Rocket 1.0
Hardly a robot but still smokin' cool

  Rocket 1.0 (yet to be named) get's its' start with a new launch pad.  The old one worked fine but I wasn't happy with it being sturdy enough so having my own welder and chop saw I went to work.  This basic stand allows the rod to be unscrewed for transport and is strong enough to support my weight but only weighs 2.6 lbs.  The remote control launch system is almost completed at this time.  The reciever on the launch pad has been built and tested and continues to use the same format you have come to see me use.  The receiver uses the new Linx RF modules from www.rentron.com and a PIC 16F84.  The transmitter will send serial data from my laptop serial port to the receiver on the launch pad.   When the correct signal is sent the receiver will close the contacts on a relay which will power two alligator clips, one on each of the rocket ignitors leads.  This will light the 'flare' that igintes the rocket engine.  This RF link is bidirectional and allows the rockets' onboard microproccessor to send back serial data that the laptop can record via the VB program I have written for it.  The launch pad guide rod also works very nicely for an antenna for the receiver module (not pictured).

   Also pictured on this page is the rocket itself, not quite the same one I had in mind during the original conception of the program but it will do for the first dozen or so lauches.  This rocket body is approx. 18 inches long and houses the typical parachaute and shock cord.  Added is the same PIC 16F84 that I love to use and it monitors G load, temp, and sunlight at this time.  Additional sensors may include a digital compass and altimeter.  For now the PIC just runs a cycle looking at G force, temp and sunlight and sends these values back to the laptop RF unit for recording during flight time.  The VB program makes the timing nice since immediatly after the 'Launch' button is pressed it begines recording incoming data.  The first incoming data packet is always the G force value and it is preceded with the ASCII letter 'G'.  The remaining two data packets are temp and sunlight and are always transmitted in that order.  This way the PC will not get confused as to which data packet it is looking at and where to put it. The sensors on the rocket are a CDS cell for sunlight measurement, a linear thermister to monitor temperature and a homemade G force meter that needs it's own paragraph just cause it's so cool and I though of it. 

    The G force meter used on the rocket is made from a linear pressure sensor available from www.Jameco.com .  The pressure sensor is able to sense pressures from 0.1 oz. to 16oz.  So by housing the senor in a square plastic tube and putting 1/4oz. weight above it I am able to provide a 'constant' against which to measure.  The pressure sensor is basically a linear resistor with a spring in it.  So by reading the resistance change of the sensor with the PIC we can derive a number between 0 and 256 that corresponds to the weight of the object on it.  The number we get from the PIC with the 1/4oz. weight at rest on the sensor is 18.  So that means we can read upto 14.2 G's of force.  (256 / 18 = 14.2) Again, when the rocket accelerates the force of the 1/4oz. weight against the pressure sensor increases, and as it increases the PIC is monitoring the change of the sensors resistance due to the G force that is developed by the rockets thrust.  That is my cheapo G force meter, probably not exact but hey,  this isn't rocket scien....

Pictured right is the control program that sends serial data to the launch pad receiver and also receives data from the rocket itself.  The serial port is selected by the user depending on which comm port is free.  The 'Initialize Comm Link' button sends a test packet of data that lights up a LED on the launch pad receiver to verify communication before a launch attempt.  On the rocket end of things, all we do is turn on the PIC and RF transmitter to start receiving data.  At this point the program does not log or record data but I have almost completed the new program which will..

Pictured below is the basic schematic of the Rockets Tx unit and PIC.  You will see the TX unit has a 430 ohm resistor on the Ladj pin.  This drives the TX input to work with 0 - 5 volt signals as opposed to 0 - 3volt levels when the 430 ohm resistor is not used.  All three sensors are shown and all three are variable resistors so it makes the code very repetitive but easy to work with.