Radio Controlled LT40 Project

[Ga Mtn Man]

I first started thinking about this project back in August of 2014 after seeing Dave Shepard's "Ghost-Mizer" video and pineywood's thread on his wireless mill.  While being up-close-and-personal with the cut does have its advantages, being trapped in a cloud of pink dust in the heat of a Georgia summer with the wind blowing the wrong way loses its appeal after a few hours, so I was determined to find a way out of the cloud.  Trading up to an LT40 with remote operator console was my first choice but the wallet said no.  A radio controlled mill that lets the sawyer move freely around the mill seemed like an ideal solution and might be more affordable.

Dave Shepard's video:
https://youtu.be/wacDqjavGZA

  A call to WM Indy shut down any thoughts of that...it's for all practical purposes a factory-only option and not cheap at that.  But as it happens, I  had an old late-80's vintage 5-channel Futaba Gold Series radio system packed away in the basement from when I used to fly RC (radio control) model airplanes.



 


Hmmm...add a few servos, some micro-switches and handful of relays...how hard could it be? : 

The radio uses an old narrow-band FM frequency which is no longer legal but with a little on-line research, I discovered that the transmitter RF (radio frequency) module could be replaced with the latest and greatest technology: 2.4Ghz, Frequency-Hopping, Spread-Spectrum, w/Telemetry and RSSI (relative signal strength indicator).  The RF module and matching Rx (receiver) only cost about $50.  This is the same radio control technology that most of the drones you see on TV use and also what the WM wireless unit uses.  This technology has some distinct advantages over the older radio systems, not the least of which is high immunity to interference, a very desirable thing when controlling an aircraft (or a sawmill).  I ordered the 2.4Ghz RF module and Rx and, realizing I was going to need more than 5 channels to control all of the mill functions, I found a 7-channel version of my Tx(transmitter) on e-bay for $30 and ordered that too.  Here's a pic of the stripped-down transmitter board with the new RF module installed:



 

The new RF module is the small "piggy-back" board in the upper center of the main board with the yellow wire connected to the bottom.  The light colored board to the left is a homemade low-battery monitor and Auto-Shutoff (after 15 min no activity) circuit that I added.  The main advantage to using this old radio circuitry is that it's all hardware (not software based as are more modern radios) and is relatively easy to understand and modify.

My first thought on interfacing the radio Rx to the mill was to use servos and micro-switches to control relays tied to the various mill functions, but a test setup connected to the UP/DN on the mill showed the response time of this arrangement was just too slow...it was almost impossible to get the head to stop on the desired mark.    I posted a question on an RC forum about how to read the control pulses coming out of an RC Rx to control a relay and got a few suggestions:  hack a servo (use just the electronics inside a servo), use a low-pass RC filter (RC = resistor/capacitor; this actually worked but was too slow also) , use a PIC microcontroller (I ignored this response because I didn't know the first thing about a PIC).  I decided to just recreate the control circuitry found in a servo so, after some on-line research, I found a "typical" servo schematic and ordered a bunch of components from Digi-Key; voltage regulators, FET's, op-amps, comparators, bunches of resistors and capacitors.  I spent a couple of evenings experimenting and eventually had a circuit that would activate a relay "instantaneously" with the flip of a switch on the RC Tx.  Success!  If you can control a relay you can control just about any function on WM sawmill (accept for the feed speed of course).  But I then realized that the component count of the circuit times the number of relays needed to control the sawmill would mean the prototype circuit board would require hundreds of hand-wired connections.  Nope, not gonna do it.  So...I gave some more thought to the PIC microcontroller suggestion, did a lot of Google-ing, and ordered a couple of the PICAXE versions of the PIC to play with. 

Unfortunately, I had to set the project aside to take care of more pressing projects and...ten months later I woke up one morning and decided it was time to learn how to program a PIC.  After reading through the PIC programming manual, doing a little circuit bread-boarding and writing some simple code, I finally had it...a blinking LED!  Woop, Woop!  8)  Look, you have to take your victories where you can, no matter how small. :D


 


The next hurdle was to figure out the code needed to make the PIC read the RC Rx channels.  For those not familiar with RC, a "channel" refers to an individual control function.  A 4-channel aircraft radio would control the elevator, ailerons, rudder, and throttle.  Each channel is typically output to individual connector pins on the Rx, which would mean I would need to dedicate up to 8 pins on the PIC just to read the channel data.  This was a problem as the PIC I had only had 12 I/O (input/output) pins available.  After posting a few questions on the RC forum, I discovered that the Rx firmware could be re-flashed (by the user) to output all the channel data in a single stream on one pin, referred to as CPPM (combined pulse-position modulated).  After re-flashing the Rx, connecting the CPPM output to an input pin of the PIC, and after a couple of evenings of extreme frustration  I finally saw this on my computer screen:



 


I literally jumped up out of my chair and did a victory dance (sorry, no video).  I know it doesn't look like much but this is the debug window of the code editor showing the PIC code I wrote synced up to the Rx data stream.  This was the first time that I was sure I could actually make this project work.  The first number is the much longer sync pulse followed by the eight channel data pulses, each assigned to a variable name created by me in the code. FYI, the trick to reading the data stream was to run the PIC at its fastest speed, look for a very long pulse (sync pulse) and once found, do nothing else but wait for the first data pulse.  The time between the end of the sync pulse and the beginning of the first data pulse is very short and it is easy to miss the first data pulse.  This all seems dead-simple to me now but at the time there was an awful lot of hair-pulling and head-banging (and not the good kind).

From there it was just many, many evenings spent writing and debugging code,  building and trouble-shooting the circuitry needed to interface the PIC to the sawmill, and building a transmitter configured to control a sawmill.  The code to control many of the mill functions couldn't be much simpler:


*****************************************************************

AutoClutch:            ;Engage/Disengage AutoClutch

select case AutoCl
   
case <200 goto ReadChannels   ;invalid data, loop back
   
case > 900   
   low c.2            ;Disengage AutoClutch
   
case > 200
   high c.2         ;Engage AutoClutch
   
endselect

*****************************************************************



But for other things like controlling the speed and direction of the saw carriage while implementing auto-braking delays and soft-start, the code got "a little"  : more complex.  I don't expect you to read through the code but I just wanted to show how getting fancy with features can complicate things in a big way.  The code without braking delays and softstart would have been only a little longer than the above code.

This is only about 1/3 of the code for controlling the carriage speed and direction. smiley_dizzy


*****************************************************************
ForwardReverse:              

   ;SoftDuty = 375 = start reverse at 1/3 of speed range(661-233/3 + 233)
   ;RC MODE TIMER SETTINGS
   BrkTm = 20 MAX 125      ;25 ~= 1s
   BmpTm = 15 MAX 125
   SoftInc = 40 MAX 255      ;1s soft-start=661(full spd)-375(1/3rd of spd range)/25=11(SoftInc)

if Mode =0 then         ;Manual Mode brake timer settings
   BrkTm = BrkTm * 2       ;set to 2x RC mode value, max 255
   BmpTm = BmpTm * 2       ;     "          "
   SoftInc = SoftInc/2 MIN 1
            
   
endif

select case FwdRev               ;check FWD/REV state
case < 300   goto ReadChannels         ;invalid pulse length
      
      
case < 600      ;REVERSE, Dir = 1     Green LED, RLY1
         ;BrakeFlag:  0 = full braking required, 1= braking completed or
         ;short brake if changing direction
   
      
      if Dir <> 1 and BrakeFlag=0 then      ;if previously dir was FWD
                        ;and braking not complete
         if DelayCnt<BrkTm then
            
            pwmduty c.0,0      ;BRAKE
            low b.2,b.4
            inc DelayCnt
            
            
         else   
            Dir=1         ;set flag to REV
            BrakeFlag=1      ;set flag to braking finished
            DelayCnt=0            
            pwmduty c.0,350   ;set to start point
         endif
            
      elseif Dir = 4 and BrakeFlag = 1 then    ;if previous dir was a bump FWD then
            
            pwmduty c.0,0               ;short BRAKE
            low b.2,b.4
            pause 1000               ;pause 125mS
            Dir = 1
            pwmduty c.0,350            ;set to start point
            BumpCnt = 0
            
      else         ;previous direction was REV or NEU and braking complete
               
         high b.4            ;REVERSE
         low b.2
;         if SoftDuty < 661 then      ;soft start in REV
;            SoftDuty = SoftDuty + SoftInc MAX 661
;            
;         else
;            SoftDuty = 661      ;soft start completed, full speed
;            
;         endif
      
         pwmduty c.0,661
         Dir=1
         DelayCnt = 0
         if BumpCnt<BmpTm and BrakeFlag = 1 then            
            inc BumpCnt            
         else
            BrakeFlag=0      ;longer than a bump, set flag for long braking
            BumpCnt = 0
         endif      
   endif
*****************************************************************
   



This post is getting too long and I bet I've already lost a few readers so I'll stop here. For those of you that have made it this far, this "project" is already completed and working. I'll finish posting the rest of the story soon with more pics and a "high-quality" video to follow.  Thanks for reading.

     

[Magicman]

I read it, and await your next segment.   8)

[tnaz]

Great job.  Over my head; glad you had your victory dance!!! 8) 8)

[jmouton]

that is way over my head but sounds really cool,  hope to see some pics,,


                                                                                                                             jim

[Kbeitz]

Love it.... Just like programing in good old BASIC....

I see what my next project is going to be....

[autotomk]

    that is incredible   i have got to have me one of them:)   been thinking of some type of remote for some time now.  Up grade is out for me too and, the parts are just as expensive,  that is awesome.

    OK i have to drop this for now ,going on a camping trip, first in 6 years, with wife  ( i guess deer camp doesn't count, I think of her there??)  She says no sawmill stuff:(:(  Ill still be watching on my mobile, when shes not looking.  thanks for taking the time.

[Ga Mtn Man]

Thanks for your comments guys.  I will post the rest of the project sometime tomorrow.

Just to be clear, the video at the top of my post is of Dave Shepard's mill with the Wood-Mizer factory installed Wireless Remote.   

[Dave Shepard]

Very interesting project. Do you have any kind of set works on your mill? I really like my wireless.

[Ga Mtn Man]

I have the SimpleSet.  As pineywoods said in his thread, a wireless control without some sort of setworks is just about useless.

[Kbeitz]

I really like your setup. I went the cheap simple way. My remote only work the carriage travel.
These two pieces is all that needed for that.



 



 

[logs2lumber]

that is awesome  i work on things like that everyday.  What would be really cool is putting a plc base or SBC and optic scanner and have it run completely automatic so you could unload slabs and lumber by yourself . would like to see it run for sure

[bkaimwood]

No, that wouldn't be cool...you unloading slabs while the saw makes lumber?😞 Takes the fun out of sawing. You running the saw from a comfy chair, remotely, with some purple drank, while 2 other guys unload slabs and lumber? Now that's cool!!!

[Picky2016]

Touchėe bkaimwood, lol.

[WDH]

The next thing you know, Paul, you will have that thing flying.  No need to tow it to the jobsite anymore  :D. 

[Ga Mtn Man]

Funny you say that Danny.  I was thinking the other day that, at least with regard to the FWD/REV and feed speed controls, I have the sawmill equivalent of an Airbus airliner...  I move the controls and the computer decides what to do... and we've seen how that, on occasion, has gone terribly wrong.   Time will tell.

I hope to finish posting about the project sometime this weekend.  Power was out Thursday evening and family is in town this weekend.  Stay tuned.

[rjwoelk]

Amazing, but I will stay with my lt15, no electrical and computer issues.  :D

[Bandmill Bandit]

Your project is not only very interesting  and informative it is exactly what I am thinking of doing. I definitely want to know more when you are done. I want to make my hydraulics remote as well.

[POSTON WIDEHEAD]

Paul, I just read this. Sometimes I think you've lost your %@#*&$& mind......in a positive way.  :D :D :D

Good job brother. 

[YellowHammer]

Funny you say that Danny.  I was thinking the other day that, at least with regard to the FWD/REV and feed speed controls, I have the sawmill equivalent of an Airbus airliner...  I move the controls and the computer decides what to do... and we've seen how that, on occasion, has gone terribly wrong.   Time will tell.

I hope to finish posting about the project sometime this weekend.  Power was out Thursday evening and family is in town this weekend.  Stay tuned.

The next step is network connection and sawing the logs remotely from your easy chair.  Very nice build.

[Ga Mtn Man]

Paul, I just read this. Sometimes I think you've lost your %@#*&$& mind......in a positive way.  :D :D :D

Good job brother. 

I know I need help.  It is a sickness.  Is there such a thing as MMA (mill mod-ers anonymous).  :-\

The next step is network connection and sawing the logs remotely from your easy chair.  Very nice build.

Great idea! I will add that to my winter project list.

[Ga Mtn Man]

-part II-

To interface the PIC to the mill controls I used SPDT relays (22 and counting).  Most of the mill functions are switched between Manual and RC modes through "Mode Select" relays activated by a single "RC Enable" output from the PIC.  When in RC mode, the Guide and Debarker In/Out directions are controlled by H-bridge circuits made up of two of the above mentioned relays and the ON/OFF switching of the mill functions is handled by other relays, each one activated by a control signal from the PIC



 



I first attempted to control the carriage FWD/REV and speed in RC Mode using a "high-current" motor controller off of ebay.  It didn't last three cuts. >:(  I abandoned that idea and built an H-bridge using four high-current relays (two on each leg) and ran both manual and RC controls through it.  The FWD/REV drum switch and manual speed pot are now connected to inputs on the PIC and control in both manual and RC mode is done through the PIC.  An analog output from the PIC feeds the stock Wood-Mizer PWM board now instead of the manual feed pot.  This allowed me to implement automatic braking delays and soft-start in both manual and RC modes.





 
Controller board all wired up. The four dark colored relays are the H-bridge for the carriage FWD/REV.   



 
All buttoned up.  Made this temporary panel so as not to mess up on the WM sheet metal.



 
Wiring in the 16-channel relay board ($17 on ebay)  Looks like my control box threw up!



 
The relay module fit nicely under the SimpleSet housing.   If it hadn't, I have no idea where else I could have put it.  Sixteen relays didn't turn out to be enough so I added the 4-relay module shown in the first pic.


Laying awake thinking about this project one night, it dawned on me that  I could put more than one control function onto a single channel of the radio system.     Because the "channels" are analog, they can be divided into levels that can be used to control more than one function.  This allowed me to free up a channel which made it possible to add full control of the SimpleSet functions.  :laugh:


This is the SimpleSet control board and H-bridge module.  If you look at the upper-left corner you can see a 5-pin header that I added in parallel with the ribbon cable that goes to the front control panel of the SimpleSet.



 
Here's the ribbon cable connected to the header.  The other end goes to the relay module.


Gotta get on the road early tomorrow so gonna quit for now.  Sawing in Kennesaw tomorrow.  Will finish up this thing soon
 



 



 

 

[TimGA]

Paul,
              Impressed is an understatement, I knew when we talked about this it was way over my head. I don't understand Greek soooo I just looked at the pretty pictures.   Great job.
                                                          Tim

[Bandmill Bandit]

When you're all done could you replicate that into an after market package I could buy from you and install myself? I am sure there will be others that would be interested as well. 

[Ga Mtn Man]

part III




 
Inside the ruggedized transmitter box.  The wiring harness was given to me by a customer who had salvaged it from a projection screen TV... made for a much cleaner wiring job than individual wires.   The battery pack is made from NiMh cells from Amazon.  The die-cast aluminum enclosure is made by Hammond Mfg.




 
You can see the speed control pot in the lower right.  The two square black things are the joystick modules used to control FWD/REV//Debarker In/Out and Up/Dn//Guide In/Out.  The little copper-looking metal strip in the center of the left joystick is a piece of spring steel that I installed to give the FWD stick a detent.




 
The completed transmitter with switch guards fabricated from aluminum rod.


System Specs and Features:

•   Remote control of all sawhead functions including SimpleSet and Lube-Mizer.

•   Auto-Braking Delay--- stops saw carriage before changing direction.

•   Failsafe Shutdown--- stops carriage, disengages AutoClutch and switches to         manual control mode if data link signal strength between sawmill and transmitter drops below a safe level.

•   Mode Change Safety Interlock--- inhibits switching from manual to RC or RC to manual control modes if any safety-critical control (carriage forward, AutoClutch, Debarker) is engaged.

•   Auto Transmitter Detect---detects signal from transmitter and enables/disables RC Mode.

•   RC Mode Override Switch---switch (located on  sawmill control console) overrides the  Auto Transmitter Detect and switches to manual control mode.  RC mode can only be re-enabled by turning transmitter OFF/ON or by switching the mill OFF/ON.

•   Range: >300 ft with no external antenna.

•   Transmitter battery run time: >10 hrs

•   Transmitter Auto Shutoff:  shuts off transmitter if no controls are moved for 15 minutes


Here's a video of my first time using the remote control at a customer's site.  It was shot by the same guy that gave me the wiring harness.

https://youtu.be/SGSdl2Xoco4






   

[WDH]

That is simply amazing to me.