350
`Chapter ‘[8 - Replicating Renowned Droids
`
`
`
`Introduction
`
`If you’re a fan of science fiction novels and movies like we are, it’s quite natural‘
`to try and reproduce some of their leading robotic characters. Obviously, you
`cannot hope to get even close to the complex behavior they Show in films.Tha1; 9
`would be an impossible task even with resources Well beyond those of the
`MINDSTORJVIS system, but even with a much more modest goal in mind, you,
`will discover this is not an easy tasl<.The difficulties come from trying to model a
`small scale robot after a large—sized one with
`complex shape; something not
`
`easy to reproduce using LEGO parts.
`In this chapter, we describe the clones of two veiy famous robots: R2—D2
`fiom George Lucas’ Star l/Vars saga, probably the most beloved android of all time,
`and Johnny Five/Number Five from John Badhanfs film Short ClI’CI/I2'f.W€ chal-
`lenged ourselves to build both of them using only MINDSTORMS parts, plus
`an optional third motor, with both of them designed for light following, a matter
`not yet explored in the book.As always, you’re invited to use our models as
`starting points for your own variations either in shape or functionality.
`
`if
`
`Building an R2-D2-Style Droid
`
`The “real” R2—D2 is essentially made of a cylindrical body culminating in a
`hemispherical head. Two rigid legs come out from its sides, ending with the
`wheels that provide motion to the robot. R2—D2 is a differential drive. The orig—
`inal character also features a front retractable wheel used only under certain con-
`ditions; in our model this is the third supporting point necessaiy for balance.
`Figure 18.1 shows our R2—D2.You’ll notice it’s more of a symbolic represen-
`tation than a realistic model! The RCX, mounted vertically, constitutes the main
`part of the body, while the head is mimicked by a compound structure of tubes.
`
`
`
`
`Chapter ‘[8 - Replicating Renowned Droids
`
`
`
`Introduction
`
`If you’re a fan of science fiction novels and movies like we are, it’s quite natural‘
`to try and reproduce some of their leading robotic characters. Obviously, you
`cannot hope to get even close to the complex behavior they Show in films.Tha1; 9
`would be an impossible task even with resources Well beyond those of the
`MINDSTORJVIS system, but even with a much more modest goal in mind, you,
`will discover this is not an easy tasl<.The difficulties come from trying to model a
`small scale robot after a large—sized one with
`complex shape; something not
`
`easy to reproduce using LEGO parts.
`In this chapter, we describe the clones of two veiy famous robots: R2—D2
`fiom George Lucas’ Star l/Vars saga, probably the most beloved android of all time,
`and Johnny Five/Number Five from John Badhanfs film Short ClI’CI/I2'f.W€ chal-
`lenged ourselves to build both of them using only MINDSTORMS parts, plus
`an optional third motor, with both of them designed for light following, a matter
`not yet explored in the book.As always, you’re invited to use our models as
`starting points for your own variations either in shape or functionality.
`
`if
`
`Building an R2-D2-Style Droid
`
`The “real” R2—D2 is essentially made of a cylindrical body culminating in a
`hemispherical head. Two rigid legs come out from its sides, ending with the
`wheels that provide motion to the robot. R2—D2 is a differential drive. The orig—
`inal character also features a front retractable wheel used only under certain con-
`ditions; in our model this is the third supporting point necessaiy for balance.
`Figure 18.1 shows our R2—D2.You’ll notice it’s more of a symbolic represen-
`tation than a realistic model! The RCX, mounted vertically, constitutes the main
`part of the body, while the head is mimicked by a compound structure of tubes.
`
`
`
`
`
`A
`
`Repiicating Renowned Droids - Chapter 13
`
`351
`
`Figure 18.1 Our R2—D2~Styie Droid
`
`The three motors are behind the RCX (Figures 18.2 and 18.3).Two of them,
`(at the bottom, connect to the Wheels with 21 1:3 ratio,whi1e the third rotates the
`head.As we explained at the begir111ing of the chapter, if you don’t have the third
`motor, you can build a fiXed—he;1d Version of the robot. It, too, will be able to
`follow light.
`
`
`
`
`
`Chapter 18 - Replicating Renowned Droids
`
`Figure 18.2 Front View (with RCX Removed)
`
`352
`
`Each of the drive motors mounts a 24t crown gear, which engages another
`(plain) 24t whose axle ends with an 8t gear. The latter engages a third 24t gear
`connected to the wheel (Figure 18.4).
`The legs are built mainly with plain bricks and 2 X 2 round bricks.They end
`in a 1 x 2 TECI-INIC brick attached to the horizontal beam that locks the upper
`part of the chassis and carries the RCX (see Figure 18.5).The front wheel is a
`simple caster, which is very important for the proper balance of the model.\X/hen
`a robot has a Vertical shape, like R2—D2 has, the position ofits mass is critical for
`its stability during changes of direction and speed. It’s not just a matter of keeping
`the COG inside the supporting base, but mainly of opposing the effect ofinertia,
`which could make your robot flip over (see Chapter 5).
`
`
`
`
`
`
`
`Figure 18.3 Rear View (with RCX Removed)
`
`Repiicating Renowned Droids - Chapter 18
`
`353
`
`
`
`Figure 18.5 Side View
`
`Chapter 18 - Replicating Renowned Droids
`
`354
`
`Looking at the bottom of the robot, you can see the beam that supports the
`pivoting Wheel (Figure 18.6).
`The head mounts a light sensor (Figure 18.7) that you’ll use to locate the
`light source, and gets rotated through a pulley—belt worm—24t gearing system
`(Figure l8.8).This is one of those cases Where pulleys and belts help in transmit-
`ting motion to a distant subsystem. A touch sensor detects the central position of
`the head through the tip ofa cam, With a system similar to the one described in
`Chapter 14 about the steering assembly of a car.
`
`
`
`
`
`
`
`I
`
`Figure 18.6 Bottom View
`
`Repiicating Renowned Droids - Chapter 18
`
`35
`
`
`
`Figure 18.8 The Head Mechanism
`
`356 Chapter 18 - Replicating Renowned Droids
`
`
`
`Programming the Droid
`
`This model of R2—D2 has been conceived as a light follower. The idea is that you
`
`drive it using a source of light, like a flashlight. Though similar to line following
`in some aspects, this task requires a different strategy. The main difference is that
`unlike line following, in which your robot gets consistent readings (that is, the
`light sensor always reads the same values for black or white), when the robot fol-
`
`lows a flashlight beam, the intensity of the driving light will change as the dis—
`tance fioni the source to the robot’s sensor varies.
`
`Thus, you have to differentiate the driving light source from all the other
`
`sources of direct or indirect light in the room.To achieve this, you must scan the
`environment, rotating the head of the robot (or the robot itself) to find the
`strongest Value.Then you will rotate the robot until it finds that intensity again
`(Figure 18.9).
`
`In our first variation in which the robot has a rotating head, the robot is
`stationary; it rotates the head some degrees left, then centers it again at the same
`time reading the light sensors and storing the maximum value into a Variable.The
`following NQC code fragment shows an implementation of the algorithm. It
`assumes that the light sensor is attached to input port 1 and the touch sensor to
`
`
`
`
`
`
`
`Chapter18
`
`35
`
`#define ROTATION__T'IME 50
`
`maxlight_left=O;
`
`OI1Fwd (OUT_B) ;
`
`Wait (ROTATION_TIME) ;
`OnRev(OUT_B) ;
`
`While (SENSOR_3:=O)
`{
`
`light=SENSOR_l;
`
`if (light>maxlight_left)
`{
`
`r
`max1ight_left=light-
`
`light source
`
`
`
`2) come back to
`highest reading
`
`1) locate
`
`strongest source
`
`head of the robot
`
`L Then you repeat exactly the same procedure for the right side, storing the
`m3Ximun1 reading into the /na,\‘lz'g/2f_r1'Lg/zr variable. Now you know VVl1lCl’1 side is
`thé strongest light source, left if l}I(l.X‘/(Lg/lf__/éjfi‘ > Irzax/1'g/zf_;*ig/zr or Vice Versa, and
`_ YOU make the robot turn in place, with its head still and centered, until it finds 21
`
`
`
`
`
` Chapter 18 - Replicating Renowned Droids
`
`similar value. It’s important that your test has some tolerance, as the light intcf
`might have changed a bit from the first moment you read it to the present t
`when you try and aim the robot at it.
`At this point, your robot goes straight for a while, then stops to look for c113
`maximum intensity again and correct its route.
`The variation in which the robot has a fixed head is not too different, just
`.
`change the search procedure to turn the robot in place instead ofits head.You »
`first turn the robot left for a few seconds, then you turn it right for a few second
`
`more while monitoring the readings as in the previous case. The NQC code
`that follows is very similar to the previous example, but uses the drive motors——
`.
`connected to output ports A and C——to make the robot turn. In this case the
`ROTATION_TIl\/LE constant should correspond to the time the robot requires '
`to turn in place at the desired angle:
`
`
`
`#define ROTATIONWTIME 200
`
`maxlight=O;
`
`OnFwd(OUT_A);
`
`OnRev(OUT_C);
`
`Wait(ROTATION~TIMI
`
`LU
`
`‘\
`
`kl
`
`OnRev(OUT_A);
`
`OnFwd(OU”_C);
`
`ClearTimer(l);
`
`while (Timer(1)<ROTATION_TIME)
`
`{
`
`} O
`
`1ight=SENSOR_l;
`
`if (light>maxlight)
`
`{
`
`maxlight=light;
`
`ff(OUT_A+OUT%C)i
`
`When you have determined the maximum reading, rotate the robot until it
`
`reads approximately the same value again.
`
`Acting on the ROT/lTION_TLME constant, you can make your robot
`
`explore all directions 360° around it, or limit its search to a narrower sector.
`
`
`
`
`
`
`
`your robot more toler
`down the Search process.
`In the
`
`adopt a different strategy:
`, one at the corresponding
`ral value is the highest one,
`angle of the route so the
`
`p it for line following you '
`faces down) just behind the pivoting wheel.
`Adding bumpers, on the contrary, is not an easyjob ifyou don’t Want to alter
`the esthetics of the model: R2—D2 ’
`is not Very suitable for cumbe
`By using rotation sensors, you can
`Chapter 4), an appro
`V
`Proximity detection '
`Having extra pieces can niake your R2—
`example, with some plates and l
`'
`18.10), a better approximation to its cylindrical body.
`Figure 18.10 A Section of a Possible Octagonal Body
`
`
`
`
`
` Chapter 18 - Replicating Renowned Droids
`
`.
`
`
`
`You can even remove the pivoting Wheel and make R2—D2 capable of stan
`on two legs by simply placing two aligned wheels into each leg (Figure 18.11).
`Way, the robot is no longer a differential drive and becomes a sl<id—steer drive. To
`use this architecture, it’s Very important you keep the COG (center of gravity) as .
`Close as possible to the ground. Its vertical right should be in the middle of the sup-
`port base, delimited by the four touching points of the wheels in order to reduce 1.
`the tendency of the robot to overturn when starting or stopping.A high reduction.
`ratio between the motors and the wheels helps, too.
`
`Figure 18.11 A Double-Wheeled Leg
`
`
`
`Replicating Renowned Droids ° Chapter 18
`
`361
`
`Building a lohrmy F§ve~Style Droid
`johnny Five (or Number Five) has a much less compact structure than R2—D2. Its
`body is slim and articulated at many points, and the Whole is supported by two
`large tracks. Replicating this in LEGO is quite a challenging task, especially because
`the RCX and the motors are rather large compared to the size of the tracks avail-
`able in the MINDSTORMS kit.Things get better if you scale the model up, but
`you would need many extra parts and, above all, some larger tracks.
`Since We can’t have everything, we decided to be satisfied with just repro-
`ducing some of the main features ofjohnny Five: the triangular tracks, the rear
`pivoting Wheel, a rotating head and two (decorative only) hands (Figure 18.12)
`Figure 18.12 Our Johnny Five—Style Droid
`
`
`
`
`
`362
`
`Chapter 18 - Replicating Renowned Droids
`
`The body ofjohnny Five has been built around a chassis with a triangular
`section. Looking at the robot from its side, you’ll notice that three beams form a
`peifect right triangle with sides of length 6, 8, and 10 (Figure 18.1 3).The vertical
`1 x 16 beam also serves as a support for the upper wheel of the tracks and the 115;;
`ii
`mechanism. Since the MINDSTORMS kit includes only four track wheels, we
`made two more from a pair of pulleys with a bushing in the middle. The pivoting;
`wheel is not actually necessary to support the robot, but it enhances its look.
`
`A
`
`Figure 18.13 Johnny Five Side View
`
`The gearing of the drive motors is rather simple: an 8t gear on the motor
`shaft engages a 24t gear connected to the drive axles. (Remember that you also
`need a l6t gear inside the track wheel to joint it to the axle.)
`The third motor lies on a second layer above the first two, and it’s braced by a
`diagonal beam with a quite unconventional slope: this triangle has a base of 2
`studs, a height of7 1/3 bricks that corresponds to 8.8 studs, and a diagonal of 9
`studs.The match is not perfect, but the error is less than three parts in a thousand
`and gives a solid bracing to the motors without disturbing the pivoting wheel
`
`(Figure 18.14).
`
`
`
`
`
`Figure 18.14 Johnny Five Rear View
`
`Repiicating Renowned Droids ° Chapter 18
`
`363
`
` 2
`
`
`
`,,__,Wm_.w,,.,,w,:,._.-.:,;.t».».h,IA-.:y._L...»{|-»»a~:,u..m:
`
`
`
`V.,,.;¢,,,t...a>.,.,.'ax .
`
`
`
`1
`
`Figure 18.15 shows the bottom of the 1'0bot.You’11 notice that Wejoined the
`front axles together to make them more solid, relying on the fact that the track
`e Whee]s are free to rotate on them. On the other side, the rear track Wheels have
`16t gears‘1'r1sid.e. As explained in the MINDSTORMS Constructopedia, this is
`the Way to securely join them to their axle.
`
`T
`
`L
`_
`
`
`
`
`
`
`364
`
`Chapter 18 - Replicating Renowned Droids
`
`
`
`Figure 18.15 Johnny Five Bottom View
`
`The head mechanism is nearly identical to the one we designed for R2—D2:
`A pulley—belt system rotates a worm gear, which engages a 2-/lt. A cam closes a
`touch sensor when the head is centered (Figure 18.16).
`We got sentimental and rebuilt for johnny Five the same head we designed
`together in 1998 for one of our first MINDSTORIWS projects, called S3 (see
`Figure 18.17).
`
`5%
`
` OTE
`
`Refer to the earlier section on programming the R2-D2-style droid when
`programming the Johnny Five robot—the two models can be driven by
`the same software.
`
`
`
`
`
`
`
`
`
`
`3".
`
`V?
`
`Figure 18.16 The Johnny Five Head Mechanism
`
`Replicating Renowned Droids ° Chapter 18
`
`365
`
`Figure 18.17 CIose—Up of the Head
`
`”§§E»?>3L«1§
`
`
`
` Chapter 18 ° Replicating Renowned Droids
`
`Variations on the Construction
`
`
`
`In introducing this robot, We explained that if you want to make your Version
`more similar to the one from the movie, you have to increase its s<:ale.You wfli
`need some extra parts, but those are easy to find.The greatest problem comes
`from the tracks:You can’t use the ones from the MINDSTORMS kit for a larg
`johnny Five, because they’re too small and will make it look ridiculous. Staying
`with LEGO components you have two alternatives: the Cyberniaster tracks and
`the n1odul9.r chain link tracks (see Chapter 9), both of which are 3 bit hard to
`find.The latter represents :1 very flexible solution that allows you to adjust the
`length of the track precisely to your needs, and it’s What We used for Cinque, the ‘
`larger johnny Five~styled robot described on our site (Figure 18.18).
`A
`
`V
`
`Figure 18.18 Cinque, Our Replica of Johnny Five
`
`
`
`
`
`£»AA).u.A4'n.;...,4.t...;t.u...t1m
`
`
`
`«ummwua.:t..q.:pklAnIo1A—.bl“:--_...t..t.m._‘
`
`
`Replicating Renowned Droids = Chapter 18
`
`357
`
`Ifyou’re open to nonoriginal components, you can search toy shops for
`cheap toy tanks: some of them feature tracks that may be adapted to LEGO and
`might fit your needs Very Well. Usually, you cannot use the standard LEGO track
`Wheels. Instead, you have to build suitable ones combining wheels in pairs with a
`half or whole bushing in the middle (Figure 18.19)
`
`Figure 18.19 Nonoriginal Tracks
`
`
`
`coupied wheeis
`with bed? bushing
`
`
`
`
`
`
`
`
`
`
`358
`
`Chapter 18 - Replicating Renowned Droids
`
`Summary
`
`lfyou decide to reproduce one of the famous robots that populate sci—fi movies,
`you will face difficulties similar to What We described in Chapter 17 about
`making robotic animals: matching the form to the function.
`The process can be made a bit easier by choosing the proper scale for the
`model. Generally speaking, the bigger the size, the better the result, because the
`size of your elements become less relevant when compared to the size of the
`model, allowing you to make finer details. Unfortunately, sizing up is not always
`an option, because you must take into account your own part availability, and the
`size of some special components, like wheels and tracks, that limit the maximum
`dimension you can aspire to.
`On the technical side, both the droids gave you the chance to see some of the
`theoretical concepts of Part I put into practice. For example, the vertical shape of
`R2—D2 requires the thoughtful application of the ideas expressed in Chapter 5
`about balancing the robot to oppose the effects of inertia.The Johnny Five model
`is the first robot of Part II to use the triangular structures described in Chapter 1.
`It is also the first one that uses tracks instead of Wheels, implementing the skid-
`steer drive scheme described in Chapter 8.To make its tracks outline a triangular
`shape, We had to build a third pair of tracl<—vvheels; this is a good example of the
`powerful modularity of the LEGO system, which allows you to replicate the
`functionality of one part by using other basic elements.
`This chapter also introduced you to a programming challenge we haven’t
`discussed yet: light following. It has significant differences from line following,
`because you cannot rely on the constant readings that come from a black and
`white pad. Instead, you have to scan the environment looking for the strongest
`light source, and then follow that direction. For line following, we suggested a
`
`e
`
`i
`
`
`
`
`
`Replicating Renowned Droids ° Chapter 13
`
`369
`
`calibration procedure be executed before running the robot along the line in
`order to evaluate the Il’13XLl1"I1ll1’I1 and minimum values the robot should €XpeCt_ In
`the case of light following, this kind of procedure is performed every time the
`robot Wants to decide in which direction it should go.
`We invite you to Visit some of the Web sites listed in Appendix A. Most of
`them will be of great inspiration when it comes to making your own droids.
`
`l1JI
`31
`
`l
Accessing this document will incur an additional charge of $.
After purchase, you can access this document again without charge.
Accept $ Charge
Still Working On It
This document is taking longer than usual to download. This can happen if we need to contact the court directly to obtain the document and their servers are running slowly.
Give it another minute or two to complete, and then try the refresh button.
A few More Minutes ... Still Working
It can take up to 5 minutes for us to download a document if the court servers are running slowly.
Thank you for your continued patience.
This document could not be displayed.
We could not find this document within its docket. Please go back to the docket page and check the link. If that does not work, go back to the docket and refresh it to pull the newest information.
Your account does not support viewing this document.
You need a Paid Account to view this document. Click here to change your account type.
Your account does not support viewing this document.
Set your membership
status to view this document.
With a Docket Alarm membership, you'll
get a whole lot more, including:
- Up-to-date information for this case.
- Email alerts whenever there is an update.
- Full text search for other cases.
- Get email alerts whenever a new case matches your search.
One Moment Please
The filing “” is large (MB) and is being downloaded.
Please refresh this page in a few minutes to see if the filing has been downloaded. The filing will also be emailed to you when the download completes.
Your document is on its way!
If you do not receive the document in five minutes, contact support at support@docketalarm.com.
Sealed Document
We are unable to display this document, it may be under a court ordered seal.
If you have proper credentials to access the file, you may proceed directly to the court's system using your government issued username and password.
Access Government Site
