After target lifts, it can be hit within a few 1/10 sec., so lifter needs to out of the way quickly. Might use a moveable pin, withdrawn by a solenoid untill target falls??-- ? How fast does spring return cyl. retract?

 

After target lifts, it can be hit within a few 1/10 sec., so lifter needs to out of the way quickly. Might use a moveable pin, withdrawn by a solenoid untill target falls??-- ? How fast does spring return cyl. retract?

That is a rare event that shouldn't have a lot of money sunk into, though it could cause a ricochet if cylinder is still in contact while plate is hit with subsonic pellet. If it becomes an issue, I'd suggest adding piezo sensors for feedback and a scoring system/"shoot/no-shoot" display system to work around it. Range rules should be set up to not shoot target until 1 second after reset, or run one 'stage', let them reset, etc. It's up to the designer to decide how to run the range.

Air cylinders are quite fast, 1/10th second is about right, even for heavy steel if the hinge hasn't been slowed by a bullet/pellet impact. With supersonic pellets (high powered air guns, 22LR), the lead bullet essentially turns into liquid on impact and works it's way through any/all cracks with a "splash" effect. Reason to have a 45º angled iron in front if hinge, so any ricochets go straight up or into ground rather than back to shooter.

The pellet/bullet will follow the steel a very short distance while tipping over, thus pushing any ricochet upward, or "splashes"/disintegrates if velocity is high enough. Lower velocities tend to produce more ricochets. Never use Steel BBs, they act like super-balls when hitting steel!

1 million frames per second bullet impacts on various materials (mostly supersonic rifle). Demonstrates splash effect extremely well. (handgun bullets and shaped charges at 2 minutes in, pellets at 4 minutes in, ballistic gel at 5min, steel plates at 6min again)

 

Bernard spring return on the air cylinders are super quick like "thatoneguy" says. Great video link on Bullet Impact "thatoneguy"

Bernard a drawing sketch of the mech attached to the air cylinder will give me some ideas.



RJ

 

Here is the code to withdraw the cylinders after ½ second so they aren't holding the target up the entire time. Forgot that part.

Addition is the last 3 lines before "goto main"

Once system is built, the ½ second delay can be reduced to match actual time taken to reset targets (probably closer to 100mS, but playing on safe side)


--ETA: Come to think of it, additional magnets will be needed to keep power to the acutator for the entire stroke. The magnetic switches will override any output from the PICAXE, that's why I didn't have it in the code earlier, so perhaps it doesn't matter.

#picaxe20M2

; More info at:http://forum.allaboutcircuits.com/showthread.php?t=77919
; 
;  This code may be re-used, modified, and shared by anybody, as long as  the information and credits above are not altered or removed.
; Please post improved code ideas and updates to a thread in the electronics chat area of allaboutcircuits.com
; Have fun, remember to wear eye and hearing protection when shooting!



;declarations
dirsB=$FF  ; All port B pins to outputs (20M2 pins 11-18)
dirsC=$0F  ; first 4 ports of port C as outputs (20M2 pins 7-10)
pinsB = %00000000 ; Reset all port B Pins to 0
pinsC=$00        ; Reset all port C outputs to 0

;variables
symbol delaytime = w0  ;delaytime variable  random requires word variables
symbol outs = b10     ; outputs
symbol adjust = b11    ; Potentiometer connected to C.7 (20M2 pin 3) to adjust delays

;initialization

delaytime = $1F         ;seed pseudo-random generator
;main loop
main:


readadc c.7,adjust    ; Pot connected between V+ and Gnd, wiper connected to C.7 (20M2 pin 3).  Used for adjusting random timing.
adjust = adjust * 100   ; make 0-254 number 0-25400 

random delaytime      ; get pseudo-random number between 0 and 65535
delaytime = delaytime % 7000  ; Mod 7000 to get number between 0 and 7000
;delaytime = delaytime + 3000  ;add 3000 for 3-10second delaytime (depreciated by user potentiometer addition)
delaytime = delaytime + adjust ; add user chosen delaytime to delay.

pause delaytime          ;pause for 0-26,100 milliseconds (0-26 seconds, user set potentiometer + 0-7 seconds)

random delaytime        ; get new random number for output states
outs = delaytime/256   ;use first 8 bits of delaytime word for random port b outputs
pinsB= outs           ;set portB pins high or low psuedo-random (20M2 pins 11-18)

random delaytime         ; get new random number for output states
outs = delaytime/512    ;use last 4 bits of delaytime word for random port c outputs
pinsC= outs           ;set portC pins high or low psuedo-random (20M2 pins 7-10)

pause 500              ;wait ½ second to ensure all chosen targets to reset are up
pinsB = $00              ;disable outputs after the ½ second delay so cylinders aren't pushing on target
pinsC = $00              ;disable outputs after the ½ second delay so cylinders aren't pushing on target

goto main               ; keep doing it until power is removed.

 

Are air cyl. push or pull?, maybe either?

 

Looks like my post went up in smoke?? To short on time to start over. Figure less than 8 lb force will do.

 

Bernard I have the "push" types single and double action air cylinders. Do you think the "pull" types spring return air cylinders take less space on the platform? So your sketch is based on a 1" stroke cylinder correct instead of a 3" air cylinder correct? Im trying to reduce the space to as small and compact as possible. Attach is an image of the 1st model, it has been completed. This model is manual by RF remote control.


Parts List:


-a sheet of plywood
-hinge
-coat hanger
-paper clips
- 3" inch single action spring return air cylinder
-24 V air solenoid valve
- RF remote & receiver.

The 2nd model I will build the electronics will be a PICAXE instead of it being RF remote control. It will pop up the target automatically at a random time.


I would also still like to make another version out of a DC motor self contained with its own build in battery pack.


I like the pneumatic system because the air cylinders are weather proof but I need an external air supply. From my experiments I need at least 40 PSI to activate the mechanism. I wonder if there is a small compact self contained air compressor that can put out that much pressure that I can make it self contained instead of using an external air supply.


Any ideas, suggestions, comments are welcome


RJ

 

I much prefer the 3" push, single action spring retunn cylendar; I picked the 1" stroke as a worst case with future heavier target in mind & I had a picture of one. Some dimentions of the 3" stroke would be helpfull.

 

Im using a 3" inch Bimba single action spring return push cylinders 7/16" inch bore in this model. Very thin, moves just nice with 40 psi. I just wanted to keep my platform as small as possible. I was even thinking about doing a model with the electronics box, battery pack, DC motor right below the mechanism. Basically instead of the movable mechanism being on the side which takes a lot of space, I wanted it below but I can't think of a mechanism now to do this kind of setup. If you have any ideas how to stick the mech below instead than on the side let me know. This model I made is a very simple setup model with just a few parts being used.


I can't wait to receive my PICAXE package in the mail to complete project model #2



RJ

 

Looks good. You would probably want to add armor to the cylinder/control/box/air line. A pellet would punch through your project enclosure and air line without a problem. A .22LR would cut through the lift bale as well.

An air source is a bottle of CO2 w/regulator from welding supply, that would last a long time, provided you had absolutely no leakage.

Another option would be a mini-compressor that is provided with most cars today. Those can do the PSI, but if you added an accumulator (air tank), that enough pressure/volume to run all actuators at the same, the portable pump would work. Though "Portable" is a term very loosely used, as you would need a 1 gal or so air tank, valves and connectors, line dryers, and deep cycle 12V battery to power compressor.

 

THANKS "thatoneguy" I've put a temporary steel plate in front of the plastic project box to protect the electronics inside when running the test. If I puncture an air hose line that is cheap to replace but I can run it low inside a metal tube to protect the air line, that's no problem. I though of maybe using a 20 OZ paintball CO2 tank as the air supply with an adjustable regulator on it. Im wondering if there is a low pressure adjustable regulator that i can fit to that paintball tank, if you know of a place I can purchase one of those low pressure adj. regulators for paintball CO2 paintball tanks email me a link of where to purchase one THANKS. Also if anyone knows of an online store where I can purchase pneumatic fittings and hoses for real cheap let me know. I can even go with plastic fittings instead of metal fittings which should be a lot cheaper.

The compressor, large battery, and large air tank in combination would take too much space for the single target model.

The other model I plan to build is a multi-target not a single one like this one. The single target needs to stay as small as possible and ran as stand alone without nothing being attached to it since I want the single target model to be portable and can place lots of them all over the field.

The Multi-Target model can have external air supply and external power.


"thatoneguy" let me know if I can use the PICAXE in a certain configuration to run a DC motor instead of the solenoid air valves, I am aware there will be more circuitry involved. I need the DC motor to have forward, reverse and stop and will need to use 2 limit switches one to tell it when its up and another when its down. The DC motor I will be using will be a geared motor powerful enough to stand up the target. I got them in the other day. The one I plan to use now runs low RPM's, more powerful than the previous one I was using which I stripped the gears on and this new one I got operates at 12VDC instead of 5VDC.


Let me know if you can help out with the circuit to run that 12VDC geared motor using the PICAXE configured for forward, reverse and stop in Random Mode. I needed the program random just like the previous program.


I also though of when using the DC geared motor instead of using limit switches to make a circuit where it will detect current instead. When it reaches the limits up and down the motor will draw more current than normal and just stop automatically. Similar to the circuits used I think in automatic power windows of aftermarket car alarms where when it reaches its limit it automatically cuts the relay.


Any suggestions, ideas, comments will be helpful



RJ

 

Outline of below deck air cylender mounting. Requires a slot in deck for lifting arm.
Source for fittings air regs etc is www.surpluscenter.com

 

Bernard. I like the sketch below deck. Mech looks more complicate than I though. Email me a private message when you can.



RJ

 

If I were building this, think arm would be made in two pieces from 24 ga galvanized steel, finished parts formed into U 1/2 wide all the way , web 3/16 cut away on each end for wheel & pivits. Both sections soft soldered together. Buttom shaft support L shaped bracket or 2 wood blocks.

 

Bernard as long as the mechanism is compact, sturdy and durable it should do. Keep me posted on any other mech ideas below deck.

If someone knows how to set up a PICAXE configured to drive a DC motor to do forward, reverse and stop let me know.


RJ

 

Here's an outline of a DC operated, below deck target lifter. Actuator is not based a known model, but price might be in $ 70 to $ 90 range. Target is lifted by spring power & reset via actuator. When reset target is lifted by energisong solenoid. Most actuators have built in limit switches which can be used if stroke is in proper range.

 

You'll need an H-Bridge to drive a Motor w/PICAXE. Something like an L293N (<2A motor stall current). An H-Bridge typically needs two wires to control each motor, but with limit switches, there's a way you could invert one of the signals to control both inputs and limit switches

May be simpler to offload motor driver control to an 08M2 picaxe that reads the output of the random PICAXE and input of switch to run a motor driver.

The circuitry gets a lot more complex once you move away from an air cylinder with return spring.

 

OK will start working on this. THANKS for all your help.

 

"thatoneguy" I programmed the PICAXE 20M2 with the last source code you provided me with and put it to the test. I have no outputs on B6 or B7 for some reason all the other 10 outputs are working fine. Any suggestions?


RJ

 

I only ran the simulation of the code, there may be certain registers to disable in the code for B6 and B7 (Which are usually PGC and PGD for ICSP programming of the PIC, NOT For PICAXE programming!)

Look at an example that uses B6 and B7 as an output, and see if the initialization/port setup code is different, and verify they function on the board you are using.