COMPLETED -- This is my Senior Design Project. My group, known as Lexington PWR, worked on building an affordable and easy to use home gym system. The project was commissioned and partially funded by Lexcelon, a Lexington based startup. The operation of the machine was inspired by rowing machines. The resistance is provided by a stepper motor which applies a torque on an armature that would press against the retraction mechanism. The device provides three modes for the user to get a full workout experience. The first mode is a constant resistance mode, which as the name implies provides My focus for this project was both on the power supply and the user interface. The power supply provides 120 W of power (12 VDC/10 A) to operate the motor and the user interface after being stepped down through a step down converter. A simple rocker switch was used for turning the device on and off with ease. The user interface includes three seven segment displays to display the resistance the user feels, three buttons to change the amount of resistance and cycle through three workout modes, and a SAMD20 microcontroller chip to control the entire unit. The UI also connects to a hall effect sensor which is mounted near the retraction mechanism, equipped with 6 rare Earth magnets, to measure rotational speed of the retraction. Below are some images of the engineering process.