4.35d, Index ip, RTCP advice

[Chevvron]

Tom,

Thanks for last weeks answers but I now have a few more queries.

Does 4.35d pass a new pivot to chuck length within Kinematics.txt through to KMotion CNC in this without a rebuild or I have misunderstood the version change log ?

Our A and B rotary axis have single ended index pulses.
But 38 = A axis and bit 40 = B axis index.
For the A axis Ch5A and Ch5B diff -ve inputs are biased.
Ch5A and Ch5B diff +ve inputs are connected together, connected to the A axis encoder index pulse output.
The above appears to work but is this correct ?

Our 5 axis machine init X,Y,Z linear axis velocities =150mm/sec.
Our G0 velocity is 9000mm/min.
Our G1 cutting speed is 3000mm/min.
Our maximum A axis pivot to chuck length + tool length = 220mm.
What A and B axis rotary init velocities in deg/sec would you set to achieve optimum synchronised motion for all axes ?

I initially set the KMotion CNC velocities to thee same as the init values but I have then had to severely them to achieve stable 5 axis RTCP motion.
Can you please explain the relationship between the KFlop init and KMotion CNC values ?

Regards,
Tim

[TomKerekes]

Hi Tim,

Does 4.35d pass a new pivot to chuck length within Kinematics.txt through to KMotion CNC in this without a rebuild or I have misunderstood the version change log ?

Yes the CKinematics5AxisTableAGimbalB should do this now in Version 4.35d

Our A and B rotary axis have single ended index pulses.
But 38 = A axis and bit 40 = B axis index.
For the A axis Ch5A and Ch5B diff -ve inputs are biased.
Ch5A and Ch5B diff +ve inputs are connected together, connected to the A axis encoder index pulse output.
The above appears to work but is this correct ?

Sorry I don't understand what you are doing. I don't understand why you would connect A, B, and Index together.

Our 5 axis machine init X,Y,Z linear axis velocities =150mm/sec.
Our G0 velocity is 9000mm/min.
Our G1 cutting speed is 3000mm/min.
Our maximum A axis pivot to chuck length + tool length = 220mm.
What A and B axis rotary init velocities in deg/sec would you set to achieve optimum synchronised motion for all axes ?

The Trajectory planner should slow down so everything stays synchronized. But the rotational speed to move the tip at 150 mm/sec would be.

tip speed = radius x omega

omega = tip speed / radius = 150 mm/sec / 220 mm = 0.682 radians/sec

0.682 radians/sec x 180 degrees/Pi = 39 degrees /sec

[Chevvron]

Tom,
Thanks again for the prompt reply.
I will download 4.35d and try.
My rotary axis encoder input was confused but just clarify :

Encoder index+ to ch5A+, encoder index- to ch5A- maps to bit 38 on KFlop ?

My logic for rotary axis velocity was the same as your reply below but we do have a shorter pivot to tool tip than I stated.

KFlop / init X, Y, Z linear vel =150mm/sec and acc = 150mm/sec/sec, 4e+09 jerk.
AB (should be C) rotary axis vel = 36deg/sec and acc = 52deg/sec/sec, 4e+09 jerk.
KFlop plots look good with p=0.5, no i or d and vff = 0.01.
The linear axis are lead screw direct drive and the rotary axis are harmonic drive actuators.

KMotion CNC X,Y, Z linear vel = 6in/sec and acc = 12inc/sec/sec.
AB (should be C) rotary axis vel = 36deg/sec and acc = 52deg/sec/sec.
Kinematics.txt uses Kinematics5AxisGimbalAB.

KMotion CNC jogs RTCP okay but to run a program with stable motion I have had to reduce the velocity and acceleration dramatically in the trajectory planner screen otherwise the axes attempt to move very violently at some points in the program.

G0 moves cause violent motion resulting in the following error limit being exceeded.

I thought I understood that if Hardware Range = 0 then the axis vel and acc parameters would not be exceeded as the software trajectory planner had control.

What don't I understand or what am I missing ?

Regards,
Tim

[TomKerekes]

Hi Tim,

Encoder index+ to ch5A+, encoder index- to ch5A- maps to bit 38 on KFlop ?

correct

KMotion CNC X,Y, Z linear vel = 6in/sec and acc = 12inc/sec/sec.

Here the acceleration is set to double what it is in KFLOP. Was that intentional?

KMotion CNC jogs RTCP okay but to run a program with stable motion I have had to reduce the velocity and acceleration dramatically in the trajectory planner screen otherwise the axes attempt to move very violently at some points in the program.

which axis needs to be reduced?

G0 moves cause violent motion resulting in the following error limit being exceeded.

G0 moving which axis? How far?

A common problem is to set too high velocities but only test small moves that don't go fast and think high velocities are possible. Did you actually test on the Step Response Screen those speeds?

Also with Kinematics Rapids should be treated as Feeds in order to properly follow the proper path. See here.

[Chevvron]

Tom,
I have only just got to use the machine late this evening.
I was worried about your comment of not using high enough velocities to test the machine.
I have attached motion plots for your comments please.
Tim

[TomKerekes]

Hi Tim,

Those moves are just long enough to get up to maximum speed.

What is the resolution of your system in counts/inch or Counts/degree?

Note you can copy a single window vs the whole desktop with Alt-PrintScreen.

Plot Error to see the Following Error more clearly.

[Chevvron]

Tom,
The information below is from memory as I am now at home.
The input gain in the init file is scaled so that the resolution is 1 micron.
The linear axis feedback is the emulated quadrature output from the Stober direct drive lead screw drives.
The rotary angular axis drives are harmonic drive actuators scaled such that 2275 counts = 1 degree.
I will resend the motion plots as single screens tomorrow along with error plots.
I will also email our init file.
Regards,
Tim

[TomKerekes]

Hi Tim,

In that case it seems you are testing at the Trajectory Planner setting's Velocities and higher than the Trajectory Planner Accelerations so its not clear why you need to reduce the settings.

If you send me all your settings, init file, and a GCode fragment that fails I can try to see if I can figure it out.