Hi All,
I have some good news concerning the Battery Compartment WTC vacuum testing.
Up until yesterday the Battery Compartment WTC vacuum testing was being conducted with just blank cable penetrators as I was trying to ascertain the source of a 20 mm Hg/hour vacuum leak. Once I determined the source of the leak, which was due to the original universal cutoff ball valve, and installed a better quality ball valve designed for air compressors and vacuum pumps, I was ready to retest the Battery Compartment WTC with the actual T100 Thruster ESC power cable penetrators installed in the WTC End Cap.
I started by removing four of the blank cable penetrators and then cleaning the End Cap surface where each cable penetrator would mount and cleaning and re-lubing the O ring seal on each penetrator. I then installed the four T100 Thruster ESC power cable penetrators into their respective End Cap holes.
After verifying that all of the ESC power cable and blank cable penetrators were properly seated, I proceeded to pump down the Battery Compartment WTC to 560 mm Hg with the vacuum pump and then closed the cutoff ball valve to isolate the WTC from the vacuum pump. After waiting an hour I started the vacuum pump to bring the vacuum gauge back to 560 mm Hg and then opened the cutoff ball valve. Much to my relief the vacuum gauge did not move off of the 560 mm Hg mark indicating that the WTC had held the 560 mm Hg vacuum without leaking.
The fact that the installation of the ESC power cable penetrators in place of the blank cable penetrators did not result in any change in the ability of the WTC to hold a 560 mm Hg vacuum over the same one hour period as the blank cable penetrators indicates that the Blue Robotics cable potting process results in leak free cable penetrations into the Battery Compartment WTC.
I will measure the Battery Compartment WTC vacuum tomorrow after letting it sit overnight to see if there is any vacuum loss between this afternoon and tomorrow morning which will be around 20 hours.
This morning I again measured the vacuum level in the Battery Compartment WTC and found the level had dropped by only 20 mm Hg (1 mm Hg/hour) which was the same level loss after 20 hours when using the blank cable penetrators. Therefore I feel comfortable concluding that the 20 mm Hg vacuum loss over the 20 hours is probably due to my vacuum test setup and not the cable penetrators in the WTC End Cap.
Now I will move on to installing the ESC Signal cable penetrators in the Navigation Controller WTC End Cap and perform the same one hour and 20 hour vacuum leak test on that WTC.
More to come.
Regards,
SSN626B/TCIII
Experimental ROV Design using Blue Robotics Components
Re: Experimental ROV Design using Blue Robotics Components
Last edited by SSN626B on Oct 25th, 2015, 4:07 pm, edited 1 time in total.
Re: Experimental ROV Design using Blue Robotics Components
Hi All,
While I was cleaning the grooves on one of the Navigation Controller WTC End Cap O ring Flanges I discovered a very small nick (scratch) in the bottom of the second from the front O ring groove.
The nick (scratch) is probably 0.005 - 0.010 inch deep and about 0.125 inch long and is perpendicular to the circumference of the O ring groove. I discovered it because it was deep enough to cause the Q tip that I was using to clean the O ring groove to catch on it and stop.
Since it is in the second from the front O ring groove, it may not be a problem as the first O ring seal may be able to maintain the water tight seal. However if I cannot maintain the same vacuum loss over time (1 mm/hour) that I did with the Battery Compartment WTC, it might be wise to replace the O ring Flange as a safety precaution assuming the cable penetrators are not leaking also.
After completing the assembly of the Navigation Compartment WTC I opened the cutoff ball valve and commenced to pump down the WTC to 560 mm Hg. After waiting an hour I started the vacuum pump, pumped down the vacuum gauge tubing circuit to 560 mm Hg and then opened the cutoff ball valve to the WTC. Much to my relief the gauge did not move indicating that the Navigation Controller WTC was holding the same vacuum level over the same period of time as the Battery Compartment WTC. So it presently looks like the nick in the bottom of the second O ring groove has not had an impact on the WTC's vacuum seal (water tight) capabilities.
I then made sure the Navigation Controller WTC vacuum was still at 560 mm Hg, closed the cutoff ball valve for a second time and waited two hours before measuring the vacuum level in the WTC. Again, much to my relief the WTC's vacuum level was still at 560 mm Hg. After closing the cutoff ball valve for the third time, I plan to wait approximately 20 hours before measuring the WTC's vacuum level again. If I measure a value of around 540 mm Hg, as I did with the Battery Compartment WTC after waiting 20 hours, then I am pretty confident that it is my clunky test setup that is leaking, probably at the cutoff ball valve, and not a leak in the WTC.
Navigation Controller Vacuum Leak Test Setup
Once I have completed the WTC vacuum checks, I will attach the ESC Power cables to the Power Junction Board battery cables and prepare to install the two 3S 5000 mah LiPo batteries and associated power cable connectors. This will be followed by installing the ESC Signal Junction Board on the Navigation Controller platform, attaching the ESC Signal cables to the Signal Junction Board, and then installing the ROV bottom side controller board and associated signal and power cables.
More to come.
Regards,
Tom C AVD
While I was cleaning the grooves on one of the Navigation Controller WTC End Cap O ring Flanges I discovered a very small nick (scratch) in the bottom of the second from the front O ring groove.
The nick (scratch) is probably 0.005 - 0.010 inch deep and about 0.125 inch long and is perpendicular to the circumference of the O ring groove. I discovered it because it was deep enough to cause the Q tip that I was using to clean the O ring groove to catch on it and stop.
Since it is in the second from the front O ring groove, it may not be a problem as the first O ring seal may be able to maintain the water tight seal. However if I cannot maintain the same vacuum loss over time (1 mm/hour) that I did with the Battery Compartment WTC, it might be wise to replace the O ring Flange as a safety precaution assuming the cable penetrators are not leaking also.
After completing the assembly of the Navigation Compartment WTC I opened the cutoff ball valve and commenced to pump down the WTC to 560 mm Hg. After waiting an hour I started the vacuum pump, pumped down the vacuum gauge tubing circuit to 560 mm Hg and then opened the cutoff ball valve to the WTC. Much to my relief the gauge did not move indicating that the Navigation Controller WTC was holding the same vacuum level over the same period of time as the Battery Compartment WTC. So it presently looks like the nick in the bottom of the second O ring groove has not had an impact on the WTC's vacuum seal (water tight) capabilities.
I then made sure the Navigation Controller WTC vacuum was still at 560 mm Hg, closed the cutoff ball valve for a second time and waited two hours before measuring the vacuum level in the WTC. Again, much to my relief the WTC's vacuum level was still at 560 mm Hg. After closing the cutoff ball valve for the third time, I plan to wait approximately 20 hours before measuring the WTC's vacuum level again. If I measure a value of around 540 mm Hg, as I did with the Battery Compartment WTC after waiting 20 hours, then I am pretty confident that it is my clunky test setup that is leaking, probably at the cutoff ball valve, and not a leak in the WTC.
Navigation Controller Vacuum Leak Test Setup
Once I have completed the WTC vacuum checks, I will attach the ESC Power cables to the Power Junction Board battery cables and prepare to install the two 3S 5000 mah LiPo batteries and associated power cable connectors. This will be followed by installing the ESC Signal Junction Board on the Navigation Controller platform, attaching the ESC Signal cables to the Signal Junction Board, and then installing the ROV bottom side controller board and associated signal and power cables.
More to come.
Regards,
Tom C AVD
Re: Experimental ROV Design using Blue Robotics Components
Hi All,
Good news! After waiting approximately 20 hours before measuring the Navigation Controller WTC's vacuum level again, I measured a value of around 540 mm Hg, as I did with the Battery Compartment WTC after waiting 20 hours. Therefore I am pretty confident that it is my clunky test setup that is leaking, probably at the cutoff ball valve, and not a leak in the WTC.
Regards,
SSN626B/TCIII
Good news! After waiting approximately 20 hours before measuring the Navigation Controller WTC's vacuum level again, I measured a value of around 540 mm Hg, as I did with the Battery Compartment WTC after waiting 20 hours. Therefore I am pretty confident that it is my clunky test setup that is leaking, probably at the cutoff ball valve, and not a leak in the WTC.
Regards,
SSN626B/TCIII
Re: Experimental ROV Design using Blue Robotics Components
Hi All,
Today I received two more Blue Robotics T100 Thrusters with built-in ESCs so I decided to fabricate and install the mounting platforms for the two additional Thrusters.
The two mounting platforms are identical to the two cantilevered platforms that support the two rear horizontal Thrusters. The two platforms were originally attached to a horizontal transverse support in the very front of the ROV, but the support blocked easy access to the Battery Compartment WTC front End Cap. The two cantilevered support platforms will be mounted 5 3/4" from the top of the ROV which will place the centerline of the Thrusters in the middle of the cutouts in the top portion of the ROV side panels. The two rear cantilevered platforms will be raised from their current position to the same height from the top as the front support platforms.
The two rear Thrusters will be mounted on their support platforms at a 45 degree angle from the ROV horizontal center line while the two front Thrusters will be mounted on their support platforms at a 135 degree angle from the ROV horizontal center line. This mounting configuration will provide vectored thrust from the four Thrusters and allow the ROV to move laterally as well as forward and backwards.
More to come.
Regards,
SSN626B/TCIII
Today I received two more Blue Robotics T100 Thrusters with built-in ESCs so I decided to fabricate and install the mounting platforms for the two additional Thrusters.
The two mounting platforms are identical to the two cantilevered platforms that support the two rear horizontal Thrusters. The two platforms were originally attached to a horizontal transverse support in the very front of the ROV, but the support blocked easy access to the Battery Compartment WTC front End Cap. The two cantilevered support platforms will be mounted 5 3/4" from the top of the ROV which will place the centerline of the Thrusters in the middle of the cutouts in the top portion of the ROV side panels. The two rear cantilevered platforms will be raised from their current position to the same height from the top as the front support platforms.
The two rear Thrusters will be mounted on their support platforms at a 45 degree angle from the ROV horizontal center line while the two front Thrusters will be mounted on their support platforms at a 135 degree angle from the ROV horizontal center line. This mounting configuration will provide vectored thrust from the four Thrusters and allow the ROV to move laterally as well as forward and backwards.
More to come.
Regards,
SSN626B/TCIII
Re: Experimental ROV Design using Blue Robotics Components
Hi All,
Today I got the two forward horizontal Thruster cantilevered mounting platforms attached to the inside front of the ROV chassis. I also fabricated the sub plates that attach each Thruster to the mounting platforms at a 45 degree angle to the ROV horizontal centerline for vectored thrust operation.
Tomorrow I will move the rear two Thrusters up to the same height from the top of the ROV that the forward Thrusters are located at and angle each rear Thruster at a 45 degree angle.
I should have the Thruster mounting completed by tomorrow afternoon and will shoot some pictures of the new Thruster front and rear mounting positions.
More to come.
Regards,
SSN626B/TCIII
Today I got the two forward horizontal Thruster cantilevered mounting platforms attached to the inside front of the ROV chassis. I also fabricated the sub plates that attach each Thruster to the mounting platforms at a 45 degree angle to the ROV horizontal centerline for vectored thrust operation.
Tomorrow I will move the rear two Thrusters up to the same height from the top of the ROV that the forward Thrusters are located at and angle each rear Thruster at a 45 degree angle.
I should have the Thruster mounting completed by tomorrow afternoon and will shoot some pictures of the new Thruster front and rear mounting positions.
More to come.
Regards,
SSN626B/TCIII
Re: Experimental ROV Design using Blue Robotics Components
Hi All,
This morning I got side tracked by a "honeydo" project so I did not get to finishing the installation of the front Thruster support platforms until this afternoon. I completed adding holes to the front Thruster sub mounting plates so I can attach the sub mounting plates to the two cantilevered support platforms with 3/4" 4-40 ss flat head screws. The completed front Thruster cantilevered support platforms with the T100 Thrusters attached to the sub mounting plates can be seen in the following picture:
Front Thrusters attached to cantilevered Mounting Platforms
The front mounted Thrusters are mounted on the sub mounting plates at 45 degree angles to provide a vectored thrust configuration. The front Thrusters can move water freely forward and backwards through the front of the ROV and the forward windows cut in the ROV chassis side plates.
I will move the rear Thrusters up to the same height from the top of the ROV chassis as I have mounted the front Thrusters which will center them horizontally in the middle of the rear ROV chassis windows. The following is a picture of the present mounting locations of the rear Thrusters:
Rear Thrusters present mounting configuration
The rear Thruster cantilevered mounting platforms will be raised to a position that is 5 1/2" from the top of the ROV chassis. Since the mounting platforms already have 10-24 threaded screw holes in them I made two drill templates, one for each mounting platform, that I will use to drill three mounting holes on each side of the ROV chassis plates. Then all I have to do is remove the sub mounting platforms, turn the Thrusters to the required 45 degree angles, reattach the sub mounting platforms to the cantilevered mounting platforms, and then attach the cantilevered mounting platforms to the sides of the ROV chassis plates using the new mounting holes that I previously drilled in the ROV chassis plates.
More to come.
Regards,
SSN626B/TCIII
This morning I got side tracked by a "honeydo" project so I did not get to finishing the installation of the front Thruster support platforms until this afternoon. I completed adding holes to the front Thruster sub mounting plates so I can attach the sub mounting plates to the two cantilevered support platforms with 3/4" 4-40 ss flat head screws. The completed front Thruster cantilevered support platforms with the T100 Thrusters attached to the sub mounting plates can be seen in the following picture:
Front Thrusters attached to cantilevered Mounting Platforms
The front mounted Thrusters are mounted on the sub mounting plates at 45 degree angles to provide a vectored thrust configuration. The front Thrusters can move water freely forward and backwards through the front of the ROV and the forward windows cut in the ROV chassis side plates.
I will move the rear Thrusters up to the same height from the top of the ROV chassis as I have mounted the front Thrusters which will center them horizontally in the middle of the rear ROV chassis windows. The following is a picture of the present mounting locations of the rear Thrusters:
Rear Thrusters present mounting configuration
The rear Thruster cantilevered mounting platforms will be raised to a position that is 5 1/2" from the top of the ROV chassis. Since the mounting platforms already have 10-24 threaded screw holes in them I made two drill templates, one for each mounting platform, that I will use to drill three mounting holes on each side of the ROV chassis plates. Then all I have to do is remove the sub mounting platforms, turn the Thrusters to the required 45 degree angles, reattach the sub mounting platforms to the cantilevered mounting platforms, and then attach the cantilevered mounting platforms to the sides of the ROV chassis plates using the new mounting holes that I previously drilled in the ROV chassis plates.
More to come.
Regards,
SSN626B/TCIII
Re: Experimental ROV Design using Blue Robotics Components
Hi All,
Today I finished moving the rear Thrusters to their new position on the ROV chassis and angled both of the Thrusters at 45 degrees to the ROV longitudinal center line.
I had made a template of the three holes in each of the Thruster cantilevered mounting platforms so I could easily drill the mounting holes in their new location. After I finished moving the rear Thruster cantilevered mounting platforms, I removed each Thrusters sub mounting plate and moved each Thruster to a 45 degree angle to the ROV longitudinal center line.
The pictures that follow show the front and rear Thrusters in their new locations and also how I routed the front Thruster ESC power and signal cables from the front of the ROV back to rear of the Battery Compartment and Navigation Compartment WTCs:
Front Thrusters
Rear Thrusters in their new position on the ROV
Top of ROV Chassis showing the Front Thruster cable routing
Some of you observant members might notice that the rear pair of Thrusters are mounted with their nozzle exhausts point to the rear of the ROV chassis the same as the forward pair of Thrusters. As far as I can tell, by a search of the web for ROV Thrusters configurations, the Thrusters can be mounted as I have them configured or both the front and rear Thrusters can have their nozzle exhausts pointing to the outside of the front and rear of the ROV chassis depending on where the Thrusters are located on the chassis. The Blue Robotics T100 Thrusters provide a forward thrust of ~6 lbs. and a rearward thrust of ~4 lbs. at full power. Therefore with my configuration the lateral thrust provided by the front and rear Thrusters will be very similar and should not result in much torqueing about the ROV vertical axis during lateral movement.
Now I will have to measure the front Thruster power and signal cables and cut them to length so that they can be potted into their respective cable penetrators.
More later.
Regards,
SSN626B/TCIII
Today I finished moving the rear Thrusters to their new position on the ROV chassis and angled both of the Thrusters at 45 degrees to the ROV longitudinal center line.
I had made a template of the three holes in each of the Thruster cantilevered mounting platforms so I could easily drill the mounting holes in their new location. After I finished moving the rear Thruster cantilevered mounting platforms, I removed each Thrusters sub mounting plate and moved each Thruster to a 45 degree angle to the ROV longitudinal center line.
The pictures that follow show the front and rear Thrusters in their new locations and also how I routed the front Thruster ESC power and signal cables from the front of the ROV back to rear of the Battery Compartment and Navigation Compartment WTCs:
Front Thrusters
Rear Thrusters in their new position on the ROV
Top of ROV Chassis showing the Front Thruster cable routing
Some of you observant members might notice that the rear pair of Thrusters are mounted with their nozzle exhausts point to the rear of the ROV chassis the same as the forward pair of Thrusters. As far as I can tell, by a search of the web for ROV Thrusters configurations, the Thrusters can be mounted as I have them configured or both the front and rear Thrusters can have their nozzle exhausts pointing to the outside of the front and rear of the ROV chassis depending on where the Thrusters are located on the chassis. The Blue Robotics T100 Thrusters provide a forward thrust of ~6 lbs. and a rearward thrust of ~4 lbs. at full power. Therefore with my configuration the lateral thrust provided by the front and rear Thrusters will be very similar and should not result in much torqueing about the ROV vertical axis during lateral movement.
Now I will have to measure the front Thruster power and signal cables and cut them to length so that they can be potted into their respective cable penetrators.
More later.
Regards,
SSN626B/TCIII
Re: Experimental ROV Design using Blue Robotics Components
Looking good!
Though there are 2 small niggles with this configuration,
First, your Yaw/Heading, won't allow you to pivot on the spot, you'll travel slightly forward each time you try to pivot on the spot.
Second, Your lateral thrust probably won't induce much yaw, however (and possibly more annoyingly) the ROV will definitely move forward whilst trying to move laterally left or right.
both of these aren't the end of the world and can obviously be compensated for with software.
Though there are 2 small niggles with this configuration,
First, your Yaw/Heading, won't allow you to pivot on the spot, you'll travel slightly forward each time you try to pivot on the spot.
Second, Your lateral thrust probably won't induce much yaw, however (and possibly more annoyingly) the ROV will definitely move forward whilst trying to move laterally left or right.
both of these aren't the end of the world and can obviously be compensated for with software.
Re: Experimental ROV Design using Blue Robotics Components
Hi All,
Today I got kind of a late start so I just cut the Forward Thruster ESCs power and signal cables to length and prepared the cables and the cable penetrators for the potting process which I will do tomorrow morning. Performing the potting process in morning will give the marine grade epoxy the whole day to cure before I close up the shop to be able to put the car away.
Regards,
SSN626B/TCIII
Today I got kind of a late start so I just cut the Forward Thruster ESCs power and signal cables to length and prepared the cables and the cable penetrators for the potting process which I will do tomorrow morning. Performing the potting process in morning will give the marine grade epoxy the whole day to cure before I close up the shop to be able to put the car away.
Regards,
SSN626B/TCIII
Re: Experimental ROV Design using Blue Robotics Components
Hi All,
Today I potted the Forward Thrusters ESC power and signal cables into the front ends of their respective cable penetrators using the Blue Robotics recommended Loctite Marine epoxy. Tomorrow I will pot the WTC ends of each cable penetrator with the same marine grade epoxy.
As far as the Navigation Controller WTC goes, I still have to fabricate some type of cable to go from the six PWM inputs on the ESC Signal Junction Board to the onboard navigation controller six PWM output connectors.
Also, I still have to install the reverse impellers on three of the Thrusters to counteract the motor torque from their respective Thrusters on the opposite side of the ROV chassis.
More to come.
Regards,
SSN626B/TCIII
Today I potted the Forward Thrusters ESC power and signal cables into the front ends of their respective cable penetrators using the Blue Robotics recommended Loctite Marine epoxy. Tomorrow I will pot the WTC ends of each cable penetrator with the same marine grade epoxy.
As far as the Navigation Controller WTC goes, I still have to fabricate some type of cable to go from the six PWM inputs on the ESC Signal Junction Board to the onboard navigation controller six PWM output connectors.
Also, I still have to install the reverse impellers on three of the Thrusters to counteract the motor torque from their respective Thrusters on the opposite side of the ROV chassis.
More to come.
Regards,
SSN626B/TCIII