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VBox R/C Boat for Autonomous Offshore Competition

Posted by Thomas J Coyle III on January 23, 2015 at 8:14am

Hi All,

If you have been reading my posts on the Comment Wall you are aware that I am building a fairly large R/C racing boat for autonomous offshore competition.

The R/C boat I have selected is the Zippkit VBox 2013 edition that is 46" long and 17" in beam. The boat is normally powered by a 26cc gas engine of around 5 - 7 hp, however I plan to use a brushless electric motor in place of the gas engine.

Since I do not need speeds of 50 - 60 mph for the kind of competition that I envision, I feel that a brushless electric motor of around 3 hp will be sufficient to drive the boat at around 25 - 30 mph. Therefore I have identified a Leopard 5692 1000kva 3000 watt 56 mm dia brushless motor as being a suitable candidate for my purposes.

I have decided on using twin 6S 10,000mahr LiPo batteries in parallel to power the motor. So now I am researching high current, water cooled ESCs with 180 - 220 amp capacity to control the motor.

After the propulsion and steering hardware have been installed in the hull, I plan to integrate a Pixhawk navigation controller and associated components into the hull to provide autonomous navigation.

I will begin the Project Discussion with the installation of the propulsion and steering hardware and then move on to the integration of the navigation controller platform.

Regards,

TCIII AVD    

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Tags: etti, leopard, vbox, zippkits, autonomous, brushless, motor
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  • Admin
    Thomas J Coyle III April 21, 2015 at 4:55pm

    Hi All,

    The GPS/Compass Module, 915MHz Telemetry Radio, and some miscellaneous cables arrived on Monday and the Pixhawk and PPM Encoder arrived today.

    On Monday I laid out the navigation controller plate and attached a vertical panel 2.5 inches tall to one side of the controller plate to mount the Spektrum AR7000 receiver, remote receiver and PPM Encoder. I then proceeded to mount the GPS/Compass pedestal near the rear of the controller plate to keep it as far from the Leopard brushless motor as possible and fabricated a mount for the Power Module and mounted it on the side of the controller plate opposite the receiver/encoder panel. A mount for the  915MHz Telemetry Radio was fabricated next to raise the radio about 3 inches above and close to the front end of the controller plate so that I could cut a hole in the front of the controller plate watertight cover to screw in the radio antenna.

    Since I did not have the Pixhawk and PPM Encoder yet, I employed a spare APM2.6, loaded with ArduRover v2.46, that I had on the shelf to test the GPS/Compass Module, Telemetry Radio, and Power Module. While attached to my PC with the USB cable I used MP to verify that the GPS/Compass Module were functional. I then attached a  915MHz Telemetry Radio ground station to the PC and powered the APM by battery through the PM and verified that the 915MHz Telemetry Radio was functional. So far so good.

    Today, after receiving the Pixhawk and PPM Encoder, I attached the  Spektrum AR7000 receiver, remote receiver and PPM Encoder to the vertical panel and fabricated a small sub plate to mount the Pixhawk on the navigation controller plate. I then connected all of the components together and proceed to load ArduRover v2.49 onto the Pixhawk.

    3701986545?profile=originalNavigation Controller Top View

    3701986579?profile=originalNavigation Controller Front View

    As can be seen in the picture above, I still have to mount the speaker and the arming switch on the controller chassis.

    At first MP had trouble trying to connect to the Pixhawk to load the firmware so I used the FMU reset button instead of removing the power to the Pixhawk to reboot the Pixhawk and that did the trick. The Pixhawk appeared to function correctly and the GPS/Compass Module was observed to be working correctly also. I then calibrated the R/C transmitter using the MP Radio Calibration screen.

    The final step was to power the Pixhawk with the battery to be able to calibrate the Compass and to check the functionality of the 915MHz Telemetry Radio. Upon powering up the MP made connection with the Pixhawk through the Telemetry Radio so I proceeded to calibrate the Compass and setup the Mode Control for Manual, Learning, and Auto. I still have to conduct an accelerometer calibration to complete the setup of the navigation controller.

    My assistant, the wife, will be back tomorrow with the family camera so I will have her take a few pictures of the layout of the navigation controller and where it will mount on the VBox deck.

    3701986600?profile=originalNavigation Controller Deck Plate

    3701986446?profile=originalNavigation Controller with Water Resistant Enclosure

    Regards,

    Tom C AVD

    • Developer
      Grant Morphett > Thomas J Coyle III April 26, 2015 at 4:29pm

      That is an extremely impressive build Tom.  I can't wait to see a video of it in action.

      One note - the 3DR Power Module only goes up to 18v i.e. 4S so you won't be able to use it in your 6S setup.  However HobbyKing do sell a 10S one which ardupilot supports.

      http://www.hobbyking.com/hobbyking/store/__56855__HKPilot_Mega_10s_...

      Another option is the AttoPilot module

      https://www.sparkfun.com/products/10644

      See the wiki page for info

      http://plane.ardupilot.com/wiki/common-optional-hardware/common-pow...

      Note that our CanberraUAV team has purchased some HK ones to use in our TradHeli that we are testing with for the next OBC in 2016.

      Further, if you had 2 power modules I think we can connect both to the pixhawk and monitor each battery separately.  A quick look at the parameters tells me the code can do a second power module however I can't see any info on how to wire it up.  I've never done it myself but I'll see if I can put some info together on the wiki on how to do this.

      Thanks, Grant.

    • Admin
      Thomas J Coyle III > Grant Morphett April 26, 2015 at 6:20pm

      @Grant,

      Thanks for the kudos, much appreciated.

      The navigation controller board will be powered by its own 3S 2200 mahr battery.

      Since the Hifei ESC is presently powered by two 6S 5000mahr they will be supplying approximately 60 amps each at full throttle. My main concern will be the run time before the ESC goes into hard cutoff at 3.0 vdc/cell. The ESC will actually cutoff at more than 3.3vdc to protect the batteries. Hard cutoffs are set at 3.0vdc while soft cutoffs are set at 3.3vdc.

      The ESC has a data logging feature that I plan to use to see what the current consumption and battery voltage looks like over a typical course at different speeds. This will allow me to determine how long I can run before having to recharge the batteries before making another run. I could also put in LiPo battery monitor that would be visible on the deck to allow me to quickly see how much battery life is left prior to each circuit of the course.

      What would be most helpful would be to provide a way to use either the Pixhawk ADC 3.3vdc or 6.6vdc converters to monitor a battery scaled voltage monitoring circuit whose output could be sent back in the MavLink telemetry.

      Regards,

      Tom C AVD 

    • Developer
      Grant Morphett > Thomas J Coyle III April 30, 2015 at 6:14pm

      Hi Tom.  You can do exactly what your after re the ADC 3.3 or ADC 6.6 for voltage monitoring.  If you have a look at the BATT_2_ parameters on

      http://rover.ardupilot.com/wiki/apmrover2-parameters/#battery_monit...

      they are slightly incorrect (I'll fix them up soon).  You can use ANY analogue pin to measure input voltage.  So for instance if you hooked your voltage up the 6.6v ADC which is pin 15 on the pixhawk then you would set BATT_2_VOLT_PIN = 15 and this data would automatically get sent back to the ground station and displayed (assuming the ground station supports the second battery data).  You would need to set some of the other BATT_2 parameters as well.

      Now you will need a voltage divider to ensure the correct voltage range is supplied to the ADC.  So 6.6v would be a full battery and then dropping down from there.  I'm not the expert in this area however this page is very helpful

      https://learn.sparkfun.com/tutorials/voltage-dividers

      Thanks, Grant.

    • Admin
      Thomas J Coyle III > Grant Morphett April 30, 2015 at 8:15pm

      Hi Grant,

      Thanks for the great information, much appreciated.

      I will give it a look and setup what is necessary to measure my battery voltage.

      Regards,

      Tom C AVD

  • Admin
    Thomas J Coyle III April 18, 2015 at 12:43pm

    Hi All,

    Things have been at a standstill since I last posted.

    I have been waiting on a Pixhawk, GPS/Compass, and other assorted components to be shipped from 3DR. I received a shipping notice on Friday that the products I had ordered had been shipped and that they will be delivered on Tuesday of this coming week. This will allow me to layout and assemble the navigation controller on the VBox hull starting on Tuesday afternoon.

    In the meantime I would have put the VBox hull in the Association's mini lake and used just my R/C transmitter and receiver to test out its performance. Unfortunately my assistance, the wife, had to accompany her Mother back north for the summer and was not available to assist me in getting the hull in the water. She will be back in town this coming Wednesday so I might be able to test out the VBox hull with just the R/C radio this coming weekend.

    All for now.

    Regards,

    Tom C AVD

    • Hernan Gabriel > Thomas J Coyle III April 18, 2015 at 4:36pm

      Lovely project. 

      Do you know where can I get this plan to build that boat? probably a similar one can work too.... 

      Awesome updates... keep going! 

      Hernan.

    • Admin
      Thomas J Coyle III > Hernan Gabriel April 18, 2015 at 4:43pm

      @Hernan,

      Thanks for the kudos, much appreciated.

      The VBox Crackerbox 2013 Edition comes as a kit and I doubt that you can try and build it from plans for cheaper than the basic kit cost Link 

      Regards,

      TCIII AVD

  • Admin
    Thomas J Coyle III April 4, 2015 at 12:09pm

    Hi All,

    Well, the 6S 5000mahr HK LiPo batteries arrived on Thursday so I decided to make up a set of battery cables to go from each battery (port and starboard locations) to the parallel battery connection circuit board that is attached to the ESC battery input.

    The wire on the HK battery says 10 AWG and is connected to a 4mm bullet connector plug. When I tried to build matching 4mm bullet connector plugs it turned out that my 10AWG cables were too big in diameter to allow the 4mm bullet connectors to lock into their respective housings.

    Searching the internet I found that the Eflite EC5 battery/ESC connectors would handle up to 120 amps and are easy to engage and disengage. The local RC hobby shop had them in stock so I purchased two sets of male/female and individual male and individual female EC5 connectors. I will use the individual male connectors to build battery charging adapters for my LiPo battery charger. I have built two battery interconnection cables out of male EC5 connectors and 10AWG silicone cable that will connect the batteries to the parallel battery connection circuit board. 

    In the meantime I had charged and discharged one of the HK LiPo batteries and found that all the cells were within 0.01v when the battery was full charged. I then charged and discharged the other LiPo battery and found that it followed suit with the first battery. Nothing like consistency:-)

    I have attached a female EC5 battery connector to one of the LiPo batteries and will do the same with the second LiPo battery once it has been discharged to storage level.

    As far as the navigation platform is concerned, the 3DR store is backordered on the Pixhawk and the PPM Encoder. However the GPS/Compass module and the individual 915MHz Telemetry Radios are available for purchase and I do have a spare APM2.6 on the shelf that I can substitute for the Pixhawk until it and the PPM Encoder become available.

    3701974071?profile=originalESC and Parallel Battery Circuit Board

    3701973888?profile=originalHK 6S 5000mahr LiPo Battery

    3701974094?profile=originalBattery to Parallel Battery Circuit Board Interconnect Cable

    Regards,

    Tom C AVD

    • T3
      Richard Boyhan > Thomas J Coyle III April 6, 2015 at 12:37pm

      Hi Tom,

      You're boat is coming along nicely.  Sure is a lot of work!  Great work on the finish.  Where do you plan to test it?

      Regards,
      Richard

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