Posts by D_Oster

A couple of other options are to add the Ethernet I/P functionality to your robot controller, or to get a PLC that has a Device Net scanner. Getting keystrings modified by ABB takes a few weeks currently, and there may be a field bus adaptor required. Device Net is very straight forward and easy to set up in the robot.

As stated, the issue is the drive units that are in your robot - "Drive system 04".

These are obsolete, so getting an additional drive unit is going to be expensive to buy, and will have to come from a 3rd party, not ABB. So the cost of the drive unit, and then adding a keystring to enable the external axis functions, and the motor / cables etc is not cost effective.

VFD with a motor and some analog inputs/outputs would work nicely for what you are looking to do.

Coordinated axis are cool, but mostly not needed in most applications.

Have fun!

I'd suggest starting with checking that the gear ratio is 100% correct.

If you command the axis to move 360 degrees, is it spot on?

Here is the 6400S manual..

Sounds like you have a calibration offset issue or a load issue to me.

Does the robot have Load ID as an option? If not, do you have an IRC-5 that has the same tool and parts that you can run Load ID with and transfer the resulting update to your TCP?

I'd try to update the TCP using Load ID if possible first.

Then update your tool with the part in it as a payload.

Regarding the Cal Pend:

It does take the base into consideration when run, so any rotation about either the X or Y axis is part of the calibration process.

IF the robot has ABS-ACC, and any motor was changed, the ABS-ACC calibration is no longer valid, so it would have to be done again.

Not only does ABS-ACC compensate for gravity, it also takes friction into account.

Work arounds:

If ABS-ACC is on right now, turn it off, reteach your TCP, and see if your results are better.

As you most likely know, with a large robot like a 6600, and a very heavy payload gravity is going to have an impact on your repeatability in your "long reach" positions, so try to keep those critical points close in.

When you teach your TCP, I assume you are keeping your orientations very close to what you have done on the prior attempts.. Switch it up to see if this has an impact on how your tool behaves.. I have seen this on lots of 4400s, so you can sometimes move your error to another plane to make it more tolerable to the process.

Buy a nice digital level, and calibrate it off of the base of the robot for 0 degrees.. Take the T45(?) bolt and rubber pad off, wipe the grease spooge off, and set your level there.

Run the robot to the calibration position, and put your level on axis 5 using a square.

How close is it? Way off, you could try and tweak it in until you can get ABB on-site to use Cal-Pend, or ABS-ACC on it.

Try doing some friction compensation to get rid of the issue.. User's Guide, Topic: Manipulator

7.14 Defining friction compensation

Friction compensation can be activated to reduce path errors caused by friction and

backlash at low speeds (10 - 200 mm/s).

The friction model is a constant level with a sign opposite to the axis speed direction.

Friction ffw level (Nm) is the absolute friction level at (low) speeds greater than Friction

ffw ramp (rad/s) see Figure 29.

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The instruction TuneServo can be used to tune optimal values for each robot axis.

Note The system has to be loaded in service mode in order to be able to change these

parameters. See the Product Manual - Installation and Commissioning

Tuning procedure

The most straight forward way to tune the friction parameters is to consider one axis at

a time. Choose a motion which has a characteristic friction “bump” due to a specific

axis changing direction. Turn the friction compensation on for this specific axis and use

the default setting for friction level and ramp. Use the TuneServo command to gradually

increase the friction level until the bump in the path is removed.

Repeat this procedure for all axes.

• Choose Topics: Manipulator.

• Choose Types: Control parameters (Friction comp for IRB6600,6650 and 7600).

• Select the desired axis and press Enter .

• Select the desired parameter and change its value.

• Press OK to confirm the change.

Parameter Description

Friction ffw on Activates/deactivates friction compensation.

Friction ffw level Low speed motor friction level [Nm].

Friction ffw ramp Friction ramp [rad/s].

I hope that something useful comes of this..

Good luck, and don't eat too many carrots!