HexCrawler Kit Assembly, Tuning and Example Program

Transcription

1 HexCrawler Kit Assembly, Tuning and Example Program VERSION 1.2

2 WARRANTY Parallax warrants its products against defects in materials and workmanship for a period of 90 days. If you discover a defect, Parallax will, at its option, repair, replace, or refund the purchase price. Simply call for a Return Merchandise Authorization (RMA) number, write the number on the outside of the box and send it back to Parallax. Please include your name, telephone number, shipping address, and a description of the problem. We will return your product, or its replacement, using the same shipping method used to ship the product to Parallax. 14-DAY MONEY BACK GUARANTEE If, within 14 days of having received your product, you find that it does not suit your needs, you may return it for a full refund. Parallax will refund the purchase price of the product, excluding shipping / handling costs. This does not apply if the product has been altered or damaged. COPYRIGHTS AND TRADEMARKS This documentation is copyright 2004 by Parallax, Inc. BASIC Stamp is a registered trademark of Parallax, Inc. If you decided to use the name BASIC Stamp on your web page or in printed material, you must state that "BASIC Stamp is a registered trademark of Parallax, Inc." Other brand and product names are trademarks or registered trademarks of their respective holders. DISCLAIMER OF LIABILITY Parallax, Inc. is not responsible for special, incidental, or consequential damages resulting from any breach of warranty, or under any legal theory, including lost profits, downtime, goodwill, damage to or replacement of equipment or property, and any costs or recovering, reprogramming, or reproducing any data stored in or used with Parallax products. Parallax is also not responsible for any personal damage, including that to life and health, resulting from use of any of our products. You take full responsibility for your BASIC Stamp application, no matter how life-threatening it may be. INTERNET ACCESS We maintain internet systems for your use. These may be used to obtain software, communicate with members of Parallax, and communicate with other customers. Access information is shown below: info@parallax.com Web: INTERNET BASIC STAMP DISCUSSION LIST We maintain two discussion lists for people interested in BASIC Stamps (subscribe at under the technical support button). The BASIC Stamp list server includes engineers, hobbyists, and enthusiasts. The list works like this: lots of people subscribe to the list, and then all questions and answers to the list are distributed to all subscribers. It s a fun, fast, and free way to discuss BASIC Stamp issues and get answers to technical questions. This list generates about 40 messages per day. The Stamps in Class list is for students and educators who wish to share educational ideas. To subscribe to this list go to and look for the E- groups list. This list generates about 5 messages per day.

3 Table of Contents Page i Table of Contents Preface... iii Chapter #1: Preparing to Assemble the Hexcrawler... 1 Required Tools... 1 Hexcrawler Full Kit Inventory (#30063)... 1 Electronics... 1 Aluminum Parts... 1 Nuts, Bolts and Screws... 2 Miscellaneous... 2 From the Parallax Web Site ( Additional Parts You Need to Acquire... 4 Chapter #2: Pre-Assembly Tips... 5 Pay Attention to Details... 5 Preparing the Servos... 6 Chapter #3: Hexcrawler Assembly... 7 Mounting the Servos... 7 Assembling the Lower Leg and Attaching it to the Upper Leg Assembly Top Servo Installation Leg Pivot Installation Preparing the HexCrawler s Upper Deck Installing the Side Supports Installing the Front and Rear Supports Installing the Leg Assemblies to the Upper Deck Preparing the Lower Deck Attaching the Upper Deck Assembly to the Lower Deck Assembly Installing the Chapter #4: Wiring and Tuning the HexCrawler Connecting the SSCII to the Leg Servos Connecting the SSCII to the Leg Servos Connecting the Leg Servos and SSCIIs Connecting the SSCIIs Serial In to the BOE Assembling the Seven-Segment LED Control System SSCII SVO Power Connections Chapter #5: Program the HexCrawler Testing the Pushbutton Controls Testing the Seven Segment LED Tuning the HexCrawler s Legs Download and Running the Home Program Adjusting the HexCrawler s Legs Horizontal Servo Adjustment Vertical Servo Adjustment Running the Walking Programs Ripple Gait Overview Tri-Pod Gait Overview... 82

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5 Preface Page iii Preface The HexCrawler is an original design from Alex Dirks of CrustCrawler ( Parallax is the exclusive distributor and final kit assembler of the product. Parallax has taken many efforts to ensure that the kit includes only the highest quality metal parts, electronics and instructions to ensure that you get the HexCrawler operating correctly. If you are not having success with the kits or just have some feedback, send it to us. The HexCrawler hexapod is an advanced robotic kit consisting of a walking platform. Unlike other Parallax robotic kits, this kit does not include a series of step-by-step educational projects for the HexCrawler. Essentially, the kit is a platform for your additional robotic projects. The applications Parallax provides on our HexCrawler web pages are project-oriented. For example, in October we completed an application with a video camera and remote control for telerobotic applications. This application is available for download. Experience programming the BASIC Stamp is helpful, but if you need more help in this regard you can find plenty of robotic programming resources on the Parallax web site. All of the sensors we sell include BASIC Stamp program examples which you could readily adapt to the HexCrawler. Building the HexCrawler also requires working with hand tools and a soldering iron. The extent of soldering is quite minimal and likely applies only to the wiring harness for the power supply. The power supply requires connecting the 7.2 V batteries to the SSC2 power supply and the possible construction of a wiring harness unless with a toggle switch (provided by you) unless you decide to use the Board of Education s breadboard space for power supply connections. Putting the hardware together also requires some skill with hand tools. If you are not semi-skilled with common hand tools and are not willing to use a soldering iron we recommend you return the kit prior to assembly unless you have some patience. But, the Parallax team assures you that if you can successfully complete the HexCrawler you re in for an exciting series of robotic projects that you will find highly rewarding. Our office staff has taken to the HexCrawler by customizing it with unique paint jobs, cameras and ultrasonic sensors.

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7 Chapter 1: Preparing to Assemble the HexCrawler Page 1 Chapter #1: Preparing to Assemble the HexCrawler REQUIRED TOOLS The following tools will be required to build your HexCrawler: Phillips screwdriver Flat head screwdriver Drill 7/64 drill bit Small adjustable crescent wrench or socket set Clear Liquid Nails glue for small projects (we recommend Perfect Glue #2 from Home Depot) Wire cutters A small amount of white grease or equivalent HEXCRAWLER FULL KIT INVENTORY (#30063) The HexCrawler Complete Kit (#30063) contains the following components: Electronics: (1) BASIC Stamp 2 Module (1) Board of Education (12) Parallax standard servos (1) Serial Cable (1) Parallax CD-ROM (2) Mini SSC IIs (Scott Edwards Electronics) (1) Seven-segment LED (green) (2) 220 ohm resistors (red, red, brown) (7) 1K ohm resistors (red, black, brown) (2) 10K ohm resistors (brown, black, orange) (2) pushbutton (1) package 3 jumper wires Aluminum Parts: (1) upper main body deck (1) lower main body deck (2) square front and rear support braces (4) side braces (12) leg mounts (12) lower, horizontal leg braces (12) vertical leg braces (6) leg actuators (6) leg actuator supports

8 Page 2 HexCrawler Kit (6) servo mounts (6) servo blanks Nuts, Bolts, Washers and Screws (18) #2 nuts (18) #2 lock washers (24) #2 washers (80) #4 washers (12) #4 5/8 screws (24) # screws (36) #4 3/8 screws (6) #4 ¼ screws (24) #4 nuts (24) #4 lock nuts (24) #4 lock washers (24) #6 3/8 screws (24) #6 lock nuts (84) #8 flat washers (6) #8 1 screws (30) #8 lock nuts (24) # screws (12) #8 ½ nylon spacers (30) #8 ¼ nylon spacers (60) #8 flat nylong spacers Miscellaneous HexCrawler Manual (6)- ¾ long - 2/56 threaded rods (6) rubber feet (12) dog bones (12) ball links (6) brass couplers (6) 3/8 leg pivots (10) cable ties

9 Chapter 1: Preparing to Assemble the HexCrawler Page 3 Source Code from the Parallax Web Site ( HexCrawler Source Code The Parallax web site HexCrawler page contains sample BS2-IC source code, this installation guide and additional pictures of the HexCrawler to aid you during the construction process. Additionally, we frequently post additional applications for our products on the web site. For example, in October 2003 we posted a HexCrawler application with a video camera and remote control. The Parallax CD-ROM includes the BASIC Stamp Manual and many valuable resources to assist you with your BASIC Stamp programming efforts.

10 Page 4 HexCrawler Kit ADDITIONAL PARTS YOU NEED TO SUPPLY Like other hobby kits, completing the HexCrawler kits requires additional parts that you will need to supply. This hardware is not included in the Parallax kits because it would only drive the cost higher as most of these items are readily available at hobby stores or (purchasing them from Parallax, if available, would probably have a higher price). 7.2 V NiMH or NiCd six-cell rechargeable battery for servo power. This is a standard 1800 mah to 3000 mah battery pack, commonly used in R/C cars. A good source for this product is Tower Hobbies ( Expect to pay between $30 and $60. Or, you can go to Radio Shack who also sells good quality 7.2V NiMH batteries and chargers. AC/DC Digital Peak Charger for the 7.2 V NiCd/NiMH battery. One acceptable product is the Piranha Digital Charger from Tower Hobbies (their stock code #LXCLD5). Probably around $50 or less. Radio Shack also sells chargers for their R/C cars. Zip-ties of the smaller sizes are very useful for securing wires in a tidy fashion. Approximate cost is probably a few dollars. Available from any hardware store. Solder, iron, flux Arranging the power supply on the HexCrawler requires some attention to wiring and making good contacts. The first time you are ready to run your HexCrawler it will not work perhaps due to poor wiring connections. The Mini SSC2s have male posts and you will need to connect your wires to these posts. This requires the use of solder, a soldering iron and flux unless you have female/male jumpers. Approximate cost for soldering tools start at $30 and have no upper limit. Robot sensors The HexCrawler is a platform and the opportunities for sensor integration are endless. Selecting the appropriate sensor is left up to you, our customer. Parallax and CrustCrawler ( have many acceptable add-ons for the CrustCrawler. There is no cost limit in this regard.

11 Chapter 2: Pre-Assembly Tips Page 5 Chapter #2: Pre-Assembly Tips PAY ATTENTION TO DETAILS Work in a well lit, clean environment with lots of workspace Obtain a small stack of books that are approximately the length and width of the HexCrawler s lower deck and is approximately 3.5 to 4 tall when stacked. The added height will be required when attaching the lower and upper decks together. Organize your nuts, bolts and screws so that you have each specific size of lock-nuts, screws, washers in the same group and are easily within reach. Take your time! The HexCrawler kit is a precision made product that contains a lot of parts and requires all parts to be assembled in the exact order as described in this installation manual. The average time to construct a kit is between 8 to 16 hrs. Additional pictures of the construction process may be downloaded from the Parallax web site s HexCrawler pages. During the construction process, please refer to these pictures and the ones in this guide frequently as a reference ( Refer to and study the pictures and close-up diagrams carefully before starting the construction of any part of your kit. Always note the orientation and direction of screws and aluminum parts and which side of your HexCrawler you are constructing! It absolutely makes a difference!

12 Page 6 HexCrawler Kit PREPARING THE SERVOS Remove the aluminum body parts from their protective bags and lay them loosely in their respective groups on your work surface. Gather (6) of the servos and cut the entire screw tab guide off of the GEAR SIDE of the servo only (Figure #1). Remove the servo horn and screw, setting them aside in a safe place. Finished servo has no tab on the gear side. Figure 1: Cutting the Gear-Side Servo Tab Off (6) Servos

13 Chapter 3: HexCrawler Assembly Page 7 Chapter #3: HexCrawler Assembly MOUNTING THE SERVOS Figure 2: Mounting Servos 1. From the remaining (6) uncut servos, remove the stock round servo arm and file the small tab on top of the mounting tabs between the mounting holes on each side so it is flush from the servo. Install the servo into the rectangular portion of the servo mount. The servo gear head should be orientated towards the straight end of the servo mount (Figures 2, 3 and 4) 2. Figure 3 displays the orientation of the servo to the servo mount for the (3) legs on the left side of the HexCrawler and Figure 4 for the (3) legs on the right side of the HexCrawler.

14 Page 8 HexCrawler Kit 3. Using (4) #6-3/8 screws and lock nuts, install the servo to the aluminum servo assembly. The screws heads should be on the plastic servo screw tab side and the lock nuts should be on the servo gear-head side. Complete this step for all (6) legs of your HexCrawler. Figure 3: Servo Orientation Left Legs

15 Figure 4: Servo Orientation Right Legs Chapter 3: HexCrawler Assembly Page 9

16 Page 10 HexCrawler Kit 4. Install the Du-Bro 2-56 threaded ball link to all (6) of the main leg actuators as shown in Figure 5 below. Ensure that the ball link is centered in the slot. Figure 5: Leg Actuator Assembly 5. Steps 6-14 should be performed for each leg in your kit. Once one leg has been assembled, use the finished leg as a quick reference for the assembly of the rest of the legs. 6. Using (1) #8, 1.25 screw, install the leg actuator to the leg actuator support through the #8 hole near the top of the servo mount as shown in Figure 6. Use the same hole for the right and left leg assemblies.

17 Figure 6: Leg Actuator Assembly Chapter 3: HexCrawler Assembly Page 11

18 Page 12 HexCrawler Kit Figure 7: Leg Actuator Note: When mounting the Leg actuator in Figure 7, ensure that the horizontal slot is oriented upwards and is aligned over the servo gear head. Figure 8: Leg Actuator Support Note: The leg actuator support has 3 holes. 2 out of the 3 holes are slightly closer to each other. Be sure to use the hole on the end of the support that is closest to the center hole as shown in Figure 8.

19 Chapter 3: HexCrawler Assembly Page Use the close-up diagram in Figure 9 for the complete assembly sequence. Figure 9: Leg Actuator Assembly 1 - # Screw 6- ¼ nylon spacer 11- Actuator support 2 #8 Stainless steel washer 7 Stainless steel washer 12 Stainless steel washer 3 Leg Actuator 8 Nylon flat spacer 13 Lock nut 4 Nylon flat spacer 9 Servo mount 5 Stainless steel washer 10 - ¼ nylon spacer

20 Page 14 HexCrawler Kit 8. At this point in the process, the leg assembly should look like Figure 10. Note the location and orientation of the holes and ball socket slot. Tighten the screw and lock nut just enough so that the 2 pieces can be easily moved by hand but rigid enough to stand on their own. Do not over-tighten the screws as it makes the rest of the leg assembly difficult to complete. Figure 10: Leg Assembly

21 Chapter 3: HexCrawler Assembly Page Attach (2) lower horizontal leg braces with the same hardware and in the same order as the previous steps to the lower hole on the servo mount as shown in Figure 11. Use the close-up diagram on the next page as a reference. Figure 11: Lower Horizontal Leg Brace

22 Page 16 HexCrawler Kit Figure 12: Lower Horizontal Leg Assembly 1 - #8 Screw 1-1/4 6- ¼ Nylon spacer 11- Lower horizontal leg brace 2 Stainless steel washer 7 Stainless steel washer 12 Stainless steel washer 3 Lower horizontal leg brace 8 - Nylon flat spacer 13 - Lock nut 4 - Nylon flat spacer 9 Servo Mount 5 Stainless steel washer 10 - ¼ Nylon spacer

23 Chapter 3: HexCrawler Assembly Page 17 When completed, the leg assembly should look like Figure 13. Figure 13: Completed Leg Assembly 10. Next, install the 2 vertical leg braces (Figure 14) to the leg assembly. Use Figure 15 to assemble the vertical leg braces. Figure 14: Vertical Leg Brace

24 Page 18 HexCrawler Kit Figure 15: Vertical Leg Assembly 1 - #8 1 1/4 screw 7 - Vertical leg brace 2 - Stainless flat washer 8 - Flat nylon spacer 3 - Lower horizontal leg brace 9 - Lower horizontal leg brace 4 - Flat nylon spacer 10 - Stainless flat washer 5 - Vertical leg brace 11 - Lock nut 6 - ½ nylon spacer

25 Chapter 3: HexCrawler Assembly Page 19 Tip Assemble the top of the vertical leg brace assembly first and then assemble the lower vertical leg assembly. As shown in the close-up view above, the assembly sequence and parts are identical. Do not completely tighten the upper or the lower #8 screws. Leave the screws just loose enough so that the leg assembly can be moved up and down easily by hand. When completed, the leg assembly should look like Figure 16. Figure 16: Completed Leg Assembly

26 Page 20 HexCrawler Kit ASSEMBLING THE LOWER LEG AND ATTACHING IT TO UPPER LEG ASSEMBLY 11. Assemble the lower leg assembly first (using parts 1 7) and then attach the lower leg assembly to the upper leg assembly (using parts 8 16) as shown in Figure 17. Figure #4 5/8 screw 5- Aluminum leg mount 9- Stainless washer 13- Nylon flat spacer 2- #4 Stainless washer 6- Stainless washer 10- Vertical leg mount 14- Vertical leg mount 3- Aluminum leg mount 7- Lock nut 11- Nylon flat spacer 15- Stainless washer 4- Plastic leg 8 - #8 1 stainless screw washer 12- ¼ nylon flat spacer 16- Lock nut

27 Chapter 3: HexCrawler Assembly Page 21 When completed, the leg assembly should look like Figure 18. Figure 18

28 Page 22 HexCrawler Kit TOP SERVO INSTALLATION 12. Mount the modified servo (with the single screw tab cut off) to the top of the servo mount with the gear head orientated towards the sloping side of the servo mount using the (4) holes in the servo mount shown in Figure 19. Use (4) # screws, lock nuts and washers to secure it to the horizontal servo blank. Refer to Figure 20 as a reference. Screw the (4) #4 screws completely through the servo blanks first as it will make mounting the servo easier. Ensure that the top servo sits evenly on the lower servo before tightening any screws. Do not tighten the lock nuts down onto the washers until all screws have a locknut on them. Figure 19

29 Chapter 3: HexCrawler Assembly Page 23 CAUTION: Do not over tighten the (4) - #4 screws to the servo mount as it will bend the aluminum servo mount and the servo blank. Tighten the screws until the lock washer just starts to make contact with the nut and then turn the screw with a screwdriver ½ to ¾ of a complete turn! Figure 20: Top Servo Installation When completed, the leg assembly should like Figures 20 and 21.

30 Page 24 HexCrawler Kit Figure 21: Leg Assembly - Front View

31 Figure 22: Leg Assembly Rear View Chapter 3: HexCrawler Assembly Page 25

32 Page 26 HexCrawler Kit 13. Attach the rubber bumper to the bottom of the lower leg assembly with the ¼ #4 screw. The screw should be inserted into the rubber bumpers recess and then screwed into the lower leg assembly (Figure 22). Figure 23: Attaching the Rubber Bumper. The plastic hole is not threaded for the #4 screws but you may use a servo horn screw to self-tap the plastic threads. NOTE: The rubber feet may be too grippy on carpet surfaces, causing excessive torque and current drain on the horizontal servos. The result may be a jittery walk or incomplete movements. One solution is to use more slippery feet. U.S. customers can purchase Magic Sliders from Home Depot for $6.98. Magic Sliders are intended to be used on the bottom of furniture to easily slide pieces around the house. Magic Sliders seem to be perfect for the HexCrawler and provided dramatic walking improvements on carpet and cement on the Parallax HexCrawlers.

33 Chapter 3: HexCrawler Assembly Page 27 LEG PIVOT INSTALLATION Figure 24: Leg Pivot 14. Glue the black plastic leg pivot to the bottom of the lower servo with its long edge placed flush against the servo holder with the shorter edge of the plastic leg pivot even with the outer edge of the servo, oriented towards the leg joints as shown in Figure 25 and 26. CAUTION: The best type of adhesive for this operation is clear Liquid Nails for small projects. Do not use quick drying adhesives as they dry too fast and will not allow you to make any adjustments. Liquid nails dries hard and provides a strong bond but dries slow enough to allow you to shift the plastic pivot to make any final adjustments. Do not put glue near the hole or add excessive amounts of glue to the plastic leg pivot as it may seep into the hole during installation! Ensure the hole is clear of glue after installation. Wipe any excessive glue with a cloth.

34 Page 28 HexCrawler Kit Figure 25: Leg Pivot Orientation

35 Chapter 3: HexCrawler Assembly Page 29 Figure 26: Leg Pivot Orientation CAUTION: You must ensure that the leg pivot is positioned exactly as depicted in figure 26. Failure to do so will result in a leg(s) that will not be parallel with either the upper or lower deck of the HexCrawler after installation. 15. Set the leg aside to dry (the legs should dry for at least 4 hrs.) and repeat the build process for every leg in your HexCrawler.

36 Page 30 HexCrawler Kit PREPARING THE HEXCRAWLER S UPPER DECK The upper deck can be identified by the 3 holes at the ends of each of the leg decks (1 large hole and 2 smaller holes). Locate the upper deck and have it ready. 1. Drill out the round servo arm with a 7/64 drill bit in the second hole from the center hole of the 4 hole pattern on both sides of the servo arm (Figure 27). Figure 27

37 Chapter 3: HexCrawler Assembly Page Using (2) 3/8 #4 screws, washers and lock nuts, install the servo arm to the upper deck ensuring that the flat side is mounted to the upper deck as shown in Figure 28. Figure 28: Upper Deck Servo Arm Installation

38 Page 32 HexCrawler Kit 3. Repeat step #1 and #2 for all of the leg decks. When completed, the upper deck should look like Figure 29. Figure 29: Completed Upper Deck

39 Chapter 3: HexCrawler Assembly Page 33 INSTALLING THE SIDE SUPPORTS 4. Using a 3/8 #4 screw, install the side supports to the upper deck as shown in Figure 30. Figure 30 CAUTION: Ensure that the shape of the side support matches the shape in the upper deck when installing. 5. Repeat this process for every side support in your kit.

40 Page 34 HexCrawler Kit INSTALLING THE FRONT AND REAR SUPPORTS 6. Using (2) 3/8 #4 screws, install the front and rear support bracket as shown in Figure 31. Figure 31

41 Figure 31a Chapter 3: HexCrawler Assembly Page 35

42 Page 36 HexCrawler Kit INSTALLING THE LEG ASSEMBLIES TO THE UPPER DECK 1. To ensure that the servo wires do not get in the way of the following steps, secure the servo wires with the cable ties provided in your kit. CAUTION: Perform the following procedures one leg at a time.. 2. Place the assembled upper deck on a clean, flat surface with the round servo arms, front and side braces facing up as shown in Figure 32. Figure 32: Upper Deck Assembly

43 Chapter 3: HexCrawler Assembly Page Take a completed leg assembly and insert the legs upper round servo spindle into the upper decks round servo arm as shown in Figure 33. Figure 33: Installing a Completed Leg Assembly CAUTION: Remember to attach the correct leg to the correct side of the upper deck. The back face of the servos should always be facing towards the rear of the upper deck.

44 Page 38 HexCrawler Kit 4. Once inserted (do not secure it with the stock servo screw yet), gently swivel and adjust the leg (taking it out of the servo arm rotating the leg clockwise or counterclockwise and then reattaching it to the servo arm) so that it swings freely approximately 90 degrees towards the outside of the upper deck from approximately the 9 o clock position to the 3 o clock position as illustrated in Figure 34 and 35. Figure 34

45 Figure 35 Chapter 3: HexCrawler Assembly Page 39

46 Page 40 HexCrawler Kit 5. Once the leg is set correctly, secure the leg using the stock servo screw in Figure 36. Figure 36

47 Chapter 3: HexCrawler Assembly Page Repeat steps 3 through 5 for the remaining (5) legs in your kit. Once all of the legs have been installed, your HexCrawler should appear like Figure Put a small amount of white grease (or equivalent) into each of the plastic leg pivot holes. The grease will make attaching the upper deck to the lower deck easier. CAUTION: Do not attempt to attach the upper deck assembly to the lower deck assembly without the grease being applied or you may damage your HexCrawler! 8. After applying the grease, place the upper deck assembly in Figure 37 below to the side of your work area. Figure 37: Completed Upper Deck Assembly

48 Page 42 HexCrawler Kit PREPARING THE LOWER DECK 1. Install the (6) 2/56 threaded brass rods to the lower deck as shown in Figure 38 below. Repeat this step for all of the lower leg decks. Figure 38: Lower Deck Assembly

49 Chapter 3: HexCrawler Assembly Page When all (6) of the threaded brass rods have been installed, the HexCrawler s lower deck should look like Figure 39. Figure 39: Completed Lower Deck Assembly 3. Lightly grease the (6) 2/56 threaded brass rods.

50 Page 44 HexCrawler Kit ATTACHING THE UPPER DECK ASSEMBLY TO THE LOWER DECK ASSEMBLY ALTERNATIVE: Dead-bug assembly is also possible in this step. To do this you d use some white grease to hold the washers on the lower deck with white grease. Place the robot on it s back and then lower the bottom deck onto the bottom of the Crustcrawler. 1. In order to properly attach the upper deck assembly to the lower deck assembly, you will need to place the lower deck assembly onto an elevated platform. A pile of books that is slightly wider and longer than the lower deck assembly will work fine. The height of the books combined should be greater than 3.5 to 4.00 inches. This height will allow for clearance of the legs when attaching the upper and lower deck assemblies together. Figure 40

51 Chapter 3: HexCrawler Assembly Page Carefully take the upper deck assembly and lower it onto the lower deck assembly, ensuring that the holes of the 2/56 threaded brass rods align with the plastic leg pivot holes at the bottom of each the leg assemblies. CAUTION: Do not force the brass rods into the plastic pivot holes at this point! Doing so may damage the HexCrawler assembly! 3. Once the upper deck assembly is resting on the brass rods, carefully align each brass rod with each of the holes of the plastic leg pivot holes. 4. One leg at a time, gently swing the leg forward and backward horizontally until the brass rod just starts to go into the hole of the plastic leg pivot. Perform this step for each leg. CAUTION: At this stage, do not force the legs all of the way onto the brass rod as doing so may damage the leg assembly. 5. Once all of the legs are about 1/16 to 1/8 onto the brass rod, repeat this process until all of the legs have been seated completely onto the #4 washer of the brass rod. 6. Holding both decks together, carefully place your crawler onto its rear support bracket. This will make it easier for you to install the front, rear and side supports screws in the following steps. 7. Using a 3/8 #4 screw, secure the side supports to the lower deck assembly as shown in Figure 41.

52 Page 46 HexCrawler Kit Figure 41: Side Support Assembly 8. Using a 3/8 #4 screw, secure the front and rear support bracket assemblies as shown in Figures 41 and 42.

53 Figure 42: Front Support Assembly Chapter 3: HexCrawler Assembly Page 47

54 Page 48 HexCrawler Kit Figure 43: Rear Support Assembly 9. Carefully place the HexCrawler back onto the elevated platform.

55 Chapter 3: HexCrawler Assembly Page 49 INSTALLING THE DOGBONES AND SERVOS 1. With a 7/64 drill bit, drill out the second hole from the center hole of the servo arm as shown in Figure 44. It does not matter which of the (4) arms are drilled. Figure Attach the ball link with the #2 washer, lock washer and lock nut (Figure 45). The ball should be orientated towards the flat side of the servo arm. Cut off the servo arm to the left or 9 o'clock position from the servo arm that has the ball link installed. This servo arm's removal will ensure that the servo arm will not interfere with the operation of the leg assembly during its walking sequence. The remaining servo arms can also be removed as they do not serve any functional purpose.

56 Page 50 HexCrawler Kit Figure With the 2/56 threaded ball oriented upwards, install the servo arm to the servo spindle on the lower servo of the leg assembly and secure the assembly with the stock servo screw (see Figure 46 and 47).

57 Figure 46: Servo Arm Installation Left Leg Chapter 3: HexCrawler Assembly Page 51

58 Page 52 HexCrawler Kit Figure 47: Servo Arm Installation Right Leg Cut off the three remaining horns on the servo which are not being used after the ball is installed.

59 Chapter 3: HexCrawler Assembly Page 53 Figure This is one of the most important steps in this manual. Facing the front of the HexCrawler so the servo horns are showing, gently turn and re-install as necessary the servo control horn (keep the screw off for the moment) so that it swings from 11 to 7 o clock in the clockwise direction for the legs on the HexCrawler s right side and from 1 to 5 o clock in the counterclockwise direction for the legs on the left side of the HexCrawler (see close up above). 5. Repeat steps 1 5 for all of the legs on your HexCrawler.

60 Page 54 HexCrawler Kit 6. Join the 2 dog bones by threading the 2/56 threaded rod into each end of the dog-bones. Install the threaded rod completely into 1 dog-bone before threading the other (Figure 49). Repeat this step for all of the legs on your HexCrawler. This is often easiest done with a small vise. Don t grip the dog bones or the threaded rod too hard or you could damage the parts. Figure 49: Dog Bone Assembly Tip: Place the 2/56 threaded rod into a padded vise and use an adjustable wrench to turn the dog-bone onto the threaded rod. Figure 50: Completed Dog Bone Assembly CAUTION: If your dog bones do not thread together correctly, don t use glue to hold them in place. You have two choices for fixing this problem: Contact Parallax for replacement parts via info@parallax.com. Go to a local hobby shop and get Du-Bro #188 ball link sockets for replacement sockets and standard 2/56 threaded rod.

61 Chapter 3: HexCrawler Assembly Page Snap on the assembled dog-bone to the 2 ball joints on the leg assembly. Repeat steps 4 and 5 for each leg (see Figures 51 and 52). Warning: Ensure that you support the back of the main leg actuator when snapping on the dog-bone to the ball joint or the leg actuator may bend Figure 51

62 Page 56 HexCrawler Kit Figure 52

63 Chapter 3: HexCrawler Assembly Page 57 TUNING THE LEGS OF YOUR HEXCRAWLER 1. Using a 11/32 wrench or socket along with a Phillips screwdriver, tighten all of the lock nuts on the 1.25 #8 screws just tight enough so they can be turned by hand. (screws 1 4 only, see Figure 53) Figure Ensure the lower leg is as vertical as possible (for best accuracy, use a level) and then completely tighten the 1 #8 screw with the locknut (box 5 in Figure 53).

64 Page 58 HexCrawler Kit 3. Repeat the steps above for all of the legs on the HexCrawler. 4. After tightening each leg as per the steps outlined above, perform the following leg screw check: Tight Screws - Move the vertical lift servo so that the leg moves up and down and ensure that the leg moves freely and is not difficult to move or appears stiff. If the leg is difficult to move or appears stiff, one or more screws are too tight. Hand turn each screw until the tight screw(s) are found and loosen them just enough so that they can be turned by hand. Loose Screws - Move the vertical lift servo so that the leg moves up and down and ensure that the leg moves freely and that there is not too much horizontal play or rattle in the leg. If the leg appears loose, hand check each screw and tighten the screw just enough so that it can be turned by hand.

65 Chapter 4: Wiring and Tuning the HexCrawler Page 59 Chapter #4: Wiring and Tuning the HexCrawler This section describes how to build the circuit used in the HexCrawler example program. Build the circuit in small steps and verify that each section is working properly before proceeding to the next section. PARTS REQUIRED (1) BS2-IC Module and Board of Education (2) SSC2 - Serial Servo Controllers (12) Parallax Servos (already installed on the HexCrawler) (1) Seven-segment green LED (Fairchild MAN6480) (7) 1K Ω resistors (2) pushbuttons (2) 10K Ω resistors (2) 220 Ω resistors (1) 7.2 V battery (1) 9V transistor battery (if you intend on powering the BASIC Stamp separately) (misc) jumper wires HARDWARE MOUNTING Mount the two SSC2s and the Board of Education to the HexCrawler s top deck using the mounting kit which has the following parts: (12) #4-40 ½ screw (12) #4 ¼ nylon round spacer (12) #4-40 nut CONNECTING THE SSC2 TO THE LEG SERVOS Mount the two SSC2s to the HexCrawler s top deck. The HexCrawler requires two SSC2s to address its 12 leg servos. Each SSC2 can address up to 8 (0-7) servos. Connecting two SSC2s in series gives the HexCrawler access to 16 servos address. However we only need the first 12 addresses (0-11). Refer to the Scott Edwards Electronics SSC2 User Manual for detailed SSC2 descriptions and pin-outs ( CAUTION: check your connections carefully. The HexWalker program utilizes servo address and SSC2 settings that are described below. To connect two SSC2s in series simply attach the S and G pins, (S)erial In and (G)round respectively, of one SSC2 to the S and G pins of the other SSC2 (Figure 54). Next configure the jumpers as described below.

66 Page 60 HexCrawler Kit Jumper (R)ange on both SSC2s Jumper (B)aud on both SSC2s Jumper (I)dentification on one SSC2. Note: This SSC2 controls servo addresses 8-15 and will be referred to as SSC2 number two ) from this point forward. Range, Baud, and Identification are constants in the HexCrawler program. The HexCrawler program utilizes the SSC2 configured as described above. If the SSC2 configuration is changed the appropriate program constant will also need to be changed. For example: no Baud jumper will cause the SSC2 to receive data at 2400 baud. The program sends data at 9600 baud therefore the SSC2 will not understand the incoming data. Connecting the Leg Servos and SSC2s SSC2 two handles servo addresses 8 through 11 and SSC2 one addresses servos 0 through 7. Each leg contains two servos, one controls horizontal movement the other controls vertical movement. All horizontal leg servos have even addresses (0, 2, 4, 6, 8, & 10) while vertical leg servos have odd addresses (1, 3, 5, 7, 9, & 11). It is very important that the leg servos are connected to the correct SSC2 and SSC2 servo connector or the example programs will not function properly. The next 2 figures (Figures 54 and 55) show how to connect vertical and horizontal leg servos to an SSC2. F E SSC#1, servo 5 SSC#1, servo L K SSC#2, servo 3 SSC#2, servo 2 D C SSC#1, servo 3 SSC#1, servo J I SSC#2, servo 1 SSC#2, servo 0 B A SSC#1, servo 1 SSC#1, servo H G SSC#1, servo 7 SSC#1, servo 6 Servos moving legs vertically connect to odd numbered SSC2 ports. Servos moving legs horizontal connect to even numbered SSC2 ports. Figure 54: Servo and SSC Connections

67 Chapter 4: Wiring and Tuning the HexCrawler Page 61 Vin Vin P15 Mini SSC2 #1 Install Jumpers R, B Serial Ground Mini SSC2 #2 Install Jumpers R, I, B Vss Vss A C E G I K B D F H J L Figure 55: SSC2 Schematic Figure 55 displays another view of how the legs servos are connected to the matching SSC2 number (1 or 2) and SSC2 servo connectors (0-7). Leg 1 is connected to SSC2 one servo connector 0 & 1, Leg 2 is connected to SSC2 one servo connector 2, & 3, Leg 5 is connected to SSC2 two servo connector 0 & 1 etc. Take time to double check your connections at this point. It is much easier to make corrections at this point than at the programming stage. Figure 56 is yet another view so you can pick the schematic or pictorial you would like to use to make the necessary connections.

68 Page 62 HexCrawler Kit Figure 56: SSC2 Connectors to Leg Servos

69 Chapter 4: Wiring and Tuning the HexCrawler Page 63 Connecting the SSC2's Serial In to the BOE Connect pin 8 on the Board of Education (Figure 57) to (S)erial In on SSC2 one. This is the SSC2 without an (I)dentification jumper. If a pin other than 8 is used to connect the BOE to SSC2 one the appropriate HexWalker program constant will also need to be changed. Figure 57: Wiring the SSC2s to the Board of Education

70 X X Page 64 HexCrawler Kit ASSEMBLING THE SEVEN-SEGMENT LED CONTROL SYSTEM The HexCrawler s example program is run using a two-pushbutton, seven-segment LED display system feedback. One pushbutton starts/stops the gait and the other selects the gait to be used. Assemble the two pushbuttons and seven segment LED system on the remaining space on the Board of Education. Pay attention to wiring details as you will need to fit your fingers onto the board to press the buttons. Figures 58 and 59 show the LED and pushbutton circuits. P6 P5 P4 P3 P2 P1 GF nc A B P0 1 kω LED s G F A B C E F E A G D C B ED nc C Vss Vss Figure 58: Seven-segment display schematic Vdd Vdd P Ω P8 220 Ω 10 kω 10 kω Vss Vss Figure 59: Pushbutton control system schematic

71 Chapter 4: Wiring and Tuning the HexCrawler Page 65 Power Supply Connections This is the trickiest part of finishing the circuit. Connect the SSC2 s SVO connection directly to the 7.2V battery. You have the option of building a wiring harness or using a space on the BOE s breadboard for connecting this power supply to both SSC2 s SVO connection. Connect the Board of Education to the 9V battery. Connect the SSC2 s SSC power supply to Vin from the BOE, which will be a 9V input. Connect all Vss (grounds) together. The SSC2 SVO/SSC power grounds are connected together, so the 7.2V battery will be grounded to the BASIC Stamp and SSC2 power supply once it is connected. There are many ways to do the wiring, but it is important that the SSC2 s SVO connection be connected directly to the 7.2V battery, not the BOE s power supply. For a long-term solution, you may wish to use a toggle switch for the entire power supply and connect the 7.2V battery to the BOE and the SSC2 s SVO connection.

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73 Chapter 5: Program the HexCrawler Page 67 Chapter #5: Program the HexCrawler Prior to running the HexCrawler we will check the individual circuit systems (the pushbuttons, the LED) and then configure the servos for running. All of the programs used in this chapter are available for download from the Parallax web site. If you need help understanding how to setup the BASIC Stamp Windows editor and download programs see the What s a Microcontroller? Version 2.0 text. TESTING THE PUSHBUTTON CONTROLS Run the following code to check the pushbuttons: ' ========================================================================= ' ' File... HexCrawler_Pushbutton_Test.BS2 ' Purpose... Simple checkout of pushbutton circuits ' Author... Parallax ' ... support@parallax.com ' Started... ' Updated AUG 2003 ' ' {$STAMP BS2} ' {$PBASIC 2.5} ' ' ========================================================================= ' -----[ Program Description ] ' Uses editor DEBUG screen to check button inputs. ' -----[ Revision History ] ' -----[ I/O Definitions ] Button1 PIN 8 Button2 PIN 12 ' -----[ Constants ] ' -----[ Variables ] btnval VAR Bit ' state of a button ' -----[ EEPROM Data ] ' -----[ Initialization ]

74 Page 68 HexCrawler Kit Setup: DEBUG CLS, "Button Test" ' -----[ Program Code ] Main: DEBUG CRSRXY, 0, 2 btnval = Button1 ' get state of button 1 DEBUG "Button on P8... ", BIN1 btnval ' display it GOSUB Show_State btnval = Button2 ' get state of button 2 DEBUG "Button on P12... ", BIN1 btnval ' display it GOSUB Show_State GOTO Main ' do it again ' -----[ Subroutines ] Show_State: IF (btnval = 1) THEN DEBUG " (Pressed)", CLREOL, CR ELSE DEBUG " (Not Pressed)", CLREOL, CR ENDIF RETURN If the circuit is wired correctly you will be able to press either pushbutton and see a 1 appear in the DEBUG window as shown in Figure 60. If you receive no response from the pushbuttons carefully check the wiring to see that you are connected to the correct BASIC Stamp I/O pins. Once it is working properly proceed to the next section to test the seven-segment LED. Figure 60: DEBUG Output from Testing Pushbuttons

75 Chapter 5: Program the HexCrawler Page 69 TESTING THE SEVEN-SEGMENT LED Run the following code to check the seven-segment LED: ' ========================================================================= ' ' File... HexCrawler_Seven-Segment_Display_Test.BS2 ' Purpose... Simple checkout of seven-segment display connections ' Author... Parallax ' ... ' Started... ' Updated AUG 2003 ' ' {$STAMP BS2} ' {$PBASIC 2.5} ' ' ========================================================================= ' -----[ Program Description ] ' ' Displays digits 0 through 9 on seven-segment display to test connections. ' ' Segment map: ' ' (a) ' ' (f) (b) ' (g) ' ' (e) (c) ' ' ' (d) ' -----[ Revision History ] ' -----[ I/O Definitions ] Segments VAR OUTL ' output on pins 0-7 ' -----[ Constants ] '.edcbafg ' display segments Dig0 CON % ' segment data for digits Dig1 CON % Dig2 CON % Dig3 CON % Dig4 CON % Dig5 CON % Dig6 CON % Dig7 CON % Dig8 CON % Dig9 CON %

76 Page 70 HexCrawler Kit DigA CON % ' hex A - F (10-15) DigB CON % DigC CON % DigD CON % DigE CON % DigF CON % ' -----[ Variables ] idx VAR Nib ' digit index ' -----[ EEPROM Data ] ' -----[ Initialization ] Setup: DIRL = % ' P0 - P6 are outputs ' -----[ Program Code ] Main: DO FOR idx = $0 TO $F LOOKUP idx, [Dig0, Dig1, Dig2, Dig3, Dig4, Dig5, Dig6, Dig7, Dig8, Dig9, DigA, DigB, DigC, DigD, DigE, DigF], Segments PAUSE 500 NEXT LOOP ' display all digits ' loop forever ' -----[ Subroutines ] If the circuit is wired correctly the BASIC Stamp 2 will display digits 0 through 9 on the seven-segment LED.

77 Chapter 5: Program the HexCrawler Page 71 USER INTERFACE TEST Run the following code to check the seven-segment LED with the pushbuttons: ' ========================================================================= ' ' File... HexCrawler_Interface_Test.BS2 ' Purpose... Test HexCrawler buttons and 7-Segment display ' Author... Parallax ' ... ' Started... ' Updated AUG 2003 ' ' {$STAMP BS2} ' {$PBASIC 2.5} ' ' ========================================================================= ' -----[ Program Description ] ' ' Scan HexCrawler buttons and update 7-segment display. Button1 increments ' the display, Button2 decrements the display. This program introduces a ' subroutine to scanning and debouncing both buttons without the use of the ' PBASIC BUTTON command. ' -----[ Revision History ] ' -----[ I/O Definitions ] ModeBtn PIN 8 ' select robot mode StartBtn PIN 12 ' start/stop robot Segments VAR OUTL ' output on pins 0-7 ' -----[ Constants ] '.edcbafg ' display segments Dig0 CON % ' segment data for digits Dig1 CON % Dig2 CON % Dig3 CON % Dig4 CON % Dig5 CON % Dig6 CON % Dig7 CON % Dig8 CON % Dig9 CON % Pressed CON 1 ' button states NotPressed CON 0 ' -----[ Variables ]

78 Page 72 HexCrawler Kit btns VAR Nib ' button holder btn1 VAR btns.bit0 ' debounced button value btn2 VAR btns.bit1 ' deboucned button value idx VAR Nib ' digit index counter VAR Nib ' current digit to display ' -----[ EEPROM Data ] ' -----[ Initialization ] Setup: DIRL = % GOSUB Show_Digit ' P0 - P6 are outputs ' initialize display ' -----[ Program Code ] Main: DEBUG CLS, "Button & Display Test", CR, CR, "Mode (P8)... ", CR, "Start/Stop (P12)... " DO GOSUB Get_Buttons ' scan buttons GOSUB Show_Buttons ' show states IF (btns > %00) AND (btns < %11) THEN ' one or the other pressed? counter = counter + btn1 // 10 ' increment if Button1 = 1 counter = counter + (9 * btn2) // 10 ' decrement if Button2 = 1 GOSUB Show_Digit ' update display PAUSE 250 ' 1/4 sec between changes ENDIF LOOP ' do forever ' -----[ Subroutines ] ' Show digit in "counter" on 7-segment display Show_Digit: DEBUG CRSRXY, 0, 5, DEC?counter ' update DEBUG screen LOOKUP counter, [Dig0, Dig1, Dig2, Dig3, Dig4, Dig5, Dig6, Dig7, Dig8, Dig9], Segments RETURN ' Scan and debounce both buttons Get_Buttons: btns = %0011 FOR idx = 1 TO 5 btns.bit0 = btns.bit0 & ModeBtn btns.bit1 = btns.bit1 & StartBtn PAUSE 5 NEXT RETURN ' assume both pressed ' scan mode button ' scan start/stop button ' debounce delay

79 Chapter 5: Program the HexCrawler Page 73 ' Show current button states Show_Buttons: FOR idx = 0 TO 1 DEBUG CRSRXY, 20, 2 + idx IF (btns.lowbit(idx) = Pressed) THEN DEBUG "Pressed", CLREOL ELSE DEBUG "Not Pressed" ENDIF NEXT RETURN ' move cursor ' check and display status

80 Page 74 HexCrawler Kit TUNING THE HEXCRAWLER S LEGS The HexCrawler_Servo_Setup.bs2 program is a routine designed to assist in centering up the servos. Downloading and Running HexCrawler_Servo_Setup.BS2 CAUTION: Please ensure that your HexCrawler is mounted on top of a box or elevated platform with its legs clear of your working surface before you run this program. When the program executes the HexCrawler will be in it s standing position, with all legs centered. If all 12 servos and 6 legs fired in the correct order, horizontally then vertically from leg 1 through leg 6, it is time to adjust the legs. The DEBUG terminal will let you send individual legs to different positions so you can see the values it will take to control the HexCrawler. ' ========================================================================= ' ' File... HexCrawler_Servo_Setup.BS2 ' Purpose... Movement Demo and Alignment Tool for HexCrawler Servos ' Author... Parallax ' ... parallax@parallax.com ' Started... ' Updated AUG 2003 ' ' {$STAMP BS2} ' {$PBASIC 2.5} ' ' ========================================================================= ' -----[ Program Description ] ' ' This program is designed to assist in aligning idividual servos on the ' HexCrawler. Servo number are 0 to 11 and numbered as shown below. Leg ' numbers appear in parenthesis. ' ' ' _/ \_ ' Even numbers = horizontal movement ' Odd numbers = vertical movement ' \ / ' _/ \_ ' 8 2 ' 9 3 ' \ / ' _/ \_ ' 10 4 ' 11 5 ' -----[ Revision History ]

81 Chapter 5: Program the HexCrawler Page 75 ' -----[ I/O Definitions ] SSC PIN 15 ' SSC serial output Segments VAR OUTL ' 7-segment display ' -----[ Constants ] #SELECT $Stamp #CASE BS2 : Baud CON $4054 ' 9600-N-8-1 #CASE BS2E : Baud CON $4054 #CASE BS2SX : Baud CON $40F0 #CASE BS2P : Baud CON $40F0 #CASE BS2PE : Baud CON $4054 #ENDSELECT Sync CON 255 ' sync byte for SSC HCenter CON 125 ' horizontal center RVStart CON 50 ' right vertical start LVStart CON 200 ' left vertical start HRoM CON 110 ' hori range of motion VRoM CON 150 ' vert range of motion '.edcbafg ' display segments Dig0 CON % ' segment data for digits Dig1 CON % Dig2 CON % Dig3 CON % Dig4 CON % Dig5 CON % Dig6 CON % Dig7 CON % Dig8 CON % Dig9 CON % Blank CON % ' display off Waiting CON % ' three horizontal lines ' -----[ Variables ] servo VAR Byte ' servo number pos VAR Byte ' servo position leg VAR Nib ' leg number ' -----[ EEPROM Data ] ' -----[ Initialization ] Setup: Segments = Blank DIRL = % DEBUG CLS, "SERVO MOVER"

82 Page 76 HexCrawler Kit Demo_Legs: ' right side FOR servo = 1 TO 5 STEP 2 GOSUB Show_Leg ' lift SEROUT SSC, Baud, [Sync, servo, RVStart + VRoM] PAUSE 200 ' center SEROUT SSC, Baud, [Sync, servo - 1, HCenter] PAUSE 200 ' lower SEROUT SSC, Baud, [Sync, servo, RVStart] PAUSE 200 NEXT ' left side FOR servo = 7 TO 11 STEP 2 GOSUB Show_Leg ' lift SEROUT SSC, Baud, [Sync, servo, LVStart - VRoM] PAUSE 200 ' center SEROUT SSC, Baud, [Sync, servo - 1, HCenter] PAUSE 200 ' lower SEROUT SSC, Baud, [Sync, servo, LVStart] PAUSE 200 NEXT Segments = Waiting ' -----[ Program Code ] Main: ' UI DEBUG CRSRXY, 0, 2, "Enter Servo #, Position", CR, "(Servo 99, Pos 0 ==> All to Neutral)", CRSRXY, 0, 5, "Last --> ", CRSRXY, 0, 7, " ", CR, " _/ \_ ", CR, " 6 0 (H)", CR, " 7 1 (V)", CR, " \ / ", CR, " _/ \_ ", CR, " 8 2 (H)", CR, " 9 3 (V)", CR, " \ / ", CR, " _/ \_ ", CR, " 10 4 (H)", CR, " 11 5 (V)" DO DEBUGIN DEC servo, DEC pos ' get servo #, position

83 Chapter 5: Program the HexCrawler Page 77 DEBUG CRSRXY, 9, 5, "Moving...", CLREOL, CRSRXY, 9, 5 ' position cursor for msg SELECT servo CASE 0 TO 11 DEBUG DEC servo, ", DEC pos, CLREOL ' show entries SEROUT SSC, Baud, [Sync, servo, pos] ' move servo GOSUB Show_Leg CASE 99 GOSUB Legs_Neutral DEBUG "All Neutral", CLREOL CASE ELSE DEBUG "Invalid Servo #", CLREOL ENDSELECT Segments = Waiting LOOP ' loop forever END ' -----[ Subroutines ] ' Move all legs to neutral position Legs_Neutral: FOR servo = 0 TO 11 IF (servo.bit0 = 0) THEN SEROUT SSC, Baud, [Sync, servo, HCenter] ELSEIF (servo < 6) THEN SEROUT SSC, Baud, [Sync, servo, RVStart] ELSE SEROUT SSC, Baud, [Sync, servo, LVStart] ENDIF GOSUB Show_Leg PAUSE 200 NEXT RETURN ' horizontal servos ' right side ' left side ' delay between servos ' Display current leg # on 7-Segment display Show_Leg: leg = servo + 2 / 2 ' calculate leg # LOOKUP leg, [Dig0, Dig1, Dig2, Dig3, Dig4, Dig5, Dig6, Dig7, Dig8, Dig9], Segments PAUSE 200 RETURN

84 Page 78 HexCrawler Kit Adjusting the HexCrawler's Legs Not all servos are created equal. Therefore, you might have to fine-tune the legs. After the program executes, it leaves the robot in the home position: centered horizontally and standing. When looking down at the legs they should appear perpendicular to the body. Don't worry if you can't get all the legs perfectly perpendicular. Being off a degree or two will not adversely affect the robot's gait. Refer to the horizontal and vertical adjustment information on the next two pages to adjust the legs. Horizontal Servo Adjustment 1. Loosen (do not remove) the side support screws on the same side as the leg as well as the lower front and rear support screws. (see Figure 61) 2. Remove the top horizontal servo screw. 3. Gently lift the lip of the top half of the servo body to pop the servo spindle out of its holder and rotate it so that the leg is as close to straight out from the body as possible. 4. Re-install the top horizontal servo screw. 5. Perform steps 1 4 for each leg that is not centered. 6. Re-tighten the side, front and rear support screws.

85 Chapter 5: Program the HexCrawler Page 79 61: Horizontal Leg Adjustment Vertical Servo Adjustment 1. Loosen the servo screw on the servo control horn and remove the servo control horn. (Figure 62) 2. Turn the servo control horn until it is aligned as close to 90 degrees vertical as possible. 3. Re-install the servo screw 4. Repeat steps 1-3 for every leg that needs adjustment.

86 Page 80 HexCrawler Kit Figure 62 The next procedure will ensure that all of the legs are evenly sharing the weight of the HexCrawler Once all of the servo arms have been adjusted as vertical as possible, place your HexCrawler on a smooth surface in a standing position. One leg at a time swing the legs forward and backwards and note any differences in resistance between the leg and the floor. For legs that appear to be bearing more of the weight than the other legs on the HexCrawler - Remove the dog bones from the leg and twist the dog bones closer together. Re-install the dog bone and re-test. For leg that appear to be bearing less of the weight than the other leg of the HexCrawler - Remove the dog bones from the leg and twist the dog bones further apart - Re-install the dog bone and re-test. Once all of the legs have been adjusted with the HexCrawler_Servo_Setup.BS2 program, you are ready to load and run the walking program.