202 Chapter 9 n Go Bot. Hint

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1 Chapter 9 Go Bot Now it s time to put everythig you have leared so far i this book to good use. I this chapter you will lear how to create your first robotic project, the Go Bot, a four-wheeled robot. It uses two servo motors to drive it. It will be programmed to move forward ad backward, talk, ad display friedly text messages. Go Bot is a great first robotic developmet project, providig a effective example of the fudametal steps ivolved i robotic developmet. It will also provide you with the opportuity to put your programmig skills to good use. The major topics covered i this chapter iclude: Developig a basic uderstadig of how to create modular robots. A review of Go Bot s features ad capabilities. Step-by-step istructios for buildig Go Bot. Learig how to remote cotrol Go Bot. A complete review of the NXT-G program that makes Go Bot come to life. 201

2 202 Chapter 9 Go Bot Robotic Developmet Methodology Robotic developmet is usually completed through a series of steps, begiig with desig, the assembly, ad, fially, programmig ad testig. I each chapter that follows, you will be preseted with a brief itroductio that provides a high-level overview ad desig of a differet robot. More ofte tha ot, developmet ivolves a lot of experimetatio ad plety of mistakes, correctios, ad modificatios. As you work, make sure that you build structures that are strog ad fuctioal. I additio, approach developmet i a modular maer by breakig dow your robots ito a series of distict subassemblies that, whe put together, make up your robot. Oce assembly is completed, you will wrap thigs up by programmig ad the testig your robot. Hit Whe you re doe with a robot that you are proud of, it s a good idea to documet what you have accomplished. This ca be doe as easily as sappig a picture of your robot, or it ca be as complex as developig a complete set of build istructios, which you ca create usig various CAD programs like the Lego Digital Desiger or LDRAW. You might eve cosider creatig a video of your robot s assembly ad operatio. Itroducig Go Bot Movig vehicles are a popular type of robot ad make for a excellet startig poit. Go Bot is such a robot. As show i Figure 9.1, Go Bot is a four-wheeled robotic vehicle. The two frot wheels are coected to ad operated by servo motors ad are resposible for the vehicle s propulsio. The back two wheels provide additioal support. Go Bot will be programmed to begi by sayig ad displayig the word Hello o the NXT Brick s LCD. Next it will play a toe, move forward, pause, ad play aother toe. Go Bot will the move backward to its startig poit, play a toe, ad spi i place before sayig Goodbye ad haltig. Hit The Go Bot ca be used as the basis for creatig all sorts of other vehicles. It will serve as the startig poit for the robotic projects i Chapters 10 ad 11.

3 Buildig Go Bot 203 Figure 9.1 The Go Bot is a four-wheeled robotic vehicle. Buildig Go Bot Go Bot is a relatively simple ad straightforward robotic project. You will create it i six high level steps as outlied below. Preparig the NXT Brick Assemblig the left motor drive Assemblig the right motor drive Assemblig the rear wheel chassis Assemblig Go Bot Programmig ad testig Go Bot Figure 9.2 provides a complete listig of all the differet electroic compoets ad parts eeded to make Go Bot. Begi your work o this project by retrievig these pieces from your Lego Midstorms NXT 2.0 kit ad settig them aside to work with.

4 204 Chapter 9 Go Bot Figure 9.2 The parts ivetory list for Go Bot. Preparig the NXT Brick Begi the developmet of Go Bot by preparig the NXT Brick. This ivolves the attachmet of several pieces to the NXT Brick. This facilitates the coectio of the servo motor assemblies that will be created i Steps 2 ad 3 ad the added to the NXT Brick i Step 5.

5 Buildig Go Bot 205 Step 1 Take two 5M straight beams, four coector peg with frictio 3M pegs, ad two 3 5M perpedicular beams ad coect them as show i Figure 9.3. Figure 9.3 Step 2 Take the compoets created i Step 1 ad coect them to the NXT Brick as show i Figure 9.4. Figure 9.4 Assemblig the Left Motor Drive Now it is time to begi workig o Go Bot s servo drive assemblies, begiig with the left motor drive. This is accomplished i four steps.

6 206 Chapter 9 Go Bot Step 1 Create the robot s left wheel by coectig a rim to a tire as show i Figure 9.5. Figure 9.5 Step 2 Coect oe coector peg with frictio ad cross axles ad six coector pegs with frictio to oe of the servo motors as show i Figure 9.6. Figure 9.6 Step 3 Coect the completed wheel to the servo motor usig oe 7M cross axle ad two bushigs as show i Figure 9.7.

7 Buildig Go Bot 207 Figure 9.7 Step 4 Coect two coector pegs with frictio to a 3 7 double broke agle beam, as show i Figure 9.8, ad the coect the double broke agle beam to the servo motor as also show i Figure 9.8. Figure 9.8 Hit The completed left motor drive should look like the example show i Figure 9.9. Figure 9.9

8 208 Chapter 9 Go Bot Assemblig the Right Motor Drive The steps required to create the right motor drive assembly closely mirror the steps that you followed to assemble the left motor assembly ad are accomplished i four steps. Step 1 Create the robot s right wheel by coectig a rim to a tire as show i Figure Figure 9.10 Step 2 Coect oe coector peg with frictio ad cross axles ad six coector pegs with frictio to oe of the robot s servo motors as show i Figure Figure 9.11

9 Buildig Go Bot 209 Step 3 Coect the completed wheel to the servo motor usig oe 7M cross axle ad two bushigs as show i Figure Figure 9.12 Step 4 Coect two coector pegs with frictio to a 3 7 double broke agle beam, as show i Figure 9.13, ad the coect the double broke agle beam to the servo motor, as also show i Figure Figure 9.13 Hit The completed right motor drive should look like the example show i Figure 9.14.

10 210 Chapter 9 Go Bot Figure 9.14 Assemblig the Rear Wheel Chassis With the NXT Brick ow prepared ad the Go Bot s left ad right servo motor assemblies complete, it s time to create the robot s rear wheel chassis. This will be accomplished i four steps. Step 1 Coect two 15M straight beams ad two 3 7 agle beams usig four pegged perpedicular block 5M pieces as show i Figure Make sure that whe coectig the pegged perpedicular block 5M pieces to the 15M straight beams that you isert the peg eds of the pegged perpedicular block 5M pieces ito the first ad third holes o each ed of the 15M straight beam. Figure 9.15

11 Buildig Go Bot 211 Step 2 Coect two 3 5M perpedicular beams to the upper left ad right eds of the chassis usig a coector peg with frictio ad coector peg with frictio ad cross axle, as show i Figure Figure 9.16 Step 3 Coect a 3M straight beam to the left side of the rear chassis usig a coector peg with frictio ad coector peg with frictio ad cross axle, as show i Figure Add a secod 3M straight beam to the right side of the rear chassis usig a secod coector peg with frictio ad coector peg with frictio ad cross axle (ot show i Figure 9.17). Figure 9.17 Step 4 Assemble a ew wheel usig a rim ad tire ad add the wheel to the rear chassis usig a 5M cross axle, two bushigs, ad two half-bushigs as show i Figure 9.18.

12 212 Chapter 9 Go Bot Figure 9.18 Hit The completed rear wheel chassis should look like the example show i Figure Figure 9.19 Assemblig Go Bot Now that all of the major subassemblies that make up Go Bot have bee put together, it is time to assemble these subassemblies ito a completed robot. Step 1 Attach the left ad right servo motor assemblies to the NXT Brick, as show i Figure 9.20.

13 Buildig Go Bot 213 Figure 9.20 Step 2 As show i Figure 9.21, coect the robot s rear wheel chassis to the robot by coectig its 3 5M perpedicular beam to the left ad right servo motors usig the two sets of coector pegs with frictio that are already coected to the servo motors. Figure 9.21

14 214 Chapter 9 Go Bot Hit A fully assembled copy of Go Bot is show i Figure Figure 9.22 Step 3 To operate, the robot s two servo motors must be coected to the NXT Brick. Set this up by coectig the left servo motor to the NXT Brick s C port ad the right servo motor to the NXT Brick s B port usig a pair of 35cm/ 14-ich cables, as show i Figure Figure 9.23

15 Buildig Go Bot 215 Programmig Go Bot Now that Go Bot has bee assembled, it is time to begi work o the NXT-G program that will brig it to life. The NXT-G program itself will be relatively simple. It will provide istructios to the Go Bot to perform the followig actios: Drive forward Drive backward Spi i place Talk Display differet text messages The NXT-G program will be created i three distict stages. I the first stage, the programmig blocks eeded to cotrol the robot s movemet will be added to the program ad cofigured. The robot s operatio will the be tested to esure that thigs work as they should. Next, Soud ad Display blocks will be added to the NXT-G program to give the robot some persoality. This will complete the developmet of the robot s programmig. The robot s operatios will agai be tested. Lastly, you will add commets to the NXT-G program that documet its operatio, ad the you will perform oe last test of the robot s operatios. Stage 1 Movig the Robot Begi the developmet of Go Bot s NXT-G program by creatig a ew NXT-G program amed Go_Bot. Oce created, drag ad drop three istaces of the Move block oto the program s mai sequece beam. The first Move block will be resposible for movig the robot forward i a straight lie. Select it ad cofigure it as follows: Port Select ports B ad C. Directio Select Forward. Steerig Make sure the slide is cetered i the middle of the slider bar, cofigurig the robot to move forward i a straight lie. Power Set power to 75 percet.

16 216 Chapter 9 Go Bot Duratio Set duratio to 5 secods. Next Actio Select Brake. The secod Move block will move the robot backward i a straight lie to its origial startig positio. Select it ad cofigure it as follows: Port Select ports B ad C. Directio Select Backward. Steerig Make sure the slide is cetered i the middle of the slider bar, cofigurig the robot to move backward i a straight lie. Power Set power to 75 percet. Duratio Set duratio to 5 secods. Next Actio Select Brake. The third Move block will be used to spi the robot full circle, pivotig it alog its left frot wheel (which is coected to Port C). Select the third Move block ad cofigure it as follows: Port Select port C. Directio Select Forward. Steerig N/A. Power Set power to 75 percet. Duratio Set duratio to 2900 degrees. Next Actio Select Brake. Figure 9.24 shows how the NXT-G program should look at this poit. Save the program ad the tur o ad coect the robot (e.g. NXT Brick) to your computer ad dowload the program by clickig o the NXT Dowload butto located at the bottom right corer of the work area. Oce the NXT-G program has bee dowloaded, discoect Go Bot ad place it o the floor i a area free of obstacles. Press the NXT Brick s orage butto four times to select ad ru the NXT-G program. Esure that, oce started, the Go Bot moves forward ad backward ad that it the spis i place. If it does ot perform all of these tasks correctly, go back ad

17 Buildig Go Bot 217 Figure 9.24 A simple startig versio of the Go Bot s NXT-G program. review each of the programmig blocks that make up the NXT-G program ad esure that their cofiguratio matches up with the cofiguratio settigs specified for each block. Oce you have foud ad corrected ay block cofiguratio errors, dowload ad retest Go Bot s operatio before proceedig to the secod stage of the program s developmet. Stage 2 Gettig the Robot to Speak ad Display Text Now that Go Bot s base fuctioality has bee programmed ad validated, it s time to provide the robot with a little persoality through the additio ad cofiguratio of Soud, Display, ad Wait Sesor programmig blocks that together eable the robot to: Say Hello whe first started. Display the text strig Hi. I am Go Bot! o the NXT Brick s LCD. Pause for two secods. Play a toe before ad after each movemet made by Go Bot. Say Goodbye. Display the text strig Goodbye o the NXT Brick s LCD. Begi by isertig a Soud block o the sequece beam immediately before the first of the three Move blocks. Select the Soud block ad cofigure it as follows: Actio Select Soud File. Cotrol Select Play. Volume Set value level to 75 percet.

18 218 Chapter 9 Go Bot Fuctio Esure that Repeat is ot selected. File Select Hello from the list of files i the scrollig list box. Wait Select Wait for Completio. Isert a Display block betwee the Soud block ad the first of the three Move blocks. Select the Display block ad cofigure it as follows: Actio Select Text from the drop-dow list. Display Select Clear. Text Type Hi. I am Go Bot! i the text etry field. Positio Specify a value of 3 for X ad 26 for Y. Isert a Sesor Wait block i betwee the Display block ad the first of the three Move blocks. Select the Sesor block ad cofigure it as follows: Cotrol Select Time from the drop-dow list. Util Type a value of 2 i the Secods etry field. Isert a Soud block betwee the Sesor Time block ad the first of the three Move blocks. Select the Soud block ad cofigure it as follows: Actio Select Toe. Cotrol Select Play. Volume Set value level to 75 percet. Fuctio Esure that Repeat is ot selected. Note Specify a ote value of C ad set it to play for.5 secods. Wait Select Wait for Completio. Isert a ew Soud block just after the first of the three Move blocks. Select the Soud block ad cofigure it exactly the same way as you did the previous Soud block. Isert aother Soud block just after the secod of the three Move blocks. Select the Soud block ad cofigure it exactly the same way as you did the two previous Soud blocks.

19 Buildig Go Bot 219 Isert aother Soud block just after the third of the three Move blocks. Select the Soud block ad cofigure it as follows: Actio Select Soud File. Cotrol Select Play. Volume Set value level to 75 percet. Fuctio Esure that Repeat is ot selected. File Select Goodbye from the list of files i the scrollig list box. Wait Select Wait for Completio. Next, add a Display block to the ed of the sequece beam ad cofigure it as follows: Actio Select Text from the drop-dow list. Display Select Clear. Text Type Goodbye i the text etry field. Positio Specify a value of 30 for X ad 29 for Y. Lastly, add a Sesor Wait block at the ed of the sequece beam. Select the Sesor block ad cofigure it as follows: Cotrol Select Time from the drop-dow list. Util Type a value of 1 i the Secods etry field. Figure 9.25 shows how the NXT-G program should ow look. Save the program ad the tur o ad coect the robot (e.g. NXT Brick) to your computer ad dowload the program by clickig o the NXT Dowload butto located at the bottom right corer of the work area. Oce the NXT-G program has bee dowloaded, discoect Go Bot ad place it o the floor i a area free of Figure 9.25 This versio of the Go_Bot NXT-G program cotais all of the robot s programmig logic.

20 220 Chapter 9 Go Bot obstacles. Press o the NXT Brick s orage butto four times to select ad ru the NXT-G program. Before cotiuig to the fial stage of the NXT-G program s developmet, test the robot ad make sure it operates as previously described. Stage 3 Documet the NXT-G Program At this poit Go Bot s NXT-G program is almost doe. All that remais is for you to documet its operatio. Update the Go_Bot program so that it cotais all of the commets show i Figure Cogratulatios o the creatio of your very first robot. This is a cosiderable achievemet. Before movig o to Chapter 10, Tracker Bot, to lear how to further ehace the robot, take a few miutes to fully test the operatio of Go Bot, esurig that it works as described. If it does ot perform exactly as has bee described, go back ad review each of the programmig blocks that make up the NXT-G program ad esure that their cofiguratio matches up correctly with the cofiguratio settigs that were previously specified for each block. Figure 9.26 The fial versio of the Go_Bot NXT-G program.

21 Remote Cotrollig Go Bot 221 Remote Cotrollig Go Bot As a movig robot, Go Bot s movemet ca be cotrolled via NXT-G programs that you develop ad dowload ito the NXT Brick. Alteratively, you ca use the Remote Cotrol widow to cotrol Go Bot with your mouse or keyboard. To access the Remote Cotrol widow, show i Figure 9.27, click o Tools > Remote Cotrol. Hit I order to be able to make effective use of the Remote Cotrol feature, you either eed a relatively log USB cable or a wireless Bluetooth coectio. For the remote cotrol to work, the NXT Brick must be powered o ad a coectio must exist betwee the robot (e.g. NXT Brick) ad your computer. Otherwise, the Remote Cotrol widow will appear grayed out ad you will ot be able to access ay of the cotrols show o it. Ofte, Lego Midstorms NXT 2.0 automatically detects ad establishes a coectio with the NXT Brick. However, sometimes you may have to do it yourself. To do so, click o the Coectios butto ad the select your NXT Brick ad click o the Coectios butto followed by the Close butto. With a coectio established, use your mousetoclickotheforward,backward, Left, ad Right butto to remotely cotrol the movemet of Go Bot. Alteratively, Figure 9.27 Usig the Remote Cotrol widow to operate Go Bot.

22 222 Chapter 9 Go Bot you ca use the keyboard s Up, Dow, Right, ad Left keys to cotrol Go Bot s movemet. You ca adjust the speed at which Go Bot moves by clickig o either the Icrease Speed or Decrease Speed buttos or by clickig directly o the graphic speed meter to idicate the speed at which you wat Go Bot to move. Summary This chapter showed you how to create your first robotic creatio, Go Bot. I developig Go Bot, you leared the fudametal steps ivolved i robotic developmet: desig, build, program, ad test. This chapter explaied the importace of breakig dow robot developmet ito subassemblies. You also leared how to develop Go Bot s NXT-G program i several stages, testig the robot s operatio at the ed of each stage. Fially, you leared how to use the Remote Cotrol widow to maually take cotrol of Go Bot.