Sensor Box and Cases
This box houses the battery arduino and the proximity and air quality packages. The main power switch is located on the front of this box along with the data and power ports. Holes had to be drilled on the bottom of the box to attach it to the bike rack on which the system was mounted. Initial prototyping was done in plywood and then transitioned onto ABS boxes for a more impact resistant case.
Adobe Illustrator CC 2016, Solidworks 2016 were the software used to create the shapes in vector format to be used in the laser cutter.
The Laser cutter used was in the Fab Lab at TSRB. The settings of the laser for cutting Acrylic was 20% power and 11% speed. For Plywood it was 50% power and 25% speed
The Rack was initially attached to the box with the help of nylon clamps. These clamps proved to be too weak and were snapping off during the vibrations. We then tried using metal clamps but they seemed to fail in the same way. We then decided to drill holes through the base of the ABS box and out through the bike rack. This proved to be the most effective method of securing the box down onto the rack.
• Holes drilled on the bottom for Rack screws • Rubber pads used to secure the rack to bike. The rubber prevents the rack from fishtailing. • Holes need to be drilled on the lid for the air package to be screwed on the underside of the lid. • The ABS boxes had projections on the inside which needed to be drilled down to accommodate the components.
The box is egg shaped and houses the Matrix, Raspberry and the GPS. The box is 3D printed. It consists of the top, bottom, base and the Go Pro mount. It has an acrylic window through which LEDs show the status for every sensor on the bike and the system as a whole. It also has a window for open air access for the GPS.
Solidworks 2016 was used to create solid part file. It was then exported as an STL file for use on the 3D printers.
Location: Fab Lab (TSRB) Pros: 2 printers, UV printer is perfect for the job (preferred printer for final product) Cons: Time taking
Location: DILAC Pros: An option Cons: Unable to print complex geometry of the top
Location: Athena Lab (TSRB) Pros: Super fine print resolution Cons: Very small workspace (needs precise angling for print)
Location: Invention Studio Pros: Many Printers Cons: Poor quality of print, Unable to print lip of Top
The mount must be sturdy with very little degree of freedom. It should be set such that the GPS points upward. Make sure the screw of the mount does not touch the Raspberry board.
• The matrix is unsupported on one side and was bouncing off the raspberry pins during data collection- Yoga mats were used as an absorber to prevent bouncing during the ride. Additionally the matrix was tied down with insulated wires. • The three small screws along the base of the model were not very strong and the top kept coming loose- 2 long screws were drilled through all the pieces on either sides of the GPS to keep everything in place. • The head of the cable used for the communication with the arduino is fat and prevented closing of the lid- The head needs to be shaved. • At times the holes were filled with material- The holes had to be drilled in the workshop
The Base and Bottom needs holes drilled into them for the two long screws that secure the parts together. The walls in the Bottom model needs to be raised slightly to provide support for the matrix.