Means of Measurement

Projectile Detection  
Velocity Capture       
Data Analysis           

Projectile Detection

Projectile speed capturing first starts with detection.  Here are some of these methods.
Electrical contact  -  projectile contacts wire within the barrel.
*  Contact switch     - projectile contacts the lever of an outboard switch.
Optical                  - projectile interrupts the optical beem between a transmitter and receiver.
*  Inductive               - projectile passes through a coil and produces an induced voltage.


The next step in speed capturing is timing.

Next ~~>  Velocity Capture

Velocity Capture
After detection is established, the issue of timing must be addressed.  Velocity is measured by dividing distance over time.  Distance is derived from the space between detectors.  I use this distance because it is constant, unlike the varying lengths of different projectiles.

Velocity capturing is completed by a timing mechanism.  The timer starts counting on the first trigger pulse from the detectors. 
The second trigger pulse from the dectectors stops the timer's count.  Now all is need is to divide measured distance by measured time.          V = distance / time    (meters / second)

PIC Code:  cg-rs232.asm         PCB image        ACG Chronograph image
Schematics:  velo-a  velo-b   velo-layout
Timing diagram:  benefits of dual detection

The next step is data calculations

Next ~~>  Data Analysis          Projectile Detection  <~~Back

Data Analysis
    After velocity is established, kinetic energies are calculated with the proprietary program Coilgun Acquisition.  The program receives the captured timing from the Microcontroller.  This measurement is combined with the distance between the sensors according to user input.
    Results show measured speed in meter/sec and feet/sec, projectile kinetic energy, and efficiency between capacitor potential and projectile kinetic energy.  User may select velocities in km/hour and miles/hour as well.

     I am now distributing ACG Acquisition as freeware and producing PIC timer boards, presently Velo5.

End          Velocity Capture  <~~ Back