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Gripper arm electrical connection

I got hold of a gripper arm and it has open/close rotate left/rotate right functions, it works on 14-18v and has two wires for each of the main functions (and uses polarity switch )

Anybody have any ideas on how i could incorporate/ connect this gripper/manipulating arm into a BR2 ROV circuit board and control consul

thanks

Hey @Mac1 !

Maybe you could use a brushed ESC. They take a PWM and are able to switch polarity (1500us stops, lower goes one direction, higher goes the other one). Then you can just use the same control style we use in the newton gripper, using servoX_min/max_momentary.

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Hi murdo,

Willian asked me to draw up a quick schematic for you:


Using Aux pins 1 and 2, you should be able to control opening/closing with a joystick button mapped to servo1_max/min_momentary, and rotating left/right with a joystick button mapped to servo2_max/min_momentary. Momentary means that each press sends a short burst, which should help to provide relatively precise control over its movements.

Note that the example ESC that Willian linked to seems to only be rated to 2-3 LiPo batteries in series, and has a supply voltage range of 6-12.6V (at least according to the image), whereas the BlueROV2 uses a 4S battery (nominally 16V), and you’ve said your gripper requires 14-18V, which is the range for a 4S battery. Accordingly, you’ll likely need to find a different one that accepts the higher voltage level (it may help to search for something like brushed ESC 4S.

Without knowing which gripper you’re using and what it’s set up to do, we’re a bit concerned that you haven’t mentioned limits or end-stops. Assuming it is effectively just two DC motors, with no in-built limits to stop over-rotation or opening/closing beyond the limits of the mechanism, you’ll have to be quite careful when operating it to make sure you stay within its operating range.

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A post was merged into an existing topic: BluePrint Lab Alpha 3 Integration

Hello Eliot,
OK great thanks to you and Willian , I will order the parts and try , much appreciated

Hello Eliot, I have been looking at ESC 4s and they all seem to have 3 output wires/connections

would these work correctly when i only need +/- feeds to each gripper motor ? would i only need to use two of the 3 output cables/connections ?

thanks
murdo

Hi @Mac1 ,

You need a brushed ESC, not a brushless one!

Hello Willian,
sorry to bother you , I have looked all over Amazon and e-bay but i cannot find any brushed ESC 4S that will work between 12-16/18 V.
all i can find is either 2-3s or they are lower power rated than 12 V
any helpful links to source the correct brushed ESC

thanks appreciate

hello willian
is this the correct unit ?

Hi murdo,

How about this one?
DFRobot 40A Bidirectional Brushed ESC Speed Controller (XT60 Connector) - RobotShop

hello K.deboer
that one is only * Voltage range: 7V-24V (lithium battery 2S) not 4s

thanks for your help and trying ,
I think i may have found one , awaiting willian to confirm :slight_smile:

Thanks murdo,

I saw the 7-24V part. That explains why the very same controller failed for me a while back. I thought it was due to some other issue. That explains it! :stuck_out_tongue_winking_eye:

Hi

That is “single way”. you need one that is able to reverse to go in both directions.

This should actually work. a 4s battery can be charged up to 16.8v. The 2S in the description is likely a mistake, or maybe it was suposed to be “2S-6S”.

This is really confusingly marketed, but apparently (as per a comment on the dfrobot website)

so it should be suitable for 4S batteries.

Hello Eliot,
I this one not suitable ?

Single Way Brushed ESC Switch 6V-16V 2S-4S 20A (see above post from me )

Specifications:

  • Voltage: 6V-16V (2S-4S lithium battery)
  • Current: 20A
  • BEC: 5V max 1.5A
  • Remote control signal PWM: (1000-2000) (1100-1900) (the runs adapt automatically)
    Packing includes:
    1 x Brushed ESC (PC)

thanks
murdo

As @williangalvani mentioned,

A bidirectional one lets you open and close the gripper, but a single way one only lets you do one of those (open OR close). Same issue applies for the left/right rotation - you need a bidirectional ESC to be able to go both ways.

Hello willian.
would this one be correct ?

High Voltage 3S-6S 24V Dual Way Brushed ESC DIY Replacement Part for RC Boat

  • Durable 12-24v high pressure brushed two-way ESC
  • This ESC can be connected to 24v voltage
  • Help to solve the problem that the ESC cannot be connected to high voltage, let DIY get more fun
  • The current is up to 30A, can be connected to 775 895 motor, with heat sink to improve heat dissipation
  • The ESC receiver has a BEC 5V.

thanks appreciate your help

That specification sounds fine :slight_smile:

Hello Eliot & Willian,
I will order these

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