Remote Touchscreen-Controlled Defense Turret Senior Design Documentation Courtney Mann, Brad Clymer, Szu-yu Huang Group 11

USB 2.0 Hi-Def

Next considered was a line of uEye USB cameras available from IDS Imaging (IDS Imaging), with very high frame rates. These cameras were all connected via USB, as the heading suggests, so power was not a primary consideration when comparing them. All cameras were 640x480 pixel resolution; the primary differences between them were the frame rates and mountability; the group did not seek to explore custom mounting hardware at extraordinary depth. The UI-2410ME with USB 2.0 interface features a CCD sensor from Sony. It has a remarkably high maximum frame rate, 75fps, and is manufactured with six mounting holes such that it could easily be screwed into wood or bolted to a steel frame. Compared the other options, this was a reasonable choice without price considerations; pricing was not available at the time of this writing, so it could not be reasonably compared.

Also from IDS Imaging, the USB 2 UI-1225LE-C was under consideration. This camera has a resolution of 752x480, a maximum frame rate of 87 fps, and a small footprint as well as low weight. The resolution of this camera was deemed acceptable, and the high frame rate was desirable, but there is no existing mounting hardware, so upon consideration it was ruled out. The UI-2220ME-C is nearly identical to the first-considered UI-2410ME, except that this model has 52 fps and a resolution of 768x576, and it is also available in a black-and-white version, which offers the fetching quality of potentially much less data process demands, but which does not allow for the attractive user interface that the group desired. Aside from the aesthetic quality, having color enables a user to more easily distinguish between targets, so the black-and-white option was ruled out. The footprint of the UI-2220ME-C is identical to the UI-2410ME, so mounting concerns were obviously low, identically to that model.

The UI-1120ME-M has the same footprint as the above model, but offers an interesting bonus: this model operates in the visible spectrum, but also operates well into the IR spectrum, which would potentially allow the group to investigate both of these options in one camera and compare the results. The UI-1120ME-M features a resolution of 768x576 and a frame rate of 50 fps; so, without the IR option, it is very similar to the UI-2220ME-C.

Some higher resolution cameras were investigated as well. For example, the UI-1640SE-C, which has an Aptina CMOS sensor in 1.3 Megapixel resolution (1280x1024 pixels), also from IDS Imaging. The high resolution apparently limits the frame rate available on this model and several others in that resolution range, as the highest available was 25 fps. The group was unsure as to whether this would be below the minimum frame rate needed, but it was determined that gambling on such an item working was a poor design decision. The casing of this model also did not lend itself well to mounting. While there were other models of similar resolution available and better mounting options, none had a frame rate with which the group was comfortable, so it was decided that these would not be used, and that frame rate was a higher priority than high resolution.

11. Power Sources

The power sources investigated were batteries, solar power, wall AC, and generators. Each of these has their own advantages; a summary of the group’s research is shown below.

Batteries

Because of the different firing platforms considered, there was a multitude of battery types that had to be considered to power them. The types of batteries considered are: alkaline, nickel-metal hydride, nickel-cadmium, lithium-polymer, metal-chloride, zinc-air, zinc-mercury oxide, and silver-zinc.

Although disposable, alkaline batteries are the most common type used in small household gadgets and are supplanting carbon zinc and zinc chloride batteries as the most common technology. There is not much difference from brand to brand since each battery uses the same chemicals. Comparison tests was done by Consumer Reports between different alkaline brands and showed that the best and worst batteries only differ between 9% - 15%.

Rechargeable alkaline batteries have good capacity, but limited rechargeability. However, they do give out higher voltage than NiMH (nickel-metal hydride) batteries. This means that they perform well with devices that take in multiple batteries. For instance, LED flashlights produce brighter light with the alkaline batteries than with NiMH. Infrequent use along with high self-discharge of can make NiMH batteries go dead on their own between periods of use.

NiMH batteries offer great capacity and long recharging life, but are slightly more expensive than alkalines. One possible downside with the NiMHs and NiCads (nickel-cadmiums) is that they both put out less voltage in comparison to alkaline batteries. This means that devices that work with multiple batteries may not work with NiMH or NiCad batteries. Another downside with both batteries is that they quickly self-discharge so they lose power even if they are not being used. A positive distinction about the NiMH battery is its discharge path when compared to alkaline. The voltage and current of a NiMH starts high and does a good job of holding this rate for about 75% of its battery use; the current will then will gradually diminish at the end of the battery’s capacity.

NiCad (nickel-cadmium) batteries deliver good capacity, long life recharging, are an economically conservative rechargeable battery. NiCads have approximately 25% less capacity than NiMHs; a NiCad Sub C cell can be 1200 or 1800 mAh while NiMH battery starts at 2400 mAh and goes as high as 3800 mAh. NiCad has higher current delivery per cell however, having 3 units as opposed to NiMH which has 5 units.