I've got a problem to solve!

RE: I've got a problem to solve!

beacon_dave — Thu, 07 Sep 2017 19:37:23 GMT

How about a time-of-flight type sensor placed on a stake behind the stump. Stick a disposable surveyor's target reflector on the stump. The Arduino can then measure the amount of deflection and if it exceeds a preset limit it triggers the alarm.

Could do something similar with a Pixy camera placed to the side of the tree and look at differences in successive images to detect how much the target has moved by.

RE: I've got a problem to solve!

dougw — Thu, 07 Sep 2017 19:10:16 GMT

I would suggest something simple like a deadman switch. A separate line from the tailhold to an independent anchor that opens or closes an alarm circuit when the tailhold moves enough to pull on the deadman line.

RE: I've got a problem to solve!

ntewinkel — Thu, 07 Sep 2017 18:32:38 GMT

Hi Clinton,

I would assume that during regular use there would be a fair bit of vibration, so it would be hard to detect "bad" movement amongst the regular movement.

The big question is at what point is it too late? What are the pre-failure warning signs we can use to determine when to sound the alarm?

Can a tilt sensor be used on the stump so that if it starts leaning over too far it sounds the alarm? Or is that already too late? - ie, by the time it tilts any amount the stump is already flying out of the ground?

Interesting question [View:/resized-image/__size/16x16/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-6f6cca2f-1785-48f5-ab06-1c8cae757f55/contentimage_5F00_1.png:16:16]

Cheers,

-Nico

RE: I've got a problem to solve!

DAB — Thu, 07 Sep 2017 17:57:44 GMT

Hi Clinton,

I would look at adding a strain gage to the cables.

The Arduino could monitor the cable stress and could quickly detect if there was a slackening in the cable due to stump movement.

It would be fairly easy to mount the strain gages with just some superglue and the Arduino could flash lights and turn on a buzzer when the strain measurements indicated a potential failure.

DAB

RE: I've got a problem to solve!

jw0752 — Thu, 07 Sep 2017 04:20:02 GMT

Hi Clinton,

If the stump is pulled out slowly the acceleration may be too low to sense. Also once the stump is moving it would have no acceleration. Finally if a root snaps the acceleration would certainly be detectable but it would be too late. How about securing your module on a stump and have a reel of string around a 10 turn pot. Tie the string off to another tree or just anchor it to the ground with a stake. If the tree starts to move it will pull string off the reel which will rotate the potentiometer. The Arduino can read the change in resistance and convert it to centimeters. Have this data transmitted back to the grapple yarder so that the movement can be assessed.

John