Any Electronics Gurus Out There?

[quicksandfarmer]

Some more investigation reveals that the reading between all possible combinations of the four pins shows voltage of 6.5 or 7.5 VDC. These readings DO NOT CHANGE regardless of where the laser is striking the receiver and which arrow is flashing.

There are eighteen receiver diodes at each of the four corners of the receiver "feeding" the five output flashers. The distance between diodes increases, probably exponentially, as they progress away from on grade. It's interesting that when dead center on grade the flasher is at slow rate and when moving even 0.040" off center, the flash rate increases dramatically.

Looks to me that hacking this in an "analog manner" would involve picking up the output from each of the 18 x 4 = 72 diodes rather than the "flashers".

That would be consistent with it being some sort of serial signal, it would be bouncing between zero and one so quickly that the voltmeter wouldn't detect it. An Arduino has interfaces for most of the popular serial protocols, it's not hard to hook it up. The trick is in figuring out which protocol it's using. The easiest way is just to find out from the manufacturer by reading their technical manual. Often times if you look at the circuit board it will say on the board what it is, like "RS232" or "I2C" or "USB." Failing that an oscilloscope will tell but you have to have one and know how to use it.

Unless there were no other options I wouldn't try to read the 72 sensors directly. I suspect there is logic on board that is taking the readings from all 72 and combining and distilling it into a single number. If you read them directly you're giving away that functionality.

 

[npalen]

I see what you're saying. I wonder, in the scheme of things, whether picking up the flashing frequency of the LED's would be possible? That might be beneficial in knowing how much (or how many) solenoid on time/off time(s) is needed to get to grade level without overshooting.

Edit: A little overshoot wouldn't be such a bad thing, would just need to correct with a little reverse. I haven't ordered a solenoid valve yet but it would be useful even in manual control using a "joystick" for up and down.

 

[npalen]

Another approach to the means of actuating the cylinder is a power steering valve as shown in the attached. It is a basic Char Lynn four ports; pressure and return and A and B ports to the cylinder.
This type of valve is used on a large percentage of compact tractors and is connected directly to the steering wheel as I'm sure most of you are aware.

I had purchased and mounted this valve just to the right of the other remote valve bank as seen in the pic and done early testing with it to follow the laser receiver. My reasoning is that the rotary motion of the crank input would have the same feel as a steering wheel and the speed of the cylinder can be controlled by speed of the rotation. (The crank next to the seat works favorably from an ergonomic standpoint.)

I've been using one of the remote valves lately while waiting on a detent kit to make it easier to switch back and forth between the Char Lynn and any of the remotes or 3PH. (No power beyond on the Char Lynn)

So what I'm wondering is if it would make more sense to drive the Char Lynn with a variable speed 12VDC motor and worm drive gear reducer. That is how many of the ag tractors have been set up for GPS auto steer retrofits. The DC motor/gearbox output drives the steering wheel by friction around the circumference. Interestingly enough, the manual method of doing this is a GPS light bar mounted on the tractor hood and the operator watches the light bar and steers manually.

The power steering valve has the advantage of being proportional in that the faster you turn it the faster it "steers". So by varying the output voltage and polarity to the DC drive motor we could modulate the response to the laser receiver output.
The steering motors can be bought new in the $400 price range which isn't bad considering they have a built in subplate for the ports. A solenoid directional valve normally requires a subplate for mounting and plumbing.

So what do you guys think? I had kind of forgotten about using the Char Lynn so sorry about not mentioning it sooner.

 

[quicksandfarmer]

I think there's an asymmetry between up and down with a box blade, when it's floating it goes up if you lift it but it's as down as it goes. To make it go down you have to give it more tilt so it digs in more.

 

[npalen]

I'm afraid you completely lost me on that.

 

[quicksandfarmer]

I'm afraid you completely lost me on that.

I'll try again. The way I use the box blade is I have the 3 point hitch lowered to the point where the blade is floating on the ground. If I need to raise the blade I lift up on the 3PH and it raises. But if I need to lower the blade I can't just lower the 3PH more, because it's already floating. The 3PH can't apply downward pressure. Instead I have to change the angle of the blade so that it digs in deeper. My point is that raising is not simply the opposite of lowering.

 

[npalen]

I'll try again. The way I use the box blade is I have the 3 point hitch lowered to the point where the blade is floating on the ground. If I need to raise the blade I lift up on the 3PH and it raises. But if I need to lower the blade I can't just lower the 3PH more, because it's already floating. The 3PH can't apply downward pressure. Instead I have to change the angle of the blade so that it digs in deeper. My point is that raising is not simply the opposite of lowering.

Sounds like you have a fairly light box blade. Mine will usually stop the tractor in its tracks if I drop the blade too much. The exception would be extremely hard packed dirt and that's when the ripppers are used to loosen things up a bit.

 

[npalen]

Blec Laser Grader 15 - YouTube

Video of a laser grader with self-contained hydraulic power unit. Shows utilization of ripper shanks.

 

[quicksandfarmer]

I see what you're saying. I wonder, in the scheme of things, whether picking up the flashing frequency of the LED's would be possible? That might be beneficial in knowing how much (or how many) solenoid on time/off time(s) is needed to get to grade level without overshooting.

Edit: A little overshoot wouldn't be such a bad thing, would just need to correct with a little reverse. I haven't ordered a solenoid valve yet but it would be useful even in manual control using a "joystick" for up and down.

I think you're better off trying to read the signal directly from the remote out port than trying to read the LED's. Looking at the manufacturer's website it says that the receiver provides power for the remote. So of the four connections, one is power and one is ground. Just need to figure out what the other two are. If it's RS232 one is send and the other is receive. If it's USB one is plus one is minus for the signal.

 

[npalen]

In doing a little reading on RS232 and USB, my understanding is that USB uses software and an oscilloscope is unable to pick up the data. Is that correct and so would it be nearly impossible to reverse engineer?