Feed rate very slow in 5 axis simultaneous

[AmitKumar171]

Dear Tom,

I am running a 5 axis g code in kflop board that is as follows.
N167 X0.4973 Y-5.5641 Z76.0197 A20.4252 C-148.8885 F2000
N168 X0.5097 Y-5.5923 Z76.0158 A20.0944 C-147.4391
N169 X0.5221 Y-5.6206 Z76.0118 A19.7754 C-145.9421
N170 X0.5345 Y-5.6489 Z76.0079 A19.4689 C-144.3973
N171 X0.5469 Y-5.6771 Z76.0039 A19.1756 C-142.8046
N172 X0.5593 Y-5.7054 Z75.9999 A18.8962 C-141.1644
N173 X0.5718 Y-5.7337 Z75.996 A18.6316 C-139.4773

But that g code is running at a feed of 20-40mmpm but i defined as F2000. So i want to get feed rate of F2000 for linear+angular move , so what changes i require for that in Kmotion init file and trajectory planner.

I tried using Inverse time feed rate also G93, that is also same (Feed rate of 20-40mmpm).

I have defined x, y, z as linear and a, c as rotary axis for the setup.

Waiting for your kind reply.

[TomKerekes]

Please post your Trajectory Planner Settings

[AmitKumar171]

Hi tom,

here are the trajectory planner settings.

trajectory planner

Waiting for your kind reply.

[TomKerekes]

Hi Amit,

The issue is that the XYZ motion is very small (0.18mm) and the angular motions are quite large (C moves 9 degrees).

C axis Acceleration limit is set at 80 degrees/sec^2.

So the fastest possible motion is using maximum C Acceleration to move 4.5 degrees, and maximum C Deceleration to stop over 4.5 degrees.

The formula:

Distance = 1/2 Acceleration x Time^2

can be used to calculate the time required to accelerate (0.335 seconds) and decelerate (0.335 seconds) the C axis. Total Motion Time = 0.67 seconds.

Obviously moving XYZ 0.18mm over 0.67 seconds is not 2000mm/min. Rather it ramps to ~30mm/min then back to a stop to remain in sync with the angular axes.


Or looking at it another way: to move XYZ 0.18mm at 2000mm/min would only take:

Time = Distance/Velocity = 0.18mm / 2000mm/min x 60sec/min = 5 milliseconds.

Imagine your C Table attempting to rotating 9 degrees in only 5 milliseconds!


KMotion's Trajectory Planner goes through great effort to move in the optimal manner, while honoring all the constraints of your machine.

HTH

[AmitKumar171]

Hi tom,

What is the solution of this problem , or how can we use inverse time G93 for our KmotionCNC trajectory planner.

How to do trajectory planner settings ?

How to resolve my problem of slow motion of axes. ?

Is putting Radius =1 in trajectory planner makes all axes smoother ?

Waiting for your kind reply.

[TomKerekes]

Hi Amit,

You must obey the laws of physics. If the GCode commands the C Axis to move 9 degrees, then the GCode must take the time it takes your C Axis to move 9 degrees.

The only options are:

#1 change the GCode to move the Trunnion Tables less
#2 change the machine to be able to move the Trunnion Tables faster

You can change the Trajectory Planner Accelerations and Velocities to huge values but if your machine is not capable of this then there will be huge errors and motor stalls.

[AmitKumar171]

Hi tom ,
if i do below solution what will happen in my motion of 5 axis.

Is putting Radius =1 in trajectory planner makes all axes smoother ?

Waiting for your kind reply.

[TomKerekes]

Hi Amit,

I don't think setting a radius would be appropriate for you. That method is for systems that operate on a cylinder of relatively constant radius such as this:





With Radius = 0 only XYZ are used to determine the desired Feedrate (if the Feedrate is achievable)

With Radius > 0 the radius is used to transform angular motion to linear motion (angle in radians x Radius) and assumed to be orthogonal to any XYZ motion. This can be useful so a simply specified Feedrate can achieve an approximate cutting rate even when angular axes are used or combined with linear motions.

In your case it wouldn't be appropriate or help as the motion is limited by what your C axis can do. Whenever the desired Feedrate is higher than what some axis can do that axis will limit the rate.

HTH

[AmitKumar171]

Hi tom,

Please help on how to implement G93 feedrate for this controller.

and how it should work,

Should i do motor tuning again for this feed rate issues ?

And in Step response screen, how should i do motor tuning for Rotary axis with counts/deg in trajectory planner.

I started doing same as step response for linear axis but, rotary axis is going extremely fast.

How step response works in case of Rotational axis in Trajectory planner.

Waiting for your kind reply.

[TomKerekes]

Hi Amit,

You don't respond to my previous posts so it is hard to tell what you understand.

Please help on how to implement G93 feedrate for this controller.

and how it should work

it works an most others. Here is a reference. What don't you understand?

Again if you use G94 or G93 to make a motion in 5 milliseconds that your machine can only move in 1 second, then the motion will still take 1 second regardless.

Should i do motor tuning again for this feed rate issues ?

Are your Velocities and Accelerations for your axes set properly? For your C Axis you have a maximum velocity of 83.33333 deg/sec and an acceleration of 80 deg/sec2. This means the axis takes over 1 second to accelerate to full speed. That seems a little slow. Have you tested higher acceleration? Does it work with small following errors? You might read this.

And in Step response screen, how should i do motor tuning for Rotary axis with counts/deg in trajectory planner.

To convert counts to degrees divide by the counts/degree for the axis in exactly the same way as with a linear axis where you convert from counts to mm by dividing by the counts/mm for the axis.

I started doing same as step response for linear axis but, rotary axis is going extremely fast.

Then move slower.

How step response works in case of Rotational axis in Trajectory planner.

Exactly the same as with a linear axis.