Convert OpenROV 2.8 to Blue Robotics M100 brushless motors


#1

Hi All,

Blue Robotics (BR) used to sell a kit to adapt their T100 Thrusters and M100 brushless motors to the OpenROV 2.7 and earlier versions. Since I love a challenge, I decided to see if I could adapt the BR M100 motors to both the horizontal and vertical motor positions on the OpenROV 2.8. It turns out it can be done with a little drilling and reaming.

BR used an adapter to mount the vertical motor on the OpenROV 2.7 chassis and the adapter can still be used to mount the BR M100 motor on the 2.8 chassis by drilling two additional holes in the vertical motor mount. Below is a picture of the modified vertical motor mount:


The three holes closest to the “T” are the original holes and the two holes farthest from the “T” are the additional two holes used to mount the motor adapter along with the hole at the top of the “T”. The two additional holes are the same diameter as the original hole at the top of the “T”.

To mount the M100 motors at the same horizontal locations as the DST-700 I found that I did not need to use the motor adapter used to mount the vertical M100 motor and could mount the M100 motor directly on the Vertical Motor Mount structure. Below is a picture of the modified Vertical Motor Mount structure:


To mount the M100 motor directly on the Vertical Motor Mount structure I had to open up the original motor mount center hole to a diameter of 0.450 inches and the two adjacent horizontal mounting holes on either side of the center hole to a diameter of 0.149 inches to provide clearance for the two M3X12 mm stainless steel hex machine screws used to attach the M100 motor to the Vertical Motor Mount structure.

Once I get the Vertical Motor Mount structure assembled, I will provide pictures of the M100 motors in the vertical and horizontal motor mount positions.

Regards,
TCIII AVD


Thrusters / Motors
Gettings Started build ROV
#2

Thanks for the information. When I finish the Rover 1, (a very compact unit) I hope to build a box unit with 6 thrusters and plan to look at the Blue Robotics motors for that unit.


#3

Hi All,

I got the Main Structure assembled this morning and mounted the Vertical M100 motor on the Horizontal Motor Mount and Horizontal M100 motors on the Vertical Motor Mount structure. The pictures below show how clean the motor conversion came out:


Front View showing the rears of the M100 Horizontal motors and a front view of the M100 Vertical motor, motor mount, and propeller.

Rear view showing the Horizontal thrusters’ propellers and a rear view of the M100 Vertical motor, motor mount, and propeller.

Top View showing the top of Vertical motor propeller

Bottom view showing the two M100 Horizontal motors and propellers and the bottom of the Vertical M100 motor mount.

The M100 motors have three exposed solder pads for the motor phase windings so I plan to use leftover 22 gauge wire to provide the connections from the pads to the their respective ESC wires in the wire harness. I will then pot the exposed solder pads with epoxy to waterproof them.

The M100 motors weigh 225 grams more than the original DST-700 motors so the stern of the Frame is going to try to roll back about the center of mass. Hopefully using bigger fishing sinkers might compensate for the increased weight, however I may have to add some buoyancy to maintain close to neutral buoyancy. Only testing in my test tank will tell.

More to come.

Regards,
TCIII AVD


#4

@TCIII - Very nice work on this! It’s looking very good.

I’m curious to see how the slightly heavier weight of the M100s will affect the weight and balance of the ROV. It seems to be pretty sensitive to added weight. You might need to add a bit of buoyancy at the back to counter that.

Keep it up.


#5

@Rustom_Jehangir,
Thanks for the kudos, much appreciated.
Yes, I may have to add a bit of buoyancy at the rear as others have had to do when using two of the BR T100 Thrusters to replace the two DST-700 motors. Though a heavier fishing weight in place of the 3 oz lead sinker might help to keep the fame horizontal, but I could lose the neutral buoyancy. As I said before, only testing in my 38 gallon test tank will let me view frame buoyancy and trim.
Regards,
TCIII AVD


#6

Hi All,
I have completed attaching the wire harness to the BR M100 motors and am now ready to attach the battery tubes.
The pictures below show how I attached the M100 motors to the wire harness:


Head On View

Raised View

More to come.

Regards,
TCIII AVD


#7

Hi All,

I got the OROV chassis finished to the point that I could attach the 2.8 Controller Board to the Pass-Through DB25 connector, load the batteries and talk to the Cockpit. The M100 motors worked fine in air as I blipped them and everything else is functional. This Controller Board has the Pro Camera-HD Upgrade.

More to come.

Regards,
TCIII AVD


#8

Hi All,

This project unfortunately got waylaid by a move to a new home location and the replacement of both of my hips due to arthritis.

I finally got the chassis put together and then put the ROV in a test tank to determine its present buoyancy. Since the BR M100 motors are collectively about 225 mg heavier than the stock brushless motors, I had to replace the 3 oz weights on the arms of the ROV with 1 oz weights and add two pieces of syntactic foam (3.5" x 2.5" x 1") to both sides of the stern of the ROV along with a centered 3 oz weight to give the ROV the right amount of buoyancy.

The top of the ROV now rests just slightly below the surface, is easily pushed down by hand and returns slowly to the surface when released.

The following pictures should give an idea of the final ROV configuration:


Stern view showing the syntactic foam blocks, M100 motors/propellers, 3 oz weight, and tether attachment.


Top view showing BR M100 vertical motor and propeller.


Forward view showing Pro Camera-HD Upgrade/Control Electronics and optional LED lights.

Regards,
TCIII AVD


#9

Hi All,

I ran the OpenROV2.8/M100 this weekend in a swimming pool and found it to be extremely fast and maneuverable even on a motor setting of 1. I really had to use a joystick to get proportional control of the motors as just blipping the keyboard motor direction controls resulted in poor directional control.

When moving in reverse I found that the thrust from the two horizontal M100 motors would cause the ROV to try and sink unless I was very judicious with the reverse motor speed. This is because the thrust from the horizontal motors was being deflected upwards through the two holes in the top of the chassis by the back of the Camera/Electronic Control WTC.

All in all I think that this is a very worthwhile modification if you are planning on building an OROV2,8 from the bottom up. To try and modify a completed OROV2.8 might be difficult as drilling the necessary holes for the vertical motor mount and the horizontal motor mounts might be very difficult on a completed chassis.

Regards,
TCIII AVD