About shifting based on the FRAME coordinate system

The easiest way is just by using SHIFT command (AS Language Manual).

SHIFT is referenced to XYZ of the current BASE coordinate.

So what a lot of people do is set the BASE to the user frame and therefore the SHIFT will always be relative to the user frame.

So any transformation taught can be shifted relative to the BASE (cannot be used with joint angles #):

- BASE user_frame

- LMOVE SHIFT(a BY X,Y,Z).

- POINT offset_a = SHIFT(a BY X,Y Z).

- LMOVE offset_a

You're welcome.

A word of caution though.

Swapping between different BASES in programs, all though completely normal, allowed, common and simply done, it can introduce problems when it comes to teaching positions relative to the BASE.

You need to make sure the correct BASE coordinate has been executed prior to teaching.

I refer to this as:

'Be in the right FRAME of mind when teaching or it could turn your world upside down'.

You can't view it by variable name if you're using a variable name as it only stores the transformation values relative to any variable name used.

BASE command in the terminal returns the current transformation values in use and allows to change it.

BASE command in a program, just executes it and applies the transformation values directly.

Aux Function 0506 on the teach pendant also returns the current transformation values in use.

BASE coordinates remain fixed at the last values used unless by manual or programmatical change, even in the event of a power cycle.

So this works well if you wish to programmatically track BASE values.

Not very common for this to be tracked if I'm honest, however if you do want to track BASE changes, or display what current base is selected, you could code into a PC Task to display status lamps on the IFP for BASE changes.

Very crude, but the below video clip shows something in action.

As a rule, I ***NEVER*** change the BASE of a robot. In my particular world, there are just too many problems that doing this could create. Especially if I change the BASE on an application and leave it for some other poor goombah to discover by accident. Most robot users/programmers do not understand transformations, so why leave these boobytraps out there for others to find?

It's been many years, so please forgive if my transformation math is not exactly correct.

If I remember correctly, SHIFT only applies to points in the BASE coordinate system.

So the problem statement is:

GIVEN:

• arbitrary FRAME (call it: frame1) out in robot space taught in the default BASE robot coordinate system
• an X-Y-Z pattern of points relative to frame1 (call them pt1 = frame1+TRANS(X1, Y1, Z1), pt2 = frame1+TRANS(X2, Y2, Z2), etc)

FIND: I desire to move the points pt1, pt2, etc. to my dimensional specification within frame1 (sort of like using SHIFT inside frame1)

SOLUTION:

• OPTION1: Use TRANS function to calculate transformations within the frame1 coordinate system
  • command: pt1_new = frame1+TRANS(X1+X1_shift, X2+X2_shift, etc)
• OPTION2: inverse the frame1 back to BASE and then use SHIFT within the BASE coordinate system
  • command: pt1_new = SHIFT(-frame1+pt1 BY X1, Y1, Z1)
    • ASSUMPTION: all of the various coordinate systems are aligned suitably. Else it may be necessary to change the order of the X, Y, Z components to get the desired changes

Like I said, it has been many years and my command might be incorrect. I'd have to find a machine and test this and prove the correct trans math order. But I hope that you are understanding my intention.