this project was to track the posture of aperson sitting by a desk, and then use the information toadjust the desk to achieve an optimal height for the user.The solution was to track the angle of the users forearm relativeto the desk’s horizontal plane, which should be aroundzero degrees for an ergonomic posture. Two Light EmittingDiodes (LEDs) in different colours were attached tothe user, one at the elbow and one at the wrist. The LEDswere tracked with a camera connected to a laptop runningOpen Source Computer Vision Library (OpenCV). Windowtinting was placed on the camera lens so that only theLEDs and other strong light sources were visible. By usingOpenCV, coordinates for the two LEDs were given. Withthe coordinates found, the angle of the users arm couldbe calculated and the height of the desk evaluated. Informationabout necessary height adjustments were sent fromthe laptop to an Arduino via Bluetooth. The Arduino thencontrolled a stepper motor by sending signals to a stepperdriver, making the motor rotate, thus adjust the height ofthe desk.The desk was a single leg laptop desk. The leg consistsof two tubes. The lower, outer tube was connected to thefoot while the upper inner tube, which ran freely in theouter tube, was connected to the tabletop. The height wasadjusted with a lead screw positioned parallel to the leg.The nut on the lead screw was connected to the outer lowertube. When the motor rotated so did the lead screw, liftingthe table top up or lowering it.