The project started as something to meet a bunch of requirements for a mechatronics class and now is an able blimp platform capable of maintaining its own altitude and finding an infrared beacon.
Here are some pictures of it in action. Excuse the balloons, we couldn't buy a suitable envelope, so we bought one that was too small and added latex balloons. I am currently in the process of designing a correctly sized envelope and it should be put back together for some final testing. The entire project took us less than 8 weeks and less than 100 man hours. It looks like hell but it works and we're pretty happy about that. (Happy = good grade!)
Here is the blimp from a few feet off. As you can tell the envelope was way too small for our control system.
This is a close up of the control system. The RC controls were implemented using a RF Serial Link from spark fun. Everything else is fairly similar to BlimpDuino except our altitude control was proportional only and turning was via tank controls (pivot turning I guess its called) instead of PWM.
If we were to do it again, we'd not use PIC's so we could use floating point math. Unfortunately PIC Microcontrollers were are requirement of the assignment.
Here is our transmitter. The transmitter has a lot of bells and whistles that were required for the assignment, but the real meat comes in the take off and land commands for autonomous mode so you can send it a little out of reach (I wouldn't though haha).
Other than that, in RC mode the keypad is linked to forward, left, right, and back commands.
Lastly, here is the beacon. The beacon sends a modulated 56 kHz signal which is picked up by the beacon. The pulses are counted and signal to noise ratio is used to determine which direction to go. If I were to do this again, I would not use a beacon and make it find walls, but that is for the next project I guess.
Hope you guys find this interesting. I certainly did.
Update 1-28-09 -- We built a new envelope today out of space blankets. Since we are poor college students, we ended up using space blankets and hot glue. Before you start laughing, let me tell you that it holds helium... well. We ended up making the envelope too big so we only needed to fill it about 2/3 the way and the center of buoyancy wasn't where we wanted so we added ballast in the form of a water bottle in the back. The blimp will be featured in an upcoming installment of Design News Magazine in the Gadget Freak's section. The photographer is coming tomorrow to take our pictures. I will update with photos of the new envelope sometime soon. In the mean time, the video has been posted and can be found here