Affordable gripper / grabber / manipulator

manipulators-tools

#1

I’m working on a grabber experiment

It’s the grabber of Makeblock (the two finger version). I disassembled the motor from the claw to build that into a PVC tube with an axis from ships RC model.

The motor has a two wire connection, that needs to be connected to the Arduino.
As I read there are still 5V connections free on the Arduino.
Being not yet an arduino expert, I wonder if the Arduino has space left for a 5V operations connection and if the cockpit software has two buttons left (open/close) so that I can controll the grabber from the Laptop.

Costs so far in USD
Gripper 29,-
Ships axis 15,-
PVC tupe 16,-
Small stuff 25,-

Total 85,-


#2


#3

Here we see the disassembled Grabber of Makeblock. And the mounting of the motor in the PVC cap that will be mounted on the watertight PVC tube.
I working on this grabber for the coming days and will post pictures of the process everyday.


#4

Here’s a pic of the grabber mounted on the screwable end of the PVC tube


#5

Her we see the ship’s axis, with coupler and the grabber, ready to be assembled.
It appears that the shaft of the axis needs to be shortened and I hope this will not affect the watertight abilities. To be sure I will add extra grease in the axis.


#6

Shortening the outer tube of the axis and mounting it in the close cap of the tube with grabber.


#7

Flex coupler mounted on axis

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#8

Axis mounted in coupler


#9

Outer axis mounted in place, watertight


#10

Outer axis leading to grabber


#11

Overview before mounting


#12

Assembled and still accessable by unscrewing the close cap
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#13

The grabber, socket and tube


#14

Looks great! After watching your build, I bought a few of the earlier designed grippers with the four fingers.

As for control, you have a brushed motor. See if you can find a cheap brushed ESC and connect it to channel D11, where the camera servo usually is.


#15

Hi Kevin,

thanks man. I saw them too but I choose first the two finger version.
As for the connection to the Arduino I do need some help. So D11 should be the control with 5V in it.

thanks


#16

No, you won’t be able to do 5V over D11, but it will give you a PWM channel with forward/reverse. You will need to use an ESC with the servo connector connected to D11. You will need an outside 5V power source to power that ESC and that’s where it gets messy.

As a trial, I removed my camera servo channel (D11) and plugged in one of my thruster channels. Here is what you will get if you run a motor with ESC combo off D11:

  1. Because you are sending a constant PWM signal, when you press a button for forward/reverse it is going to maintain whatever forward/reverse power level you initiated until you center it again (“A” on the keyboard or “B” on the gamepad) or until you reverse the command.
  2. You can increase the power level by clicking the forward/reverse button more.

I recommend you try experimenting with your motor and ESC combo free of the grabber until you get the feel down. Be careful be cause you don’t have any limit switches.

I think I might try an M-100 motor with an external ESC with mine so I don’t have to worry about waterproofing like you do, but you have a great idea!


#17

Thanks! I’m not good at the Arduino, this actually my first experience, so I bought sepratly an Arduino to experiment with. So I can make a trial setup before I touch the Arduino in the OpenROV.:-))

Your idea makes it better, indeed no worries about waterproofing. This is maybe even more better because I was worrying about the effect on the buoyancy of the tube filled with air. I will effect the behavior of the OpenROV.

So I think I might follow along with you and replace the motor too and thus create an open structure and have less buoyency influance. Now I need to do some thinking about a new end version, but it will be an improvement.

An M-100 motor with an external ESC… I have to find out more about working with those.
I have to admit this will be the first time.


Payload Interface: Mechanical (Trident Kickstarter Update #10)
#18

Seems like this is the last discussion on the topic of Affordable gripper/grabber/manipulator back in March 23. 2015.
Assuming this tool was intended for OpenROV 2.6 2,7 and 2.8. I’m searching to see if there are anybody in our community that has found or developed any gripper/grabber/manipulator suitable for the Trident. Thanks in advance.


#19

Kaare, I had not seen this thread until tonight but this is very close to what I was brainstorming. I had not thought of using an ESC motor but that solves the whole waterproofing issue which I anticipated would be the weakest point. Waterproofing the bearing where the shaft exited the watertight compartment for the motor and the power supply. I was thinking about this for a Trident unit; putting the power supply, wifi and Arduino in the waterproof compartment with the motor, but now with the motor external, all that would have to penetrate would be wires to the motor.


#20

Hi Jim
Will you have a sketch and a Bill og Materials for your grabber/maniplator for the Trident?

Kaare