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Newton Gripper grip stregnth and failsafe

asked these questions two years ago on the YT gripper vid. I guess this is a better place to ask,

  1. What is the ultimate crush force and is it adjustable? You can assume I’d replace the plastic jaws with aluminum. Lite grip force so as to ‘not hurt anybody’ seems lame. This isn’t a toy -make it useful.
  2. Note on the failsafe below (on YT vid) : make it an option that can be disabled. I can see a need to grab something and hang on even though the battery has depleted.
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In my limited experience I think that it has good grip strength. I don’t think there’s a way for the user to adjust the grip. I assume you mean the official Newton product video since you didn’t include a link to any videos.

I agree that it should be user settable. To be fair, I have seen people on this forum talking about how they use the Newton Gripper for body recoveries in SAR missions, so not damaging the human body is a valid consideration. There’s also the obvious situation of curious people and careless operators that need to be accounted for. I have even been tempted to test it on myself a couple times though I’m not stupid enough to actually try it. It effortlessly slices through aluminum cans (even the top and bottom where it’s strongest) so I wouldn’t call it a toy.

I have never heard of this failsafe. I will try to test it and see if it exists. I leave my gripers closed when its not used and they have never moved. I also don’t understand how that failsafe would work. How is the gripper motor going to run when the battery is dead?

I have a few videos of testing it for fun.
Here I pick up a steel plate about as long as the ROV is wide:

Grabbing a bottle and some cans

You did actually look at the product page, right?

Grip Force (at tip) 97N 22lbf
Grip Force (in middle) 124N 28lbf
Push-rod Axial Load Rating 3 kg 6.6 lb
Minimum Linear Piston Travel 13.5 mm 0.53 in
Jaw Opening 62 mm 2.44 in
Time to Open/Close 1.6 secs

Hi @salvor1,

As @btrue mentioned, the gripping force and other information can be found in the Technical Details on the product page. The gripper is designed to be open/close while a PWM signal commands it to, so there’s no direct control over the torque. It has torque limits built in, which are defined as proportions of the motor stall current.

The gripper’s firmware is open source, so you’re welcome to modify those limits in your own device, although understandably if you increase them and end up causing the motor to burn out that’s not something we can cover under warrantee.

If you wanted to you could even write a custom firmware that uses the PWM input to specify the motor torque to limit at, instead of when to open/close from the current position. That could then be controlled by PWM increment/decrement commands, instead of the current “momentary” approach which commands continuous opening/closing while a joystick button is pressed.

The initial response to that youtube comment is still the case now:

If we do at some point implement an “open on power loss” failsafe, it may only be “configurable” by uploading new firmware that has it enabled or disabled. It’s technically possible to implement some kind of configuration protocol on the signal pin that would allow changing something like that with just a sequence of PWM values held for a set period of time, but that can get complicated quite quickly, and may not be worth the extra complexity.