SofaMatic

A couch that gets you places.

Frame

• Custom made from one-inch square steel tube.



• Bolts together from mostly-flat pieces





• 90lbs if made from 1/16″ wall once-inch square mild steel tube.

Propulsion

• Motors: 2 x MY1020ZX
• 600W, 36V planetary geared motor with cooling fan
• 10 tooth #420 sprocket, 60:9 gear reduction
• 11.9 N*m torque @ 21.3 amps, 550rpm unloaded
• $115 @ TNC Scooters
• Controller: Roboteq MDC2250
• 2 x 60A channels, 7-50V DC
• Acceleration profiles, joystick mixing for tank steering, etc.
• $395 from Roboteq
• Gearing: 6:1 single-reduction #420 chain drive
• (this differs from the dual-reduction gearing in the drawings)
• Wheel gears: 60t #420 sprocket from Azusa Engineering (drilled for 6-hole disc brake mount)
• Top Speed @ no load: 7.5mph
• Batteries: 3 x Trojan 30XHS
• 105-130Ah, 57min @ 75A, 225min @ 25A
• 66lbs
• $199 from Battery Systems

Wheels

• Drive Wheels: Surly Large Marge
• 65mm double wall
• Drive Tires: Surly Endomorph
• “It’s the highest-volume production bicycle tire on the market.”
• “specifically designed for soft conditions such as packed snow and sand”
• 3.7″ wide, 29″ tall
• Drive Hubs: Shimano XT M776
• 20mm thru axle, 36h, 110mm
• Front Wheels: Hamilton S-7112-PR
• $174 @ service caster corp

Control

• Arduino-based microprocessor control system.
• Wireless using XBee radios.
• Smaller-scale working example.

Cushioning

• The seat back and sides will have thick foam cushions.



• All exposed leading edges of the frame will be covered with dense foam padding.