An Adventure in Engineering Design, Programming, and Pursuit of Robotic Projects: Updated 09/07/2009 |
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An Adventure in Engineering Design, Programming, and Pursuit of Robotic Projects: Updated 09/07/2009 |
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Project log for Inky STATUS - IN PROGRESS
Inky, Blinky, & Clyde? by Justin S. McFarland (June 15, 2009 - Updated September 7, 2009) As really a re-introduction to square one - Inky was chosen for three reasons - it's simple < 2 weeks to build, I had most of the parts or the parts were cheap, and it accomplished a number of the Squidlian's primary requirements. I learned of this design through an outreach project that I volunteered for April 2nd, 2009. I came to realize that the SeaPerch design for which the Prince William School District was having its underwater ROV project centered around was based on West Coast World's Build Your Own Underwater Robot. When I learned this - I was really hooked. I saw the 9th grader's creations and judged their journals, but I figured wow this is a nice platform for experiments. So I bought the book and gathered ideas while I was waiting to finish grad school. Rapidly I had parts cut for not only the SeaPerch concept but two SeaPerch craft and a SeaFox class. Three vehicles! Clearly as they were all related in some form they needed common names: Inky, Blinky, and Clyde seemed pretty appropriate. Requirements: Construct a simple remotely operated vehicle:
Documentation: 1. Commented source code (e.g. set of BS2 files), microcontroller(s) (e.g. 1- BASIC STAMP 2), compile method/compiler (Parallax Basic Stamp Editor v2.3), and platform (Windows XP). Source code comments must declare all variables used & intrinsic function calls (e.g. FREQOUT). 2. CAD files, design drawings, and/or images taken during assembly with dimensions 3. Bill of Materials / Parts List; costs; vendor(s) 4. Electronics schematics & circuit verbal description using IEEE symbology as much as possible 5. Discussion about tips on building the ROV, mistakes to avoid, or possible additions that could/should be added to make it better. 6. Video (if possible) of the robot in action to show what it can do and why anyone in their right mind should try to repeat the construction process
Updates September 7, 2009 Inky 2.6 - Night Testing and Refurb Weekend tests went a bit south when the primary power line that I soldered on the 4th came off the switch. This occured when the box lid and the box itself were jerked apart and the cable not being of significant length was strained and pulled off the weak bond. The 10 A fuse was also blown during this adventure (outside at 1230 am).
Field Test objectives of V2.5 and Blinky V1.1 (results):
Image of the 12.5" x 12.5" gate from Blinky on 6 September 2009
Dad assisted in soldering the power cable switch back on and corrected soldering with the Green LED panel to the 9V battery connector for the 3pm test. The test was concluded when Daisy (the pup) being excited knocked over the control box and some cables were pulled ending the daytime test on September 6th.
Refurbishments for V2.6:
Testing objectives for V2.6 and Blinky V1.2: Scheduled Evening of 11 September 2009
September 4, 2009 Inky 2.5 - Powered Up Inky 2.5 was powered up tonight and finished up with the LED array control mounted to the power control box. This is a simple SPST switch to turn it off and on. I may move it to a relay powered circuit using the PS2 controller to toggle it on/off. However given the time amount to field it this weekend, the switch was simplest. I also moved the power switch to a LED SPST switch the same as the DPDT switch box. This made it easier to remember when power was left on at the end of a run.
V2.5 Summary
August 27, 2009 Inky 2.5 Inky's hull is modified to move vertical thruster to the center of mass, move the tether to the rear section by adding another copper loop to the back strut, and add an LED array for the 4th control line previously unused. To accomplish this I had to
Wiring documentation:
August 26, 2009 Blinky Prototype & The Detachment of Data! Trials for the Camera 1 integration into the Blinky structure began. A new project log is being setup to follow the progress and the continued camera platform development and testing; target testing; and LED waterproofing to be used for tracking or lighting. - August 25, 2009 Camera Test! After some more trials with the epoxying this weekend, I used Marine Silicone on strategic sections of the adapter for pre-epoxying and let sit for 24 hrs. I then epoxied and let sit for 24 hours. Then threw the camera while attached to the Ethernet adapter into the tub. For a year of waiting... the time has come... soon... we will have video of Blue Boat!
August 22, 2009 More details on my favorite Goop, Infusions of Cash Ordered McMaster Goo, details on gooing, and camera test status.
McMaster Order x 2 for the Epoxy 3M Scotch-Weld Electrical Insulating Adhesive for Encasing (Potting) 3M Adhesive Duo-Pak Cartridge DP-270, 6.7 Ounce (200 Milliliter), Clear (7467A123) Ideal
for bonding electrical components, this two-part adhesive is also thick
for encasing items in adhesive (potting). Resists heat and retains
insulation properties under high humidity. Bonds aluminum, brass,
copper, stainless steel, steel, ABS, acrylic, polycarbonate, ceramic,
fiberglass (FRP), glass, and rubber. Begins to harden in 60-70 minutes;
reaches full strength in 48 hours. Mix ratio is 1:1. Dielectric strength
(the ability to withstand electrical voltage without rupture) is 850
volts/mil. Meets UL 94HB. This product is VOC compliant in all 50 states
as of October 1, 2008.
Update Video Camera Ongoing testing with the video camera this week. I spliced apart the USB wire to try to extend the cable 25'. As noted on August 19th this didn't work. So I got out the two Ethernet adapter kits for extending USB over Ethernet and experimented with their use - still work! I tried out epoxy on one pair but no joy (details below). Bob dug up the two Ethernet cables from last year's Squidlian project and we'll use one set with Blinky.
Camera notes:
Camera 2 (control - no epoxy)
Camera 1 (after epoxy in the lens cavity)
Update Epoxy Status On Thursday (20th) Bob came over to help out survey the epoxy situation. He assisted in teaching a bit about the skill and art of epoxying and we mixed up a batch to try out on the Ethernet adapter & the LED flasher. On Friday (21st) I mixed up a batch myself for the other end of the adapter and put the rest into the camera to eliminate its tackiness. All of that worked; however I discovered after trying to test the adapters that the Ethernet plugs no longer fit inside... Some epoxy leaked through and solidified inside where there are grates of plastic guarding copper connections where the RJ45 plugs in. s
August 19, 2009 - Gaa Gaa for Goop Goop Two objectives for this evening were: 1.) to test the camera wire spliced into a 25' Ethernet cable and 2.) assure that the camera can last for 30 minutes of solid on time in the epoxy and survive. The first test failed. When plugging into the USB spliced end, Windows detected a USB hardware device but it was considered malfunctioning. To resolve this issue I unsoldered the connections and bread boarded the two separated parts of USB cable into a set of 2 x 2 terminal blocks on a breadboard. The camera was then tested for the 30 minute duration event and all went well. The next step is to just patch in to the breadboard, the 25' of Ethernet cable to verify soldering wasn't at fault for the bad connection. If it was that the fix will be much easier. If it is not and the cable length is the problem for the signal strength to be high enough... well let's just hope its not that (although I do have the components to deal with that already).
Update - Signal Strength Test with the 25' Ethernet cable in the breadboard setup failed. Although I'm measuring only 1 Ohm (actually 0.7-0.8 Ohms) of loss per stranded wire. At the moment I don't really have a solution to this other than use the off-the-shelf USB to Ethernet cable converter. My guess is that that converter has a signal booster in it. So I'll need to ask around and see what I can find out about trying to boost the signal along the line to get it to connect in Windows. Else this is going to be a very short camera excursion.
August 18, 2009 - Power Outage... Well my unsaved... log entries from the 13th through today apparently have been lost in the world of software. An unexpected morning power outage reset my computer. Arrgh! So I'll try and summarize the past week's activities with the potting and epoxying (unfortunately there were a number of lessons learned on that list too...) But fortunately I still have my hand scrawled notes here and there.
LED Flasher Potting & Flasher Docs Components:
General circuit diagram
6 LEDs were placed in a matrix configuration. The circuit was tested prior to potting and the flashing failure had gone away upon the correction of some late night soldering mistakes that resulted in not following the circuit diagram. Fun with epoxy. This was the first test with the epoxy and to prepare I used some of the ABS plastic sheet from McMaster to cut out a pattern for folding up a rectangular prism with 5 sides and the top open to hold the protoboard & components. The objective for this design was to simplify things and fold up the edges into place... but that didn't work out very well.
The 4 open edges were (and still are) a pain. Hot glue was not sufficient to hold the sides together (springing outward). Rubber bands though amusing didn't really help. And I did clamp the sides in place to try and have some epoxy dry them together and while this worked to a point, it in combination with the hot glue (hot glue came last) resulted in a big gooey mess. Unfortunately this was just the start of gooey messes. I having thinking I had good seals on the corners, tried out the 3M Epoxy compound per the directions which says to apply the epoxy directly to the dry surface. Ok, fair enough. I guess I don't really need to mix this stuff (WRONG!).
Regardless there is still (after 5 days) some of the compound that has not reacted with the hardener and leaks out of the sides of the box and onto the paper surface forming a lovely pile of stickiness in its place. Fortunately the stuff works well enough to declare a minor victory. The circuit is waterproof... and the lights still flash underwater. Meanwhile, I have to just deal with the tacky surfaces and try and clean them up every time I handle it.
Lessons learned:
Webcam Potting I started the webcam potting project shortly after potting the flasher circuit, mostly out of impatience. I cut a box out of ABS again, but this time just did the parameter for folding having just one side to mend of the folding sides. Then I added one of the clear card deck shells to the mix by 30 min epoxying / hot glue tacking to the ABS plastic shell. Ok, that worked well enough. But the next time, I want to use the four sides after I get the camera mounted to the plastic with silicon before integrating the 4 sides with the front clear face. The primary issue with the camera is that the wire has a lot of evil in its blood and it won't stop trying to rotate or tip or whathaveyou. So when trying to silicon the camera to the clear side, the camera moves all around inside smearing up the surface and you have to start over again. After the 2nd or 3rd time at this, I didn't reapply more silicon and went in as is with a sparse amount. This was my undoing. The silicon did not seal the surface of the camera to the surface of the shell well enough to prevent seepage of epoxy to run through... thus filling up the cavity around the lens and adding significant image distortion (tested camera Monday evening).
Early shot from Camera 1 indicating poor performance
An O-ring and apply pressure to seal the camera to the clear surface first prior to integration with the box might have avoided this.
The epoxy was mixed a bit more this time, but not well enough initially to avoid the tacky goo pile yet again. The denser solid substance sank to the bottom (good) but left unhardened goo at the top (bad). I tried to mix additional epoxy into the compound and this did help, but a layer of goo still remained.
Lessons learned
August 13, 2009 - Flashing Failure! Well, somewhere along the line one of my resistors isn't connected to the capacitor & timing circuit correctly because it just has a delay to start then fires on. So the resistors don't seem to be draining the capacitor. Fix tomorrow I hope? Also, need to cut out a box for the flasher panel to be potted inside. Should be interesting.
August 12, 2009 - Washington DC Metropolitan Robotics & Automation Group Presented Inky at the monthly club meeting. General curiosities abound, I talked about the background of the project and where I was going next (i.e. the camera). I started protoboarding the LED flasher for 12VDC with 6 red LEDs. This will be potted in epoxy and tested before the camera.
I received my parts from both Parallax & McMaster-Carr on Monday and have been slowly getting around to using them.
August 9, 2009 So what next for Inky? The general principals have been completed for Inky. Those requirements have been exceeded with the addition of the microcontroller derived control mechanism. So onward to Inky 3.0 - outfitted with some LED and camera action.
August 8, 2009 - What's the Equivalent Marine Term for Pre-flight? Did some video taping early afternoon / late morning with Mr. Bill. Modified the hook per recommendation earlier by drilling a 7/64" hole into the hook and through the PVC arm and screwed in a sheet metal screw. This halted its rotation. The next pre-mission checklist event was to get some rings prepared. I had to do so quickly so I got two of the larger PVC rings I made up earlier, filled them with water, and put some buoyant material on and electrical taped them to the frame.
Objectives for today:
Record: I retrieved a couple rings from the bottom of the 8' pool. Things started out odd since the rings were floating. They got away initially as I was pushing them and strayed out of range. So I had to shimmy my equipment down the edge of the pool. After that I brought them back to the side and stripped off the buoyant material until they sank. From there I went on a few diving missions.
The tether itself was being a bastard again lifting the rear end of the vehicle up (pitch down) and rolling it to the left (port). This was because many of the tether floats have come loose since the initial gluing. Also I did not yet move the tether connection to the center of the vehicle. The rings themselves were pretty easy to get up. And Bill recorded two retrievals. I did about 5 or so retrievals in 20 minutes we were at the pool. There were a few problems notably the hook arm was loose and due to the tilting effect at the greater depth (this didn't really happen in the shallower pool at my parents) it smacked off the cement floor bending the arm (not the hook) upward about its pivot axis. After this occurred I aborted and went to the surface to tighten (at Bill's suggestion) the arm with the Phillips head screwdriver. I retrieved a ring and then upon diving the wiring got wrapped about the port engine and it stopped turning. I surfaced immediately and Bill pulled in the tether so we could free it (Bill did a lot of work and got wet and was cranky, but we accomplished the mission!). So went down again and we got this video.
Notes on control in the 8' vs. 4' as well as general observations:
Future design options
August 6, 2009 Potting... epoxy and more Purchased some potting epoxy (from McMaster) to start work on the waterproofing of the webcam and the LED array. Will charge the depleted batteries tomorrow. Purchased a number of 3-wire extension cables for the H-bridge controller.
August 4, 2009 Inky 2.0 Full up testing of the Inky 2.0 system with 'production' PS2 control in the operational environment. The design experienced some initial setbacks with the blowing of a 2.0 Amp fuse in the control box, low battery charges, and mis-wiring of the propellers but all was overcome. Inky 2.0 successfully lifted pool rings from the 4' depth of the McFarland pool as well as rings floating on the surface (albeit submerged). Both rings were valuable at understanding the pursuit and control capabilities of the Inky 2.0. Its superior handling was a marked difference over the original DPDT switch arrangement. Rings were easily grasped when within 10 ft line of sight to the controller. An interesting problem came up though when outside that range, the vehicle was hard to see with the surface ripples at the slanted angle and in addition to the extended nature of the tether difficult to navigate precisely.
Battery Monitoring The analog voltmeter light array needs to be added to the control box of Inky 2.0 to understand the battery state high or low for both charging and discharging purposes. An electronic voltmeter would be nice, but doesn't fit will into this architecture unless the LCD screen was used to also display this data at the request of a PS2 button push (cool?)
LCD Screen Not mounted in the control box due to the lack of time to cut out a hole, etc. Also needed the control line for the H-bridges. Verified to work breadboard testing here
PS2 Control & Motor Control General instructions from Nuts and Volts Article 101: Playstation Control Redux and the Parallax forum. Design notes are here
Parts:
3 - Flex Bridge Design Based on the Power MOSFET H-Bridge design in Intermediate Robot Building by David Cook, Driving Mister Motor, this design is meant to be variable between two interface drivers to eliminate shoot through and add complete motor control or remain in the half-bridge configuration (standard). The shoot through occurrence is something to be mitigated per Cook's discussion on pp. 187-188 for PWM or rapid reversing situations (possible for autonomous control). This design is rated for 16V and I still have to determine the amperage...
Parts:
H-bridge notes - CLOSE THE GATE!!! Testing that occurred on 30-31 July noted that the amperage was rising on the power supply although no new outputs were being used. This was due to the open gate situation on the other H-bridges (each was tested individually but did not have control lines on all of them). This was noted in the book Intermediate Robot Building, but now I know exactly what the author was taking about.
LED Array The LED array was tested in the afternoon of the 1st of August to must satisfaction, no water was detected inside and the array was fine. However at night when air was much cooler another test was taken and the light flickered. Quickly it was ascertained that there was moisture inside the case due to condensation! So this concept has failed and epoxy potting is going to be required.
Parts:
Probe The metal hook device (steel 1-1/2" pipe clamp) on Inky 2.0 is loose and requires a 2nd screw hole (#6 x 1/2" pan head sheet metal) to secure its orientation. Also when loaded with the ring, the vehicle is definitely bow heavy and a design for Clyde should include a second vertical thruster to handle the mass imbalance or do a better job to have the ring secured in the center of mass/buoyancy
New Control Box The new control box replaced the earlier simple version with the LED lighted switch and 3 DPDT switches. This box just has the power switch externally but houses all the electronics for the PS2 interface and the motor controller. The PS2 box has some additional room inside for stacked boards as well. A great attribute is that the PS2 controller cord is of sufficient length to be able to stand while the box itself can be on the ground thus reducing the weight in the user's hands to just the controller.
Parts :
Camera on a Stick Camera on a stick saw a prototype this weekend by combining the waterproof Olympus Stylus Tough camera with some electrical tape and the pool skimmer. This was used to do some quick video taping of the Inky 2.0 unit.
July 16, 2009 Inky & the PS2 Controller I tested out the PS2 controller with Inky in the water today. The test setup included separating the original control box from Inky and re-wiring the tether to the H-bridges. The motors themselves were reinstalled on Inky. The brown wires were setup with the vertical thruster, green with the port, and blue with the starboard as before.The objective of the test was to check out the loading of the motors under water and determine whether or not that would smoke the circuits. Each motor under load was generally in the 0.5-0.6 amps category. The motor that vibrated a lot however was sucking as much as 3.7 amps (especially when scraping on the side of the tub I was using to test it in). It also was the highest thrust motor.
The tub (i.e. the storage container) from earlier tests was revamped and filled 2/3 full. It was then brought into the test area and the sub lowered inside. The test setup was fairly typical as per the PS2 controller tests. The power supply was set to 12VDC. The wiring was reviewed to see if the H-bridges were missing any wires from the breadboard. The BS2 BoE was turned on to Level 2. The controller toggled to analog mode. Then tests began on the vertical thruster with the L1 and L2 controls - checked out fine without issues. Then the starboard thruster was tried. The amps jumped up significantly as mentioned. The motor also tends to jerk a bit taking more power and less power fairly erratically. I'm not entirely sure what to do about that motor whether it's a power supply problem with that motor or not. It behaved similarly in forward and reverse. Taken out of the water it reduced the load to 0.6-1.2 amps with the jerking still persisting. Still that didn't have too much an effect although it did concern me since the motor driver is rated only to 3 amps (the point of the test was to see about this constraint). Ironically it was the port motor however that smoked (though there was no blue smoke or pops there was the aroma of dead electronics). This was done while the motor was being toggled a bit perhaps too much back and forth? I'll need to verify that the driver died. It may have been the shoot through short circuit problem, maybe not.
So results? I'm concerned that two of my motors acted weakly and the other so strongly. I need to also investigate about running the drivers in parallel to see if I can have more current flow through them with my spares, if so, I'll definitely double up and then double the capacitors equally. I might also look to a current pump chip that Jim Bober was talking about at work earlier in the week. Other options include going to the full H-bridge instead of the half bridge configuration using two driver chips for the bridge with 4 control lines instead of two per motor. I'm definately not sure about that route due to the lack of pins. But I have 6 pins available (some of which might have been smoked due to the PS2 controller incident) so its possible to use some. I wanted to reserve two for serial communications however which would constrain all the remaining pins (assuming they work) for motor duty on two motors leaving the other motor a half bridge.
Control Box / Voltmeter Other thoughts - the control board will need a case. I also desire to know the voltage remaining in the batteries and may hook up the analog LED set from Squidlian in the case somehow. The control board also should be something not as expensive as the BoE and probably one of the carrier boards that is something that can be programmed still but I can solder with. The idea I had about this carrier board would be to solder some rows of female header pins on it and combine that with a modular protoboard setup that sandwiches with that setup.
LED Array & Camera The outstanding issue at hand is still the camera and LED array. I still want to use the 12VDC array but it needs to be waterproofed. The camera on a stick project still needs a camera! And I have two webcams. So I want to sacrifice one to the modular good of waterproofing and see what happens.
June 22, 2009 Visiting PA Inky visited the great state of Pennsylvania to run around in a new venue. A few things came to light on the journey: that the starboard thruster noted to be lagging actually locked up, was removed for further testing, and subsequently came back to life again (in its original hobbled state). A few modifications to the buoyant structure were made on the trip including the adding of several new smaller lengths along the forward and amidships vertical members and the addition of some bolts through the amidships t-sections to help with the CG offset in an experiment. The tether again was noted as being problematic especially for maneuvers and that it would be better served to be in the middle of the rear of the vehicle for control authority.
Purchases: Additionally on the trip several new wire nuts for #22 wire were purchased at Lowes ~$5 for packs of 2 packs of 25. This was to improve the wiring of the vehicle instead of being ad hoc with some sections with wire nuts and others braided together as I ran out of wire nut stores.
June 18, 2009 Calculations and Such Inky has gone into the world of CAD modeling. The base structural frame is shown here with each part a unique color. The foam and thruster assemblies haven't been added to the design just yet nor has the candidate armiture. The intension of this was to obtain the CG location of the base hull and perhaps get some moment of inertia estimates as well (why not?).
Lowes Gray Wirenuts 25 bag (53213)
June 16, 2009 Survived the Potomac! Inky got into the water beside Blue Boat tonight! In a fantastic achievement, I maneuvered quickly around Blue Boat's slip after tonight's sailboat race, proudly showing it off to Bob & Johanna. Bob was happy! Lots of questions about a video camera and so forth. We'll have to get that camera on a stick thing working or build a secure platform for the Olympus to try out with some lighting options on a control panel. It was indeed bow heavy with the arm and the foam piece came off. Fortunately the vertical thruster again saved the day. I'll do some engineering tomorrow to actually get the balance right (or closer) and also try out some additional foam material. I also have to work on the rings ballasting anyway. Have to get it done before Thursday night in order to have it working for my trip to PA this weekend and demo to the family on father day!
June 14, 2009 Armature and Math... *gasp* No pictures today but I did go to HD again and picked up 10 more 90 deg elbow pieces to help make some rings for Inky to play with. The new arm also was tried out today by drilling a hole through a left over section of PVC 1/2". Two rings were made out of 8 sections of 2-1/2" length 1/2" ID PVC. Another set of two rings was from the leftover spacer material 1-1/2" long. When water is inside the rings, they sink. When sealed they float. So of course some math needs to be done to fix that issue. Additional math needs to be done on the Inky unit to both try and move the center of mass / center of buoyancy line to the vertical thruster so it no longer has a bow down condition. At any rate I put on a arm made out of larger pipe clamp some screws and the PVC pipe. I put on a light piece of foam but haven't tested it or balanced it yet. This of course will make the front... even heavier!
June 12, 2009 Back to the Pool Following the trial on the 11th, I used 30 min epoxy from Tower Hobbies to secure the port and starboard props in place. I let it sit for about 10 minutes and then put on the first nut on each shaft to tighten against the prop. I let it sit for over 12 hours before putting the 2nd nut on again. I was careful not to over-torque to possibly break the epoxy. But nothing came of that. The epoxy was mixed in a Styrofoam cup with a thick tooth pick and spread around inside the prop and along the shaft. I dabbed the shaft with a Kleenex to mop up extra goop to try and ensure a more symmetrical mass distribution.
In addition to the epoxy I did some hot glue repairs to the net on the base. Some of the glue areas came undone and needed repaired, this was easily taken care of with reheating the effected area and adding some additional glue not that big of a deal. The last major change of note was the addition of the foam material to the tether. A larger float was measured out at around 8 feet. This worked well to keep the weight of the tether off the vehicle for the most part. The vehicle however still is bow heavy and negatively buoyant. It is however very nimble and the vertical thruster performs well to keep it mostly stable. The problem is when going full speed ahead the bow goes down the vehicle experiences negative lift of some type and wants to go down. The vertical thruster then acts like a small helicopter blade and the vehicle skims along the bottom lifting off the ground a bit... an interesting behavior. I had thought to put Cap'n Duck'ems up front and strapped in via a zip-tie, but opted with the attempt at adding a temporary concept of a arm.
Some videos!
June 11, 2009 Back from Alaska... now where's my sub? Returned from Alaska around midnight on the 10th (morning side). Went into work for a short while then started looking around at the parts that were awaiting me at Mr. Bill's. On the 11th, I finished construction of the port and starboard thrusters. I mounted them to the side bow vertical frame pieces. The one side is mounted in the standard frame holes, while the other side forced me to drill another hole for mounting. I verified the alignment with a level prior to drilling that side and the result seems pretty good. I also mounted a new bow piece of foam material to compensate for the additional thruster weight. I zip-tied it to the bow pipe and through the green fence material. These ties were left over from a previous project (not sure what I needed them for on Squidlian... I know I used some on the Arduino Bot). Anyway they came in handy and were used on both the wire tether and the floats. Upon mounting of the thrusters they were attached the sub to the red tether via wire nuts or electrical tape preferring wire nuts but I ran out. I tested the engines and control box outside the tub and then in the tub. In the tub, I found that the port and starboard props are much much looser than the vertical thruster and that consequence. For some reason these versions of the same size prop aren't threaded at 1/8" as the vertical guy was. So I went with the double #40-40 nut combination again on these thrusters and tested that out. Unfortunately that didn't work, so I tried thick CA to glue them in place. That worked in the tub, so I took the sub down to the pool in the container it fit perfectly in. I also put the batteries in their own separate container for transport and keeping dry on the pool deck. The pool test attracted some attention from the lifeguard, but all was well. The sub however didn't behave as desired. After some initial nice runs, the power was lost because the CA gave way under the torque of the water / vibrations of the shaft and perhaps other factors.
Pictures of the configuration and testing prior to the pool trial.
Pictures of the sub in a box and pool trials.
Some fun videos!
May 29, 2009 Now We're Cookin'!
May 28, 2009 Powered Sub in the Water!
May 27, 2009 Late Night Home Depot Trip! Another HD run resulted in the purchase of some plastic chicken coup wire from the lawn & garden section. This is for the base of the frame. I cut out a few sections to perhaps layer it in different orientations. But I settled for the single layer for now (shown). Used tin shears to cut the segments and t-square and sharpie to measure and guide cuts. Also on this trip I purchased copper 1" pipe holders. This is different from the larger stainless steel pieces I dealt with earlier in the week (on Memorial Day). They were too big to hold the film canister... I was in too much of a hurry post trip to Arlington Cemetery to obtain the proper dimensions and relied instead on memory. I also received the first batch of thrusters and Ethernet (tether) wire from Jameco today.
May 25, 2009 Control Box (Happy Memorial Day) Continued work with the control box and made several changes to the setup. Removed the blade fuse holder from the outside and moved the fuse holder inside replacing it with the cylindrical type. I already had leftover cylindrical fuses from the Squidlian project. I also started mounting the DPDT switches for testing. The images here however show the blade fuse holder still in place externally connected with a wire nut. The fuse holder itself was surprisingly heavy (relatively) and resulted in an awkward feel when holding the control box.
May 24, 2009 Control Box Continued work with the control box parts image shows one of the DPDT switches in a vice prepared for soldering. And Angela got me a hot glue gun from Michael's and some glue sticks!
May 23, 2009 Frame Construction Finished drilling all joins w/ 3/32" bit. used 1/4" bit for water drainage locations (initially 5) to flood structure and displace air. This makes the structure no-longer buoyant. The #6 screws were installed on one side of the joints as two side installation seemed insane. The biggest difficulty was the interplaner connections for drilling to assemble and disassemble the pieces to maintain a good fit. These cross sections had to be continually fiddled with the other sections to assure good alignment and fit. The red sharpie marks were very useful.
May 22, 2009 Frame Construction Started drilling holes for Inky's frame construction. Noted 1/8" too big per directions & standard bit in The drilled locations > 1/8". Used 3/32" bit with electrical tape in Dremel drill press for drill. Worked with recommended #6 x 1/2" pan head sheet metal screws (zinc). Used a red sharpie marker to mark both the rotation and depth of the various placements for the relative position of the pieces. This assisted in assuring a good fit when the parts were disassembled and drilled in segments. Segments were assembled in sections and then removed as a whole or sometimes disassembled again for drilling of the next segments. The left side was a good start. Then the right side. Then the front section involved removing part from the left and right section for its assembly. Next the rear cross bar was a bit more difficult due to its position, but also managed with assembly / disassembly techniques.
May 21, 2009 Wiring Soldered blade fuse holder outside the control box & also cannibalized my DC power inverter (used in the car's cigarette lighter to power my laptop) spare cables to hook up to a battery. The clamps were ideal and heavy gauge wire to be used to connect to a power source, so I cut off the end connectors and soldered the wire to the fuse holder (hot side) and ran the ground internal. Installed and tested the SPST switch using 3 of the 2800 mA-hr 12VDC lead batteries from the Squidlian project and using a 40 amp blade fuse I had laying around (this needs fixed... clearly).
I also noticed a safety issue with the soldering and taping job done on the fuse connector to the clamps. The wire is too thick so it punches through the electrical tape. I should buy a heat gun. Also on the clamp side, those are useful and I should get another set or two for other projects.
May 20, 2009 Project's First RadioShack Run It was inevitable, RadioShack is just too convenient. Purchased 3 - DPDT switches to control each thruster, 1 lighted SPDT switch for on/off, and a couple different types of fuse holder (blade & cylindrical). Started drilling out control box parts and soldering DPDT switch wires. Cannibalized my old Klipsch computer speaker wires for red / black light wiring.
May 19, 2009 E-bay... Duh! Recommended by a co-worker to take a look at e-bay auctions for film canisters... I should fix my PayPal and E-bay accounts I suppose. Not much work tonight went to see the Pirate beat the Nationals in the 10th inning with some of the best coaching I've ever seen unfold. This was of course following some massive drama about where my tickets were that I bought from a co-worker the previous day. They were inside my laptop... the closed laptop that was hooked up to my desktop station...
May 18, 2009 Calling All Film Canisters! Began a search for film canisters over Facebook...
May 15, 2009 First Snag! In all my brilliance I did not notice that some of the connectors where threaded... so back they went to HD and I came home to finish cutting pieces for Blinky and Clyde.
May 14, 2009 Project Inky is underway! Home Depot run using the new Tuscon to transport the 10' length of 1/2" ID Sch. 40 PVC pipe, 90 deg elbows, and T-sections.
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Copyright 2009, Justin S. McFarland. All Rights Reserved. |
