Remote control tarantula

From DDL Wiki

(Difference between revisions)

Jump to: navigation, search

Revision as of 00:01, 24 September 2007

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 head of the spider, and pivot to steer. A second set of wheels attached to the battery cover support the abdomen of the spider, but do not contribute to steering or propulsion. 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 input form the remote control; rather it turns when the motor is running counterclockwise or receiving a “backwards” input. The drive wheels are setup such that depending on the direction the motor is running, the wheels will align to a certain orientation. The drive shaft for the wheels descends vertically from the head of the spider and connects to the drive wheels at a 90° angle. The bracket which holds the axle sits in two slots which allow it to rotate along the axis of the drive shaft. When the motor runs there is a net torque on the drive wheel axle, causing the bracket and axle to rotate if they are able. The wheels turn 45° relative to the centerline of the Tarantula if the motor is running backwards, and point straight ahead if the motor is running forwards. 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 AAA 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

The amount of environmental impact attributable to a single Tarantula is relatively negligible. But when the large volume of numbers produced is taken into account, the amount of pollutant emissions, economic demands, and energy needs become a larger factor to consider. The apparently environmentally harmless product becomes more a larger problem when considered in the grander scale of manufacturing and production.

The method used to calculate the environmental and economic impact of the Tarantula involves the use of data provided through the Economic Input-Output Life Cycle Assessment (EIO-LCA) database. In order to get a proper appreciation of the impact of the product, all calculations and measurements are done in terms of millions of dollars of economic activity. The database compiles information pertaining to the economic demands, pollutants emitted, energy demands, even the labor needs for certain sectors of different industries. Once a sector’s impact is calculated, the information pertaining to the contributing factors for each million dollars of activity can be accessed and compared.

Production of the Tarantula pertains primarily to sector 33930 - Dolls, Toys, and Game Manufacturing. However, over the lifetime of the product’s use, multiple purchases of batteries are required. As a result, the economic and environmental impact of the product is also linked to sector 335912 - Primary Battery Manufacturing. The focus of this analysis is to observe the main sources of emissions and demand for energy. The types of emissions observed are greenhouse gases, conventional air pollutants, and toxic releases.

For sector 33930, the primary consumer of energy is power generation itself. It consumes nearly three times the energy as the next two sectors, which are toy manufacturing and paperboard mills. These three sectors combined contribute for approximately half of the total energy required, amounting to 3.99 TJ/$1 Million for Production. The non-toxic emissions produced are also primarily attributable to power generation. However, the toxic releases caused by sector 33930 stem from the chemical nature of the type of manufacturing methods used. Of the 46.4kg/$1M, approximately 20 kg is caused by toy manufacturing and plastics material manufacturing.

@@ Line 192: / Line 192: @@
 ==Design for manufacturing and assembly==
 ==Failure mode effects analysis==
-[[Image:RC_Tarantula_FMEARatingScale.jpg|FMEA Rating Scale Used]]
 ==Design for environment==