A286 - Lego RCX Replacement

Materials Selection

• Aluminum 6061-T6 for construction parts
• ABS Plastic for electronics enclosures

Part Dimensions

• Largely based on other kits
• Based on standard bolt, nut, and shaft sizes
• Easy to machine with equipment in machine shop

Sensors and Motors

• Selected for common robotics class tasks
• Line following, mobility, object locating, impact detection

Flat bars, channel bars, plates, shafts, wheels

• Students need to work with constrained set of parts

SolidWorks models for all parts

• Allows students to model their designs with CAD programs

Parts fit together and come apart easily

• Rounded edges allow different angles
• Facilitates iterative design process

Gears and Shafts

• Gear ratios are factors of hole size
• Availability of gear sizes restricted design choices

Custom Parts

• Can be fabricated from tools in machine shop
• Allows students to be more familiar with manufacturing processes
• Requires more technical documentation
• Requires planning to fit with rest of kit

Enclosures

• Designed to fit with rest of kit
• Small and form fitting with electronics
• Makes packaging more compact

Central control brick

• Fits with rest of parts, is portable, and self powered
• Uses C programming language
• More standard compared to current solutions
• Easy to translate processes into code

Uses USB communication

• Communication is 2-way to help with debugging
• Encourages cooperation between many disciplines

The current thickness for the parts is 1/16". This was determined after running failure analysis on several types of aluminum at differing thicknesses. A thickness of 1/16" was found to be sufficiently strong against failure while being small enough to be usable as parts in the robot.

The center-to-center hole distance is 1/2". A spacing of 1/2" was found to be sufficiently strong against shear out and tension while keeping the parts compact. This also corresponds to the hole diameter, which is set to 1/4". In addition, the spacing between the hole center and the end of the part is 1/4". This allows parts to be set end-to-end and have a consistent 1/2" spacing between the holes. This way, the user can attach a flatbar as a bracket to hold two pieces end-to-end.

• Miniature metal gear motor
• 341 rpm
• 29mm x 12mm x 10mm
• Good torque to speed ratio
• Parallax QTI Light Sensor
• Parallax QTI Light Sensor
• Infrared Light sensor
• Concave button
• Tested to 10,000,000 cycles
• Sharp IR Range Sensor
• 8-60 inch range

Below is a video demonstration of our project. The video is supported on Mozilla Firefox, Google Chrome, and Opera Web Browser. If your browser is not supported you can download the video here: Download Link. Alternatively you can right-click on the video and click save-as to download the video.