OpenROV Guide 3 - Electronics We will now move to the assembly of the electronics that will control the ROV. Written By: OpenROV 2017 openrov.dozuki.com Page 1 of 33
INTRODUCTION We will introduce soldering in this guide. TOOLS: Acrylic Cement (1) Applicator for Acrylic Cement (1) Disposable Rubber Glove (1) Small Screwdriver Set (1) Safety Glasses (1) Electrical Tape (1) Soldering Iron and Solder (1) Helping Hands (1) Needlenose Pliers (1) Scissors (1) Wire Strippers (1) Flush Cutter (1) Utility Knife (1) Heat Gun (1) 2017 openrov.dozuki.com Page 2 of 33
Step 1 Camera Mount Acrylic Structure We are now going to build the electronics chassis for the ROV. We will start by building the camera platform. You will need five parts for this step. Start by removing the paper backing from the pieces. Cement the outer camera hinge to the outside of the camera mount. Use care to get the hinge perfectly perpendicular to the mount, as it will need to move freely within the housing. When working with acrylic cement it is recommended that you wear gloves, safety glasses, and work in a ventilated area. 2017 openrov.dozuki.com Page 3 of 33
Step 2 Attach the smaller arm ( the servo arm holder) to the main arm and ensure it is flush with the camera platform (the largest piece). Do the same for the other side. Make sure they both end up on the same side of the camera mount. You have completed the acrylic structure for the camera to mount onto. 2017 openrov.dozuki.com Page 4 of 33
Step 3 We will now build the electronics chassis. Make sure you have all the parts and then peel the paper backing off from both sides. Place two of the nylon screws (from the hardware bag) in the piece as shown. This will help keep the next piece aligned. 2017 openrov.dozuki.com Page 5 of 33
Step 4 Double check that your orientation is correct. It is possible to build this part backwards. Thick acrylic piece on top of thin acrylic piece. Make sure your parts match the picture. Once the pieces are aligned, place 2 nylon screws on opposite corners, then cement the acrylic pieces together. DO NOT CEMENT THE SCREWS IN PLACE! They are only meant to help align the two pieces correctly. Once cemented slightly, you may remove the screws and cement the rest of the piece. Step 5 Next, we will mount the long acrylic piece. This is attached to the side of the two pieces that you just cemented together. 2017 openrov.dozuki.com Page 6 of 33
Step 6 Attach the semi-circular pieces to both sides of the structure in the alignment shown. Step 7 Cement the small acrylic piece onto the front of the chassis. This will hold the servo in place. 2017 openrov.dozuki.com Page 7 of 33
Step 8 Topside Tenda Adapter We are now going to build the topside electronics box. This box will be made from two assemblies. Start by laying out pieces as show in image 1. Take off the backing ONLY from the sides facing up. When put together, the inside faces should have the backing off while the outside faces have the backing on. Step 9 Acrylic cement the pieces together. 2017 openrov.dozuki.com Page 8 of 33
Step 10 We will now construct the other side of the box. Build the second half of the adapter box much like the first. Lay out the pieces as show in image 1. Take off the backing only on the sides facing up. Assemble as shown in image 3 and acrylic cement. Step 11 Peel off backing from outside faces. Leave these pieces separate. 2017 openrov.dozuki.com Page 9 of 33
Step 12 Remove the 2 Tenda Homeplug Adapters from their box. DO NOT toss the box or the 2 ethernet wires. They will be needed in future guides. Put aside for now. Using a flat-tip screw driver, gently twist the tip to crack open the plastic lid from the adapter. Use this as a hinge to open the plastic box, and remove the lid. Be careful so you do not stab yourself with the screwdriver. With care, remove the top circuit board (power supply) from the adapter housing. The small circuit board with the LAN input (the bottom one) is the one you want. It should be removed easily at this point. Do the same with the other tenda. When finished you should have two identical circuit boards. Hardware hacking! 2017 openrov.dozuki.com Page 10 of 33
Step 13 We will now mount one of the homeplug adapter boards to the the topside electronics board. Line up both headers. Press firmly into place. Step 14 Place the completed topside electronics into the acrylic topside box half. You may have to angle your board in order to have the LAN connection fit in correctly. Attach the second piece of the box to close it up. Once closed, use tape to keep the box held together. When taping the box closed make sure not to cover the LED indicator lights. The reason we are not cementing the box closed is so you can get to the electronics later if there is a problem. 2017 openrov.dozuki.com Page 11 of 33
Step 15 Soldering Tutorial Use caution when soldering electronic components. The temperatures are 500 degrees and higher. Eye protection is required. If you have a soldering iron with variable temperatures, it is a good idea to adjust the temperature for what is being soldered. Any soldering that is done in close proximity to solid state components should be done at a temperature below 600 degrees. Other wiring (motors, other hardware) can use a higher temperature. There are various thicknesses of solder that can be used for the appropriate solder joint. A thinner solder wire is used for soldering smaller components. Solder iron tips come in various sizes and texture. For the OpenROV a small tip with a straight edge at the end is recommended. This will allow you to solder smaller joints, while giving the tip some stability when heating the solder pads on the circuits. You should heat the solder joint with the iron for approximately 5-10 seconds before putting any solder on the joint. The solder should run freely between the iron, the wire, and the solder pad. Once the right amount of solder is applied you should be able to remove the iron and see a nice shiny connection between the wire, and the solder pad. If there are holes, major discoloration, or giant globs of solder everywhere, your connection between the wire and the solder pad may not take place and your electronics may not work properly. Video (How to Solder Electronics) How to Use a Soldering Iron: A Beginner s Guide by How to Geek. 2017 openrov.dozuki.com Page 12 of 33
Step 16 Soldering The Light Board The first thing you will solder are the leads from the light circuit board. Start by stripping one side of the two pieces of red wire length and two pieces of black wire length. Tin the wires with a soldering iron. Tinning is an important skill, if you are unsure or unpracticed at it, refer to this great Instructable. Insert the wires into the two holes labeled "LEDS." Power (red wire) and ground (black wire) is labeled on the back of the board. 2017 openrov.dozuki.com Page 13 of 33
Step 17 Use a soldering iron to heat the wire and apply solder. It is very important not to get solder between the two wires or between the two pads (silver areas where the wires enter the board). This may cause an electrical short. If available use a small soldering tip and very little solder. Also it can help to place the soldering iron on the outside of the wires rather than between the two. Here's an example of where not to put the soldering iron. 2017 openrov.dozuki.com Page 14 of 33
Step 18 This is an example of a good solder connection. This is an example of a bad solder connection. There is a bridge between the solder joints that will cause an electrical short. Step 19 Use flush cutters to remove the extra wire from the front. Repeat this with the other red and black wires into the two holes labeled "LASERS." 2017 openrov.dozuki.com Page 15 of 33
Step 20 Solder Lasers to the Light Board Next, take two laser diodes (the third one in your kit is a spare) and strip 1/4" (6 mm) from each lead. Attach lasers to the labeled solder pads "Laser Diode." The red wire is positive and the blue one is negative. Solder these onto the board from the front. Use minimal solder and minimal heat for these connections. Be very careful to not create a solder bridge between the two connections, as this will cause an electrical short. Use diagonal cutters to cut of extra wire and solder. 2017 openrov.dozuki.com Page 16 of 33
Step 21 Because it is easy to create a short at this step, it is important to check each soldered pair of wires with a digital multimeter. To do this set your multimeter to continuity. If this is your first time running a continuity test, refer to this amazing guide by ladyada.net. If you detect any shorts, try to fix them by brushing a hot soldering iron between the connectors. If this doesn't work, you can also try using a solder sucker or solder wick to remove the solder. Step 22 If all the connections are good, you should have a completed light board and are ready for the next steps. 2017 openrov.dozuki.com Page 17 of 33
Step 23 Camera Preparation We will now prepare the camera to be mounted. Take the camera out of its box. Detach the base from the camera by pulling it off (a hard tug will do the trick). Remove the bottom swivel from the camera with a phillips head screwdriver. Unscrew the pin and push the crew out (the hex wrench works well). 2017 openrov.dozuki.com Page 18 of 33
Step 24 Clean up the wires by cutting off the tag, and the velcro strap. Make sure not to cut the wire. Remove the silver ring around the camera lens by using a flat head screw driver. It should pop off easily. You will still be able to focus the camera later. Step 25 Camera Blinders Next, we will make the blinders that keep the light from overpowering the camera. Place a section of the 1/4" black sleeve against the light board and cut 1cm above the top of the light board. Do this twice so you have two pieces. Use the heat gun to melt the ends of the pieces to prevent fraying of the sleeve. 2017 openrov.dozuki.com Page 19 of 33
Step 26 Place the acrylic camera mount that you made earlier on the webcam. Make sure the acrylic and webcam are both oriented as shown. Confirm that the laser holes and camera bottom are on the same side. Place the light board on the front of the acrylic piece. Have the soldered wires be on the bottom of the acrylic piece. 2017 openrov.dozuki.com Page 20 of 33
Step 27 Grab two of the smaller zip ties and place the cut 1/4" black sleeve over them as shown. Step 28 Attaching the Camera Route the camera wire under one of the zip-ties. It does not matter which direction the wire goes. Grab the zip-ties with the sleeves and attach them with the sleeve on the front of the light board. The connection of the zip-tie should be at the top of the camera. Cut off the excess zip tie with a diagonal cutter. 2017 openrov.dozuki.com Page 21 of 33
Step 29 Attaching the Tenda Adapter to the Controller Board Next, we are going to work on the remaining electronics. Insert the RJ-45 ethernet (LAN) Jumper into the Tenda adapter board. Place the Tenda board onto the ROV controller board. There are two 6 pin connectors that were designed to accept the tenda. Push the board onto the pins and ensure it makes a straight connection. The other end of the ethernet jumper will be plugged into the Beagle Bone Black. Step 30 Remove BeagleBone Black from its box. Keep the USB wire it comes with as well as the desiccant. 2017 openrov.dozuki.com Page 22 of 33
Step 31 Attaching the Beagle Bone to Controller Board Place an 8mm nylon M3 screw through the hole on the electronics board. Thread the standoff onto the screw. Remove your BeagleBone Black (BBB) from the box and attach the other end of the Ethernet jumper to your BBB. Keep the USB wire that comes in the box. You will need this to operate the ROV. Press the BeagleBone Black onto the extended header set on the Controller Board as shown. Make sure the header pins on each board are aligned with each-other properly! Secure the BeagleBone Black to the nylon standoff using an additional nylon M3 screw. 2017 openrov.dozuki.com Page 23 of 33
Step 32 Attaching ESC's and Servos Tuck ESC wires under BeagleBone Black for wire management. You should now have a completed controller board! 2017 openrov.dozuki.com Page 24 of 33
Step 33 Assembling the E-Chassis Components We will now combine the front and rear electronics chassis. Have the camera mount be oriented with laser sockets as shown in image 1. Place onto rear chassis with the two square holes at the top. With your 8mm M3 nylon screw and nut, attach the camera mount onto the controller board acrylic. Make sure to screw on the nut snugly to allow the camera mount to rotate up and down without much resistance. Use pliers to hold the nut in place while using a flat head to screw in the nylon piece. There is a screw and nut on both sides. 2017 openrov.dozuki.com Page 25 of 33
Step 34 We will now modify the servo horn. Start by using a screw driver to remove the round white servo horn on the servo. Take the two-arm servo control horn (in the same box as the HS-81 servo) and cut off one of its arms using a diagonal cutter. Also use the diagonal cutter to remove the corners from the cut-off portion of the horn. This will allow the arm to fit inside the hole cut out in the Camera Mount arm. Wear eye protection when cutting the servo horn. Install the modified arm on the servo. 2017 openrov.dozuki.com Page 26 of 33
Step 35 Before mounting the servo to the E- Chassis, make sure the horn (white plastic part) is centered. To do this gently rotate it back and forth to its extreme left and extreme right. You can remove the horn and then adjust how the horn is placed on the servo so that it centered between the extremes. (see diagram). Step 36 Attaching Servo Place servo into the board on opposite side of the camera mount. Make sure you have the servo arm slide into the camera mount arm. Use electrical tape to keep the servo in place. 2017 openrov.dozuki.com Page 27 of 33
Step 37 Light Board and Camera Wires Thread the light board wires (4 in total) and USB cable through the center hole. Do not pull the camera USB cable all the way through. Step 38 Plug in the USB cable to the BeagleBone Black. 2017 openrov.dozuki.com Page 28 of 33
Step 39 Attaching the Controller Board to the Acrylic Chassis Bundle the wires that are threaded through the center and the servo wires towards the area where there is a gap in the acrylic as indicated in image 1. Once the wires are pushed there, place the controller board on top. Pull the USB cable on the other end to provide minimal wire slack. For wire management purposes, have the USB wire wrap around the DB-25 plug. 2017 openrov.dozuki.com Page 29 of 33
Step 40 Attaching the Controller Board to the Acrylic Chassis With the 16mm M3 nylon screws and nuts, begin securing the board onto the acrylic. Attach to 4 designated corners. Don't over-tighten the screws. The controller board should be flat (top of image 3). Over-tightening the screws can cause the controller board to bend, which may cause solder joints to break (bottom of image 3). Step 41 Getting Voltage to the Light Board See which ground and power wires go to which side of the controller board. Port side is Lasers and Starboard side is LEDs Plug in LED and laser wires to their designated pins. LEDs go to P1 on the and lasers go to P2. 2017 openrov.dozuki.com Page 30 of 33
Step 42 Attach servo wires to designated pins on the other side of the board D11. Make sure black wire is oriented to the outside. Step 43 Using clear acrylic for visual clarity for this step. With the excess webcam wire, you will begin tucking it inside the E-Chassis. Push the wire inside the hole till it pushes against the outer edges. You want to make sure you push as far out as possible to have as much room to fit the entire wire length inside. Using the hex wrench helps a lot to push the wires farther out. 2017 openrov.dozuki.com Page 31 of 33
Step 44 Once tucked in, test your camera mount moving back and forth. Preferably there should be no force pulling the camera when at its extremes Step 45 You Are Now a Robot Technician! Congratulations! You have completed the construction of the E-Chassis! 2017 openrov.dozuki.com Page 32 of 33
Step 46 Continue your build by progressing to Guide 4. This document was last generated on 2017-06-20 01:23:16 AM. 2017 openrov.dozuki.com Page 33 of 33