Remote control tarantula

From DDL Wiki

Contents 1 Executive summary 2 Customer needs 3 Function 4 Forward Locomotion 5 Leg Movement 6 Turning 7 Power Train 8 Product use 9 Components 10 Design for manufacturing and assembly 11 Failure mode effects analysis 12 Design for environment 13 EIOLCA

Executive summary

Customer needs

Function

The Tarantula is a variant of commonly seen remote controlled toys. The user holds a controller which sends radio signals to the Tarantula and controls its movement. The appeal of this toy is the novelty of a large moving spider as a remote controlled vehicle. Also, the realism of the device adds to the user’s enjoyment by allowing him or her to scare others with it.

Forward Locomotion

The controller only has two outputs, forward and back. During “forward” the motor runs in a clockwise direction engaging the drive wheels through a gear system. The drive wheels are under the abdomen of the spider, while the steering wheels are under the head. When moving forward, the steering wheels are pointed straight and the spider moves in a straight line. The drive wheels are vertically offset from each other to mimic a “crawling” motion and add to the realism. Due to the high gear ratio, the movement is slower than most RC toys, similar to what one would expect of an actual spider. However, the toy only functions well on very flat surfaces, and will become stuck on carpet or small obstacles.

Leg Movement

When the motor is engaged, a turn table in the head of the spider also spins. This table is cam shaped which causes it to asymmetrically engage 8 levers which are connected to the 8 legs of the spider. As the turn table engages the legs they are lifted up, but pulled back down by gravity as the turn table disengages them. This up and down motion of the legs mimics the crawling of a spider and it is central to the realism and novelty of the product.

Turning

The spider has no specific steering mechanism; rather it turns when the motor is running counterclockwise or receiving a “backwards” input.  The gearing is such that when the motor is running backwards the steering wheels turn counterclockwise approximately 45 degrees.  This causes the spider to turn while it is moving backwards, allowing the user to control the eventual destination of the device.

Power Train

The spider is powered by two AA batteries connected in series. This powers the small motor and electronics (circuit board, LED eyes). The motor is connected to a gearing system with a large gearing ratio by a worm gear. This results in a slower movement, but higher torque on the drive wheels.

Product use

Components

Part #	Part name	QTY	Function	Materials	Manufacturing Process	Picture
001	Cover Screws	13	Holds bottom cover in place	Steel	Cold headed, Thread Rolled
002	Inner Flat-headed screw	2	Holds circuit board and LED eye in place on interior of machine	Steel	Cold headed, Thread rolled
003	Battery Cover	1	Covers, protects bottom of tarantula	Plastic	Injection Molded, hand modified
004	Back Wheel housing	1	Covers rear wheels Holds rear wheels in place	Plastic	Injection Molded
005	Back Wheel	2	Holds weight of majority of tarantula, allows it to roll on ground	Plastic	Injection Molded, smoothed
006	Small Leg	4	Aesthetic legs that move asymmetrically as tarantula rolls Covered in fake "fur"	Plastic	Injection Molded
007	Medium Leg	2	Aesthetic legs that move asymmetrically as tarantula rolls Covered in fake "fur"	Plastic	Injection Molded
008	Large leg	2	Aesthetic legs that move asymmetrically as tarantula rolls Covered in fake "fur"	Plastic	Injection Molded
009	Feelers	2	Aesthetic feelers that are in a fixed, forward-facing position to mimic a spider Covered in fake "fur"	Plastic	Injection Molded
010	Driving Wheel 1	1	Takes torque of motor, drives the front axle Off-center axle hole	Plastic	Injection Molded, smoothed
011	Driving Wheel 2	1	Shares axle with Driving wheel 1 Off-center axle hole	Plastic	Injection Molded, smoothed
012	Plastic Protection housing	1	Holds motor and gearing in place on interior of robot Provides internal support for robot	Plastic	Injection Molded
013	Back Wheel Axle	2	Each axle has a Back wheel fitted on it, allows back wheels to roll	Steel	Cut wire, smoothed	Image:RC Tarantula Part 013.jpg
014	Battery Cover Washer	1	Washer for battery cover screw	Plastic	Punched	Image:RC Tarantula Part 014.jpg
015	Gear 1	2	Short and fat gear, used for power transmission	Plastic	Injection Molded
016	Gear 2	1	Medium gear, wide, used for power transmission	Plastic	Injection Molded
017	Gear 3	2	Thin, tall gear, used for power transmission	Plastic	Injection Molded
018	Gear 4	1	Large gear with cam, used to actuate tarantula leg movement	Plastic	Injection Molded
019	Axle 1	1	Smooth, long axle used to hold Gear 3 (both of them) on the interior of tarantula	Steel	Cut wire, smoothed
020	Axle 2	1	Smooth, medium axle Used on interior to hold Gear 1	Steel	Cut wire, smoothed
021	Axle 3	1	Smooth, short, and wide axle	Steel	Cut wire, smoothed
022	Axle 4	1	Long, double-roughed axle Used on interior to hold gears	Steel	Cut wire, smoothed, stamped rough areas
023	Axle 5	1	Short, double-roughed axle	Steel	Cut wire, smoothed, stamped rough areas
024	Axle Cap	1	Axle endcap	Plastic	Injection Molded	Image:RC Tarantula Part 024.jpg
025	Switch Assembly	1	Electronic Off/On switch with 2 wires and small circuit	Circuit Board (silicon), metal wires, plastic switch	Assembly
026	Switch Cover	1	Covers switch, protects it	Plastic	Injection Molded
027	Motor Assembly	1	Motor that powers tarantula Worm-geared output shaft	Metal wiring, magnets, Metal casing, plastic gearing	Assembly
028	Circuit Board Assembly	1	Remote receiver has attached antenna controls motor function	Circuit Board (silicon), metal wires	Assembly
029	LED Assembly	1	Aesthetic assembly to make eyes of tarantula glow as it moves	Circuit (silicon), metal wires, LED	Assembly
030	Tarantula exterior bottom	1	outer shell of tarantula	Plastic	Injection Molded, hand modified
031	Tarantula exterior top	1	outer shell of tarantula covered in fake "fur"	Plastic	Injection Molded, hand modified
032	Battery Connector	1	Small flat metal piece that connects + end of one battery to - end of the other	Steel	Cut sheet metal	Image:RC Tarantula Part 032.jpg
033	Battery + connector	1	connects to + end of batteries in series, connects to wire which runs to motor	Steel	Cut sheet metal	Image:RC Tarantula Part 033.jpg
034	Battery - connector	1	connects to - end of batteries in series, connects to wire which runs to motor	Steel	Cut sheet metal	Image:RC Tarantula Part 034.jpg
035	Metal screw receiver	1	threaded cylinder of steel to receive a screw mounted inside bottom plastic exterior to stop screw from tearing into plastic	Steel	threaded cylinder	Image:RC Tarantula Part 035.jpg
036	Drive Wheel Mount	1	Holds drive axle in place	Plastic	Injection Molded

Design for manufacturing and assembly

Failure mode effects analysis

Design for environment

EIOLCA