AUTONOMOUS ROBOTIC CHARGING ARM
AUTOMATED INFRASTRUCTURE FOR AUTONOMOUS VEHICLE FLEETS
As increasing autonomous electric vehicles take to the road, the introduction of autonomous charging has the potential to improve user experience, provide more efficient charging, and create safer conditions by removing humans from the process. This capstone Mechanical Engineering project is an electric vehicle charger capable of locating, engaging, and fully charging an electric vehicle. The main components include a microcontroller which collects and processes location data from cameras, an actuator-driven arm with several motors and linkages, and an end-effector for engagement with the charging port.
This project was completed by a team of five mechanical engineers. It was honored with the Best Overall Design Award at the end of year design expo at Carnegie Mellon University. This project would not be possible without the guidance of my professor Mark Bedillion and a whole lot of adhesives.
In this team project, I contributed significantly to the motor actuation code, the mechanical design, and the manufacture and assembly of custom parts. I took specific ownership of the display shell and the final expo poster (bottom of this page).
DESIGN REQUIREMENTS
This design is best-suited for the use case of enterprise, wherein fleets of autonomous electric vehicles could be serviced in large car bays. Designing for this type of controlled environment means that design parameters are relatively open, though target design requirements still stand as the result of stakeholder research. Such requirements include compatibility with all Tesla models, size under 4 cubic feet, maximum extension of 30 inches, and engagement with charge port in
SYSTEM COMPONENTS
The system can be broken up into three sub-components - mechanical, electrical, and computational. In the mechanical system, a wall-mounted gantry (shown above) uses a DC motor to drive a lead screw, thereby changing the carriage height. From the carriage extends a series of two linkages which are driven by servo motors. Finally, an end-effector with built-in compliance allows for precise engagement with the charge port.
The computer vision system is what drives the arm movement; a camera takes in data from the visual field and allows for the microprocessor to determine the height and depth corrections to be made to the arm. The Arduino then sends signals to each of the motors to drive them towards the target charge port.
CUSTOM COMPONENT MANUFACUTING
The majority of the parts in this assembly were made by myself and my teammates in the metals shop. Joints were made from aluminum square channel, then fitted with custom shaft collars. Other custom parts included inserts for off-the-shelf carbon fiber tubes, standoffs for all of the motors, shaft couples, and bearing races. In places where alignment was key such as the gantry carriage and motor alignment plates, parts were cut from a CNC mill.
DISPLAY SHELL
The white cardstock shell serves no other purpose but to clean up the system and make it more presentable. It was a personal project I took full ownership of in the hopes of making our work look more polished. SolidWorks was used to create a solid model that was then transformed into 2D cut patterns using Fusion 360's Slicer program. Parts were cut on a large laser cutter, and slotted pieces were painstakingly formed together by hand and glued into place. Finally, the outer shell was fit around the structure.
