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Quick conversion from ROV to Crawler


(Todd Sparkes) #1

Hello all,
I am building a wheeled transporter to be able to inspect the inside of pipelines and other assets.
The frame I am building has 4 each of 12v DC planetary motors for wheel drivers. My question is can I simply install plugs on the current thruster cables and then be able to quickly swap from ROV with thrusters to crawler with wheels?
In theory it is simply to remove the electronics enclosure from one frame and mount it on a different frame. This would allow me to use all electronics and software that I use for the ROV.
Ideally current draw would be a lot less on the ESCs so I am hoping this can be done without issue? Any thoughts?
One more question. I am planning to use a motor encoder to allow me to count wheel revolutions to measure distance traveled. As most inspections would be underground the GPS will not be reliable the same as in water. Using PI or Arduino can I read the encoder, output data as a number then run it through a Minim OSD to give me a reading on the surface display? Or is there an easier method to read the encoder output?
Thanks for taking the time to read this.


(Etienne Demers) #2

Hi Todd,

Need to know exactly which motor you are using in order to have an idea. Are they BLDC?

Cheers,
E.


(Todd Sparkes) #3

Hey Etienne,
How are you.
The motors are Brushed DC.
• 12VDC
• Reduction Ratio: 1:51
• Right Angle Spiral Bevel Gearbox Ratio: 1:1 (reversible and allows back drive)
• Rated Torque: 2.8 kgf-cm
• Rated Speed: 116 RPM
• No Load Current: < 150mA


(Etienne Demers) #4

Are they they wired into one single winding? (You put 12VDC on it to turn it one way and then reverse polarity to have it go the other way?)


(Todd Sparkes) #5

Yes they are a single winding.


(Rusty) #6

Hi Todd,

You can use those motors but you’ll have to use brushed ESCs instead of brushless ESCs. There are several from Pololu and other places that take in a standard PWM signal and would be plug and play replacements for the ones on the ROV.

The wheel encoders could be read by a second microcontroller or by the Pixhawk with some work. I would look into ArduRover and their forums and see if anyone has done this.

-Rusty


(Etienne Demers) #7

The BR thrusters are BLDC motors. This is like a 3 AC phase motor. You will need to replace the controllers with one that can take the PWM and spit out ±DC. or change your motors to be bldc.