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MIT 2.007 — Holonomic Drive System

Designing a robot drive base that can move in all directions, including strafing left and right

Overview

In MIT's 2.007 Design and Manufacturing class, students design and build robots to compete against each other at the end of the semester. The class emphasizes hands-on design and manufacturing, as students are to fabricate almost every component of their robot, save for fasteners and motors.

Although the majority of students design their robots to compete on stage in the final competition, I designed my robot as an engineering demonstration instead.

I designed a holonomic drive system, which is a wheel base that allows a robot to move in any direction without having to rotate itself, i.e. it can strafe side to side or move diagonally.

role

Student

timeline

Fall 2012

Deliverables

Fully-assembled robot

MIT 2.007 Design and manufacturing I / fall 2012

Robot Design Process

mechanical engineering

Initial sketches for the component architecture

I designed my robot to be completely manufactured in 2D processes like laser cutting and water jet cutting. The design makes heavy use of captive T-nuts, a fastening method that allows for fast and easy assembly with 2D parts. 

CAD of the wheel base. Thin aluminum plates add strength while being lightweight. ABS is used to reduce weight while providing enough thickness to capture nuts and join the aluminum parts.

Center plates added to provide a platform for an articulation system. Lightening holes on the bottom plate reduce the overall weight of the robot.

Because the class does not allow off-the-shelf parts, I custom designed the wheels, which feature a 3D-printed core and washers acting as secondary wheels, which is essential for an omnidirectional drive system.

Full CAD of the robot, including custom 3D-printed wheels

Each of the four motors is individually controlled by a microprocessor flashed with custom firmware that maps directional input from a Playstation controller to velocity vectors for each motor. The left joystick drives the robot in the XY plane and the right joystick rotates it.

Full system built as designed. A black arrow marks the front of the robot, which is referenced in the controls firmware.

The designs were submitted to the course staff to be used as a reference for omnidirectional drives for future students.