When I started intermittently assisting as a contract instructor in 2005, it had a rail-mounted moving target system provided by a commercial supplier. The manufacturer provided only a wired control system for the motor. Since Rifles Only is primarily a precision rifle facility, using a wired system required a person to run the moving target who could not be where the students were shooting. The operator had to sit in the sun behind a berm, serving only a single function in an uncomfortable environment.
Attempts to convince the manufacturer to provide a long-distance wireless control system elicited promises which remained unfilled for many months - in fact, that manufacturer to my knowledge still does not offer such a system. Promises were made - and broken. As the junior instructor on the facility, I was often the person sitting in the pit running the mover. As a happily retired electrical engineer, I didn't wish to build one - but I finally decided sort of in self defense that doing so was preferable to sitting in the pit.
The system was provided with a wired control system with documentation which did not explain how it worked. It took a while to figure out how it worked, and how to interface to it to make it run back and forth and to stop it. We did not deem it necessary to change the speed on the system remotely, only to run it.
That was done. A four-channel commercial handheld transmitter and receiver were purchased, which operated on 27 MHz frequecies using digital FM FSK encoding. The advertised range of up to 10 miles line of sight greatly exceeded the requirement. Also purchased were power supplies with battery backups, and limit switches to stop the target at the ends of the rail if the operator did not stop it manually. I built a breadboard for the eventual system shown in the picture below, although the original motor controller provided by the manufacturer subsequently failed in service and was replaced with a commercial motor controller. (Yes, there is a mud-dauber nest sitting atop the lower battery in the picture.)
I designed the original system around resistor-transistor and relay logic, the parts for which were all available at a local Radio Shack, the idea being that failures could be more easily repaired with locally procured parts.
The circuitry is simple. The wiring is very crude - this was intented to be a proof-of-concept prototype for the final system, which would be cleaner and more elegantly packaged. However, once in operation, the system provided so essential to day-to-day operations of the training facility that it was left in place where it remains to this day. It allowed us to operate the moving target system out to the the maximum small arms distance. Later, a circuit to control a pneumatic turning target system was added to the fourth channel of the transceiver pair.
For six and a half years, at the time of this writing, this system has sat in an uninsulated plastic box in the Texas weather, without a single component failure in the control system.
That system worked fine, although the reed relays required replacement after a mouse got into the control box and chewed through the plastic cover of the reed relays, causing short circuits.
As Jacob is my very good friend, as well as having saved me from a life of dissipation and probable alcoholism by providing me with work to do, when he asks, I deliver, if I can. There was no question whether I could, only of how.
I had recently run across an article on the Arduino microcontroller in a magazine. They are incredibly inexpensive - far less than the bottles of Scotch to which I have become addicted due to the efforts of a couple of my friends who are emergency room physicians in public hospitals in a large metro area, and thus have an appreciation for the anesthetic effects of fine whiskey.
The Arduino Uno has 13 digital input/output lines, and six analog inputs. A free downloaded integrated design environment (IDE) makes it possible to write code for the Uno in the C programming language, compile it, and download it into the flash memory of the Arduino connected by a USB cable for execution. That makes program development quick and relatively easy if you already know C, which, in the far distant past, I did. Considerable experience in how easy it is to write really awful code in C kept me from doing so, fortunately.
A geek friend commented that it was incredibly backward of me to be writing in C. I agree, although my invitation to write a Pascal or Ada compiler for the IDE has so far produced no results from him. But for small projects like this one, C is usable with care.
The addition of a stackable prototyping board with a couple of transistors and other components shown in the picture below, completed the hardware. The digital switch allows selecting the delay period at each end of a run in autocycle mode.
Visiting range owners have expressed an interest in acquiring a copy of the earlier systems. I have resisted providing them. I have better things to do, and I doubt that any rational person would offer me funds sufficient to entice me into a business from which I was blissfully happy to retire more than a decade ago. However, not everyone I know is rational.
But I'd rather be training shooters - or hiking in the mountains, and producing systems like that also imposes the burden of supporting them. I'm really not interested - sorry.
Generation Three Update
During a Precision Rifle Class on November 30, 2011, one of the two power supplies of the Gen One system failed. Since the replacement board for it was already under construction, it was removed and replaced with the Gen Three Mod 1 system. It survived six and a half years in service. All original components of the control system itself were still operational without modification.
Gen Three Mod 2 was completed on December 17, 2011. Mod 2 was constructed on a Prototino board. While successfully constructed, it was a pain to build because of the small size of the board - two relays are mounted on the bottom size of the board. Since there is no real need for miniaturization in this application, Mod 3, which will be the spare system, will be based on an Arduino Uno board, with non-digital components mounted on a separate board for ease of construction and testing.
The smaller control package makes for a much cleaner installation.
Gen 3 Mod 3, based on an Arduino Uno board with an external component board, was completed on January 9, 2012, and installed. On the same date, the box containing Gen 3 Mod 1 was sealed, and it will be kept in inventory as a spare system, with all connections external to the box, as are Mod 2 and Mod 3.
During the week of March 12, 2012, the spare system was put into service to control the second moving target system installed on the main mover berm in parallel with the first system. So far, the management has not decided to build a complete spare system. Since there are now three identical and interchangeable systems in service, the requirement for a spare system may be a low priority. The power supply, radio receiver, and motor controller are all easily obtainable from established vendors. The processor system, however, is not. Accordingly, I began building a spare processor module, which is now complete, and ready for installation if necessary.
Gen 3 Mod 4, based on a Prototino board with an external I/O board.
Generation Four will be the Internet-connected Iphone app...
lindy@arcanamavens.com
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© 2011, 2012 by Linden B. (Lindy) Sisk