Skycam attempt, issues with planar movements

[skylarthegrey]

Hello,
Having an issue where XY plane movements are actually severely bowl shaped with the bottom deepest point at X0 Y0 (Im assuming that home is intended to be centered between the four anchors as the default limits were something like (500,500,150)-(-500,-500,0). Having gotten the pulley pitch correct this time at 62.8 (20mm diameter spool), and assuming that since M101 Qxxx and M102 is removed in the latest firmware compared to the old skycam fork this means the anchors are interpreted to be at the four top bounds of the axis limits? I think the below code from “robot_skycam.h” is what I need, but I’m not sure what SKYCAM_MOTOR_SIZE is (pulley diameter again?) or SKYCAM_PLOTTER_SIZE is (compensation for non point connection of all lines at EE?) or what units they are.

#define SKYCAM_MOTOR_SIZE   (4.5f)
#define SKYCAM_PLOTTER_SIZE (6.0f)
#define SKYCAM_COMPENSATION (SKYCAM_PLOTTER_SIZE/2.0f + SKYCAM_MOTOR_SIZE)

[Dan]

Your assumption about home position is correct.

Plotter size is the diameter of the tool head at the bottom of the four cables. you may find setting this number to zero gets better results, it all depends on the design of your tool head.

motor size is how far the motor projects inside the corner of the box. the machine size (ideal box) is not the same as the corner where the belt/cable last touches the motor and goes down in a straight line to the tool head.

i’ll add some comments to the code to clear this up for future users. Thanks!

Share pics/vid on our discord, we want to see what you’re making!

[Dan]

comments added to source code file robot_skycam.h

[skylarthegrey]

Hi Dan, Thanks for the updated comments!

One further clarification, it seems to follow that ((a-h)/2,(a-i)/2,a-c)-(-(a-h)/2,-(a-i)/2,0) therefore define the limits for M101? Would in that case
#define SKYCAM_MOTOR_SIZE (0.0f)
and setting limits to the measured anchor bounds rather than frame bounds be equivalent? Just trying to check I understand the parameter intent (basically to shrink the XY limit space).

//    i---------------j
//   /               /|
//  /               / |
// a--b         g--h  |
// |   \       /   |  |
// |    \     /    |  |
// |     \   /     |  k
// |      fff      | /
// |               |/
// c-------d-------e

Edit: hopefully code tags fix the image

• This reply was modified 3 years, 8 months ago by skylarthegrey.

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