Auto_Bed_Leveling: Z-Probe Repeatability code

[Roxy]

There may be a small issue with this code... Please post the Marlin_main.cpp file. If there is a problem, I'll edit it for you. But "Yes..." This is the code base you should be using now.

[revwarguy]

Was there any version of this adapted for a delta?

[revwarguy]

Hello Roxy,
Ive been lurker here and just wanted to say thanks for the huge amount of help you've offered here.

I am just trying to use my z probe for the first time, so I thought I would start out easy by trying the M48, but it doesn't work.

First, I have a delta with a probe that is placed by hand (which means it doesn't need to be engaged or retracted, so just for now, I've inserted a return at the top of those routines) and the switch trigggers when at 18.21mm above the zero location (as determined by the paper test - it prints fairly well at this point.)

When I execute a M48 v3 the probe is lowered to Z_RAISE_BEFORE_HOMING, but then it just stays there, printing out a report with all the same values. Debug statements Ive inserted show the run_z_probe() getting repeatedly called, but nothing moves.

The m119 appears to work fine - the probe (hooked into zmin) is OPEN normally, and TRIGGERED when the switch is closed.

Any ideas?

[Roxy]

The

static float probe_pt(float x, float y, float z_before, ProbeAction retract_action=ProbeEngageRetract, int verbose_level=1) {

function raises and lowers the probe. And it controls the engaging of the probe. Did you make modifications to it? Or are you just not calling it? Either way, why don't you post the code you changed so we can talk about it.

[Roxy]

Was there any version of this adapted for a delta?

This code should work just fine with a Delta printer. However, with that said, my suspicion is that Delta printers are more susceptible to repeatability problems caused by different types of movements. If we knew what types of movements exposed those repeatability issues in Delta printers it might make sense to add a Delta option to the M48 command so the printer could be stressed harder.

With that said... It should work just fine and you should get a number to help you understand how good or bad your mechanics are.

[revwarguy]

Thanks for the help.

I am pretty sure that I am not using the code you are referring to that uses probe_pt(), so I went to try and get it by clicking on the "M48.c" link that is on the first post in this thread, but all I get is a black screen with

http://3dprintboard.com/attachment.p...5&d=1398698586

Then, I saw in the previous few posts that you specify a link to the main Marlin code, which I pulled and it looks identical to the code I have - the M48 code never calls probe_pt() but run_z_probe().

Looking at run_z_probe(), it does (in summary) calls to:

prepare_move_raw();
st_synchronize();
endstops_hit_on_purpose();

enable_endstops(false);

calculate_delta(current_position);
plan_set_position(delta[X_AXIS], delta[Y_AXIS], delta[Z_AXIS], current_position[E_AXIS]);

float zPosition = -10;
plan_buffer_line(current_position[X_AXIS], current_position[Y_AXIS], zPosition, current_position[E_AXIS], feedrate/60, active_extruder);
st_synchronize();

// we have to let the planner know where we are right now as it is not where we said to go.
zPosition = st_get_position_mm(Z_AXIS);
plan_set_position(current_position[X_AXIS], current_position[Y_AXIS], zPosition, current_position[E_AXIS]);

// move up the retract distance
zPosition += home_retract_mm(Z_AXIS);
plan_buffer_line(current_position[X_AXIS], current_position[Y_AXIS], zPosition, current_position[E_AXIS], feedrate/60, active_extruder);
st_synchronize();

// move back down slowly to find bed
feedrate = homing_feedrate[Z_AXIS]/4;
zPosition -= home_retract_mm(Z_AXIS) * 2;
plan_buffer_line(current_position[X_AXIS], current_position[Y_AXIS], zPosition, current_position[E_AXIS], feedrate/60, active_extruder);
st_synchronize();

and then returns the Z position found.

So, it never makes a call to probe_pt(). However, this does not appear to be working in my config. It looks like it ought to work for a delta, but it always just returns without having moved the probe and returns the same Z position it started with. Kinda stuck.

Is odd that the probe_pt() routine is still in marlin_main.cpp, and it's called by the auto leveling command g29, but not g30, so I guess when M48 was "folded in" someone rewrote some of it? I kinda wanted to tackle g29 and g30 next, so I guess I need to figure out what's wrong with run_z_probe().

[Roxy]

Thanks for the help.

You are most welcome.

Is there anywhere else I can find the code that uses probe_pt() in the M48 implementtion?

Try this:

   case 48: // M48 Z-Probe repeatability
        {
            #if Z_MIN_PIN == -1
            #error "You must have a Z_MIN endstop in order to enable calculation of Z-Probe repeatability."
            #endif


	double sum=0.0; 
	double mean=0.0; 
	double sigma=0.0;
	double sample_set[50];
	int verbose_level=1, n=0, j, n_samples = 10, n_legs=0, engage_probe_for_each_reading=0 ;
	double X_current, Y_current, Z_current;
	double X_probe_location, Y_probe_location, Z_start_location, ext_position;
	
	if (code_seen('V') || code_seen('v')) {
        	verbose_level = code_value();
		if (verbose_level<0 || verbose_level>4 ) {
			SERIAL_PROTOCOLPGM("?Verbose Level not plausable.\n");
			goto Sigma_Exit;
		}
	}


	if (verbose_level > 0)   
		SERIAL_PROTOCOLPGM("M48 Z-Probe Repeatability test.   Version 1.85\n");


	if (code_seen('n')) {
        	n_samples = code_value();
		if (n_samples<4 || n_samples>50 ) {
			SERIAL_PROTOCOLPGM("?Specified sample size not plausable.\n");
			goto Sigma_Exit;
		}
	}


	X_current = X_probe_location = st_get_position_mm(X_AXIS);
	Y_current = Y_probe_location = st_get_position_mm(Y_AXIS);
	Z_current = st_get_position_mm(Z_AXIS);
	Z_start_location = st_get_position_mm(Z_AXIS) + Z_RAISE_BEFORE_PROBING;
	ext_position	 = st_get_position_mm(E_AXIS);


	if (code_seen('E') || code_seen('e') ) 
		engage_probe_for_each_reading++;


	if (code_seen('X') || code_seen('x') ) {
        	X_probe_location = code_value() -  X_PROBE_OFFSET_FROM_EXTRUDER;
		if (X_probe_location<X_MIN_POS || X_probe_location>X_MAX_POS ) {
			SERIAL_PROTOCOLPGM("?Specified X position out of range.\n");
			goto Sigma_Exit;
		}
	}


	if (code_seen('Y') || code_seen('y') ) {
        	Y_probe_location = code_value() -  Y_PROBE_OFFSET_FROM_EXTRUDER;
		if (Y_probe_location<Y_MIN_POS || Y_probe_location>Y_MAX_POS ) {
			SERIAL_PROTOCOLPGM("?Specified Y position out of range.\n");
			goto Sigma_Exit;
		}
	}


	if (code_seen('L') || code_seen('l') ) {
        	n_legs = code_value();
		if ( n_legs==1 ) 
			n_legs = 2;
		if ( n_legs<0 || n_legs>15 ) {
			SERIAL_PROTOCOLPGM("?Specified number of legs in movement not plausable.\n");
			goto Sigma_Exit;
		}
	}


//
// Do all the preliminary setup work.   First raise the probe.
//


        st_synchronize();
        plan_bed_level_matrix.set_to_identity();
	plan_buffer_line( X_current, Y_current, Z_start_location,
			ext_position,
    			homing_feedrate[Z_AXIS]/60,
			active_extruder);
        st_synchronize();


//
// Now get everything to the specified probe point So we can safely do a probe to
// get us close to the bed.  If the Z-Axis is far from the bed, we don't want to 
// use that as a starting point for each probe.
//
	if (verbose_level > 2) 
		SERIAL_PROTOCOL("Positioning probe for the test.\n");


	plan_buffer_line( X_probe_location, Y_probe_location, Z_start_location,
			ext_position,
    			homing_feedrate[X_AXIS]/60,
			active_extruder);
        st_synchronize();


	current_position[X_AXIS] = X_current = st_get_position_mm(X_AXIS);
	current_position[Y_AXIS] = Y_current = st_get_position_mm(Y_AXIS);
	current_position[Z_AXIS] = Z_current = st_get_position_mm(Z_AXIS);
	current_position[E_AXIS] = ext_position = st_get_position_mm(E_AXIS);


// 
// OK, do the inital probe to get us close to the bed.
// Then retrace the right amount and use that in subsequent probes
//


        engage_z_probe();	


	setup_for_endstop_move();
	run_z_probe();


	current_position[Z_AXIS] = Z_current = st_get_position_mm(Z_AXIS);
	Z_start_location = st_get_position_mm(Z_AXIS) + Z_RAISE_BEFORE_PROBING;


	plan_buffer_line( X_probe_location, Y_probe_location, Z_start_location,
			ext_position,
    			homing_feedrate[X_AXIS]/60,
			active_extruder);
        st_synchronize();
	current_position[Z_AXIS] = Z_current = st_get_position_mm(Z_AXIS);


	if (engage_probe_for_each_reading)
        	retract_z_probe();


        for( n=0; n<n_samples; n++) {


		do_blocking_move_to( X_probe_location, Y_probe_location, Z_start_location); // Make sure we are at the probe location


		if ( n_legs)  {
		double radius=0.0, theta=0.0, x_sweep, y_sweep;
		int rotational_direction, l;


			rotational_direction = (unsigned long) millis() & 0x0001;			// clockwise or counter clockwise
			radius = (unsigned long) millis() % (long) (X_MAX_LENGTH/4); 			// limit how far out to go 
			theta = (float) ((unsigned long) millis() % (long) 360) / (360./(2*3.1415926));	// turn into radians


//SERIAL_ECHOPAIR("starting radius: ",radius);
//SERIAL_ECHOPAIR("   theta: ",theta);
//SERIAL_ECHOPAIR("   direction: ",rotational_direction);
//SERIAL_PROTOCOLLNPGM("");


			for( l=0; l<n_legs-1; l++) {
				if (rotational_direction==1)
					theta += (float) ((unsigned long) millis() % (long) 20) / (360.0/(2*3.1415926)); // turn into radians
				else
					theta -= (float) ((unsigned long) millis() % (long) 20) / (360.0/(2*3.1415926)); // turn into radians


				radius += (float) ( ((long) ((unsigned long) millis() % (long) 10)) - 5);
				if ( radius<0.0 )
					radius = -radius;


				X_current = X_probe_location + cos(theta) * radius;
				Y_current = Y_probe_location + sin(theta) * radius;


				if ( X_current<X_MIN_POS)		// Make sure our X & Y are sane
					 X_current = X_MIN_POS;
				if ( X_current>X_MAX_POS)
					 X_current = X_MAX_POS;


				if ( Y_current<Y_MIN_POS)		// Make sure our X & Y are sane
					 Y_current = Y_MIN_POS;
				if ( Y_current>Y_MAX_POS)
					 Y_current = Y_MAX_POS;


				if (verbose_level>3 ) {
					SERIAL_ECHOPAIR("x: ", X_current);
					SERIAL_ECHOPAIR("y: ", Y_current);
					SERIAL_PROTOCOLLNPGM("");
				}


				do_blocking_move_to( X_current, Y_current, Z_current );
			}
			do_blocking_move_to( X_probe_location, Y_probe_location, Z_start_location); // Go back to the probe location
		}


		if (engage_probe_for_each_reading)  {
        		engage_z_probe();	
          		delay(1000);
		}


		setup_for_endstop_move();
                run_z_probe();


		sample_set[n] = current_position[Z_AXIS];


//
// Get the current mean for the data points we have so far
//
		sum=0.0; 
		for( j=0; j<=n; j++) {
			sum = sum + sample_set[j];
		}
		mean = sum / (double (n+1));
//
// Now, use that mean to calculate the standard deviation for the
// data points we have so far
//


		sum=0.0; 
		for( j=0; j<=n; j++) {
			sum = sum + (sample_set[j]-mean) * (sample_set[j]-mean);
		}
		sigma = sqrt( sum / (double (n+1)) );


		if (verbose_level > 1) {
			SERIAL_PROTOCOL(n+1);
			SERIAL_PROTOCOL(" of ");
			SERIAL_PROTOCOL(n_samples);
			SERIAL_PROTOCOLPGM("   z: ");
			SERIAL_PROTOCOL_F(current_position[Z_AXIS], 6);
		}


		if (verbose_level > 2) {
			SERIAL_PROTOCOL(" mean: ");
			SERIAL_PROTOCOL_F(mean,6);


			SERIAL_PROTOCOL("   sigma: ");
			SERIAL_PROTOCOL_F(sigma,6);
		}


		if (verbose_level > 0) 
			SERIAL_PROTOCOLPGM("\n");


		plan_buffer_line( X_probe_location, Y_probe_location, Z_start_location, 
				  current_position[E_AXIS], homing_feedrate[Z_AXIS]/60, active_extruder);
        	st_synchronize();


		if (engage_probe_for_each_reading)  {
        		retract_z_probe();	
          		delay(1000);
		}
	}


        retract_z_probe();
	delay(1000);


        clean_up_after_endstop_move();


//      enable_endstops(true);


	if (verbose_level > 0) {
		SERIAL_PROTOCOLPGM("Mean: ");
		SERIAL_PROTOCOL_F(mean, 6);
		SERIAL_PROTOCOLPGM("\n");
	}


SERIAL_PROTOCOLPGM("Standard Deviation: ");
SERIAL_PROTOCOL_F(sigma, 6);
SERIAL_PROTOCOLPGM("\n\n");


Sigma_Exit:
        break;
	}
#endif		// ENABLE_AUTO_BED_LEVELING

[revwarguy]

Ok, I substituted the code you provided in the last post with the commented out code for all of M48. It compiled and ran (I just issued an M48 with no arguments right after a G28), but it immediately tries to go off the printer radius without descending (the front two of the three delta steppers move, but not the rear one - for a delta to descend, all three motors must move together.) In the monitor log, it printed
"M48 Z-Probe Repeatablility test Version 1.85
Starting Probe: 434.0500, Ending Probe"

I will have to look at the code closer to see if there is a translation somewhere in it or what it calls to do the transform of regular cartesian to delta coordinates, but that 434.05 number looks wrong to me. Right after a G28, the nozzle on my machine is about 192mm above the bed (Z = 192), so I'll have to look to see where the 434 number is coming from.

G28 and M119 all look good, and I can print perfectly with the machine all day long.

Perhaps I a bit confused as to the input arguments. Here are what I believe to be the relavant setting in Configuration.h:

#define X_PROBE_OFFSET_FROM_EXTRUDER 0
#define Y_PROBE_OFFSET_FROM_EXTRUDER -19
#define Z_PROBE_OFFSET_FROM_EXTRUDER 23 //-18.48 // Increase this if the first layer is too thin (remember: it's a negative number so increase means closer to zero).

#define Z_RAISE_BEFORE_HOMING 20.0 // (in mm) Raise Z before homing (G28) for Probe Clearance.
// Be sure you have this distance over your Z_MAX_POS in case
#define XY_TRAVEL_SPEED 1000 // X and Y axis travel speed between probes, in mm/min
#define Z_RAISE_BEFORE_PROBING 7.0 //How much the extruder will be raised before traveling to the first probing point.

#define Z_RAISE_BETWEEN_PROBINGS 7.0 //How much the extruder will be raised when traveling from between next probing points

Some of these might be for G29 or G30 as well.

About my probe - its just a snap on microswitch that has the switch arm contact point directly in front of the nozzle (x offset = 0) and a bit to the right (y offset = 19mm) and the switch arm hangs down a bit. I've measured that the switch toggles right at a height of 18.48mm above the position when the nozzle itself is at zero. However, there is about 5mm of distance between where the switch arm just contacts the surface and the switch triggers, so I made the height offset to be 23. (I saw in the code where it should try to go Z-10mm during the probe.)

Are these settings correct?

The comment in the code, "// Be sure you have this distance over your Z_MAX_POS in case" is rather vague and poor english so I am not really sure what is meant by it.

[Roxy]

What code base are you using? Can you pull down the Beckdac code and move your settings to that? I know what is in that fork and how things are setup in there. If you move your setting over to that code base it will be much easier to help you get things going.

Beckdac's code is at: https://github.com/beckdac/Marlin

[Roxy]

Oh? I didn't expect that. OK... How about we use this repository:

https://github.com/ErikZalm/Marlin

What I'm trying to do is not use the recent code at: https://github.com/MarlinFirmware/Marlin They have made change after change without testing anything and right now the Auto Bed Leveling is sick. So let's try that ErikZalm link and get your stuff going using that.