screeching halt

[tyhu]

Hi, how to understand robot "screeching halt"? I think system variable $CP_VEL_TYPE to avoid that. But why does screeching halt happen?

Thanks.

[kr16_2]

When does it happen?
If it happens during AUT or EXT then you drop Drives_OFF signal to FALSE (or switch modes during robot run)
Result is applying the brakes to running motors and cutting drives power off - VERY BAD from mechanical point of view and bad noise.
Same will happen during fast motion in T2 if you drop dead man.

[tyhu]

Thanks, Kr16_2.

No screeching halt happens in robots here. The reason to ask is that $CP_VEL_TYPE=#VAR_ALL is suggested to avoid screeching halt.  If $CP_VEL_TYPE=#Constant, the screeching halt can possibly happen. I just dont know why. Any physics or Kuka control can explain?

Have a nice day

[SkyeFire]

KRs have four different types of stop.  A "normal" stop, like hitting the Stop button (not the E-stop) on the KCP, lets the robot finish out the current motion block and stops gracefully.  A normal E-stop performs a fast path-maintaining braking maneuver -- the robot stops as quickly as it can using motor deceleration, and minimizing drift off path.  The robot actually stops under power and then engages the motor brakes.
A "screeching" stop should only happen for certain drastic conditions, like an Operator Safety fault, or someone switching the robot from Auto to Teach in mid-motion, or something drastic like a resolver failure.  For these types of drastic conditions, the robot simply kills power to the motors and slams the brakes on without any regard to damage or wear.  This should NOT happen on any regular basis.

The key question is WHEN are these "screeching stops" happening?  When someone hits an E-Stop?  If someone kills power?  Someone opens a safety gate while the robot is moving rapidly?   What error messages are coming up with these stops?

I don't see how $CP_VEL_TYPE is relevant, unless you have a bad program that is (for example) creating over-speed conditions on A4/A6 due to a wrist singularity.

[mookie]

KRs have four different types of stop.  A "normal" stop, like hitting the Stop button (not the E-stop) on the KCP, lets the robot finish out the current motion block and stops gracefully.  A normal E-stop performs a fast path-maintaining braking maneuver -- the robot stops as quickly as it can using motor deceleration, and minimizing drift off path.  The robot actually stops under power and then engages the motor brakes.
A "screeching" stop should only happen for certain drastic conditions, like an Operator Safety fault, or someone switching the robot from Auto to Teach in mid-motion, or something drastic like a resolver failure.  For these types of drastic conditions, the robot simply kills power to the motors and slams the brakes on without any regard to damage or wear.  This should NOT happen on any regular basis.

The key question is WHEN are these "screeching stops" happening?  When someone hits an E-Stop?  If someone kills power?  Someone opens a safety gate while the robot is moving rapidly?   What error messages are coming up with these stops?

I don't see how $CP_VEL_TYPE is relevant, unless you have a bad program that is (for example) creating over-speed conditions on A4/A6 due to a wrist singularity.

its clearly 1am and i am 600 miles from home.

I love you

but i felt the need to point out screeching halt to you..

remember when we were in france, and i walked in on you in the shower...

that is the clear definition of screeching halt...


just saying




we could go back to the sheep







baaaaaa

[tyhu]

haha. thanks, guys

[py_programmer]

Skyfire, you kill me with the suspense! What is the fourth kind?

[SkyeFire]

I'd have to look it up again to be sure.  Going from memory, the stops are something like this:

1.  Program stop.  Finish the current motion and stop program execution.  This is what you get by hitting the "stop" button on the KCP.
2.  Path-maintaining stop (normal E-stop).  The robot decelerates as hard as it can without falling off the motion path, using dynamic braking.  The motors shut down and the brakes come on as soon as the robot comes to a complete stop.
3.  Non-Path-maintaining.  The robot performs the maximum possible dynamic braking deceleration, paying minimal attention (or none at all) to staying on path.  The motors shut down and the brakes come on as soon as the robot comes to a complete stop.
4.  Short-circuit stop.  Only used in the event of a serious error or safety fault.  The motors are shut down and the brakes slammed on instantaneously with no regard to path, deceleration, or hardware damage.

I think there's a system setting to control whether an E-stop uses 2 or 3, but I can't swear to it.