Group 5 Self-Assembling Picnic Table Group Members: Lee-Jen Chen (Andy) Shi Li (Jeff) Spencer Soloduka Kwun Fong Tse (Ken) Supervisor Alex Kalamkarov

Self-assembling Picnic Table Objective: Design self-assembling collapsible furniture Once initiated by button, the assembly process requires no human contact Fully functional picnic table that can be collapsed to minimized space for storage/transportation Suitable for indoor or outdoor use Must seat at least 4 people (100 kg each) with sufficient table space Should be carried by one adult (< 50 lbs) Must be safe! 1

Final Solution Opened Mode Collapsed Mode 2

Presentation Contents Components: Chairs Table Central Transmission Motor and Battery Control System 3

The Chairs (Main Features) Torsion Spring Front Legs L-Bracket Rear Legs Prototype (Standing) Ropes Chair Surface Chair Frame Prototype (Bottom View ) 4

The Chairs (Opened / Collapsed Mechanism) Collapsing Opening 5

The Chairs (Stress Analysis) 220 lb Yield Strength of Steel ≈ 310 (MPa) 195/310 = 63% 6

The Table A ring is underneath the table for support and guidance. Top View Collapsed Mode Opened Mode A ring is underneath the table for support and guidance. 7

The Table 8

Table Pieces Table pieces are held together using 16 pieces of fabric. Side View Table Piece Top Bottom Table pieces are held together using 16 pieces of fabric. 9

Table Piece Each table piece is made of one piece of ABS plastic and 2 aluminum support channels. The U bar is for connection to the central shaft. 10

Support Channel Stress Analysis 50lb 100lb 12’’ 6” 50lb Under a 50lb load, the maximum stress on the aluminum channel is 210MPa (Yield strength of Aluminum alloy 6061-T6 is 270MPa). The maximum deflection is approx. 9mm. 11

Central Transmission A set of spur gears connects the motor and the lead screw. The screw sits on a thrust bearing. The nut does not rotate so it moves up and down. 12

Motor & Battery 24V DC gear motor, approx. 69W 179 RPM, 23.38 in-lbs 24V, 4200mAh NiMH rechargeable battery pack 5.0A discharge rate 13

Motor control circuit One-push button Checks potentiometer connected along transmission against reference resistor (R=0 -> open, R = Rref -> closed) 4-way switch reverses polarity of motor 14

Safety control circuit Purpose is to disable adjacent control circuit in the case that the table is loaded Checks 4 strain gauges mounted on each chair against four reference resistors (uses strain gauges on unloaded material for temperature compensation) Uses normally closed magnetic relay to control power to motor circuit 15

Control system – System coupling 16

Conclusion 17

Conclusions – Results (Dimension) Opened Mode Collapsed Mode 18

Conclusions – Results (Total Weight) Items Materials Weight (lb) Chair (x4) Aluminum, Steel, Plastic 24 Table Aluminum, ABS 10 Central Structure Aluminum, Steel Motor & Battery N/A 4 Control System 0.5 Total Weight: 48.5 19

Conclusions - Budget Components Cost Chair (x4) $360 Table $370 Central Structure $150 Motor & Battery $350 Control System $175 Contingency (15%): $210 Tax (15%): $242 Total: $1858 Allotted amount: $1860 20

Conclusions – What’s next Full scale prototype Procurement of materials and custom fabrication Consult technicians Design build report II Spec. components for control system Simulation Determine placement on system Assembly Testing Modifications/optimizing Final Design Report Lessons learned 21

Thank You! Supervisors Dr. Alex Kalamkarov Shane Yates Prototype Reg Peters Angus MacPherson Consultation Dr. Robert Bauer Dr. Lukas Swan Funding Shell Canada 22

Questions? 23