Sentry Robot Turns Bad Cat to Good

The household of [James Watts] has cats, and those cats have decided that various spots of carpet are just great for digging up with their claws. After some efforts at training the cats, [James] enlisted a robotic cat trainer with remote wireless sensors. The automated trainer does only one job, but it does that one job reliably and tirelessly, which is just what is needed in this case. A task like “automate training the cats to stop clawing the carpet” is really made up of many smaller problems, and [James] implemented a number of clever ideas in his solution.

First of all, the need for an automated solution has a lot to do with how pets form associations, and the need to have the negative reinforcement be in the right place at the right time to be effective. A harmless spritz of water in this case is used for correction and needed to be applied immediately, consistently, and “from out of nowhere” (instead of coming from a person.) Otherwise, as [James] discovered, spraying water when the cats clawed the carpet simply meant that they stopped doing it when he was around.

There were a number of tricky problems to solve in the process. One was how to reliably detect cats actually clawing the carpet. Another was how to direct the harmless spray of water to only the spot in question, and how to rig and manage a water supply without creating another mess in the process. Finally, the whole thing needed to be clean and tidy; a hackjob with a mess of wires strung everywhere just wouldn’t do.

base_frontTo achieve all this, [James] created a main sprayer unit that is wirelessly connected to remote sensor units using NRF24L01+ serial packet radios. When a remote senses that a trouble spot is being clawed, the main unit uses an RC servo to swivel a spray nozzle in the correct direction and give the offending feline a watery reminder.

The self-contained remote sensors use an accelerometer to detect the slight lifting of the carpet when it’s being clawed. [James] programmed the MMA8452Q three axis accelerometer to trigger an external pin when motion is sensed above a certain threshold, and this event is sent over the wireless link.

For the main sprayer unit itself, [James] cleverly based it around an off-the-shelf replacement windshield washer tank. With an integrated pump, tubing, and assortment of nozzles there was no need to design any of those elements from scratch. If you want to give the project a shot, check out the github repository — probably worth it it since one night is all it took to change the cat behavior which explains the lack of any action video.

Pet projects usually center around automating the feeding process, but it’s nice to see other applications. For something on the positive-reinforcement end of training, check out this cat exercise wheel that integrates a treat dispenser to encourage an exercise regimen.

Airsoft Sentry Gun Keeps Your House Guarded

Ever since automated turrets became a thing in video games, people have strived to make their own — let’s be honest, who wouldn’t want an automated defense turret? Well, [Austiwawa] just finished making a pretty awesome Airsoft gun turret, and decided to make a video tutorial on how he made it.

The inspiration comes from Project Sentry Gun, a long-standing website dedicated to teaching people how to make automated sentry gun turrets. We’ve seen projects use this to turn Nerf guns into turrets, and people have even made their own paintball gun sentry turrets.

Following along the build only takes about 5 minutes of your time and summarizes the process very concisely. We particularly like the main rotation axis — one RC servo motor and 4 casters make up a controllable lazy susan that reduces the load on the servo motor and allows you to mount a pretty big gun on the turret.

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Raspberry Pi Sentry Turret Is The Enemy Of All Mankind

War, huh, what is it good for? Absolutely nothing, except as an excuse to build a Raspberry Pi powered sentry turret that will track and fire upon your enemies. That’s what [Matt Desmaris] decided to do, and he has released the full details of his build.

It lacks the polished elegance of most military hardware, but what do you expect of a quick and dirty hack? It’s not shiny or ominous, but it has that killer motion-tracking feature. [Matt] is using OpenCV to detect movement from a USB webcam, two servos to pan and tilt the camera and gun and a small relay to pull the trigger. Manual control over the Interwebs is also available.

We’ve seen lots of similar builds using weaponry such as rubber bands and Nerf guns, but this one is a great start if you are interested in seeing how you can tie together tools like OpenCV and servos to create a camera that actively tracks movement.

Arduino Powered Rubber Band Sentry Turret Is Not a Lie

You know that guy in the next cube is sneaking in when you are away and swiping packs of astronaut ice cream out of your desk. Thanks to [Kevin Thomas], if you have an Arduino and a 3D printer, you can build a rubber band sentry gun to protect your geeky comestibles. You’ll also need some metric hardware, an Arduino Uno, and a handful of servo motors.

The video shows [Kevin] manually aiming the gun, but the software can operate the gun autonomously, if you add some sensors to the hardware.  The build details are a bit sparse, but there is a bill of material and that, combined with the 3D printing files and the videos, should allow you to figure it out.

We couldn’t help but wish for a first person view (FPV) camera and control via a cell phone, so you could snipe at those ice cream thieves while hiding in the broom closet. On the other hand, if you got the gun working, adding the remote wouldn’t be hard at all. You probably have a WiFi FPV camera on your quadcopter that finally came out of that tree and there’s lots of ways to do the controls via Bluetooth or WiFi.

Not that you don’t have options. But here at Hackaday HQ, we have lots of rubber bands and not so many green pigs. If you’d rather shoot paintballs, be careful you don’t accidentally repaint the insides of your cube.

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Angry Birds Sentry Gun has Pigs Flying

[Farlei Heinen] has a C programming class at school. Not wanting to do another boring cookie-cutter project out of the textbook, he decided to do something different — he’s built an Arduino controlled sentry gun!

It consists of two parts: The sentry gun itself and a sonar detection tower which can tell if you’ve successfully knocked down the pigs or not. He’s using an Arduino Mega at the heart of the project, which controls the servos and reads information off of the sonar sensors.

The sentry gun uses two servo motors to control up and down, and left and right. The loading mechanism is manual, using elastic bands to launch the projectile. The firing mechanism however is a micro (9g) servo, which can release the elastic and shoot the projectile. The target is an Angry Birds toy play set made for kids.

It’s a pretty cool project, and [Farlei] has even released the source code for it if you’re interested in building your own — check it out in action, after the break!

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Open-Source Sentry Gun Plans Promise the Next Level of Office Warfare

We admit it, we were browsing Reddit when we found this beautifully hacked together Nerf Sentry turret. But are we ever glad we did — as it turns out, it is very similar to the totally awesome, open-source Project Sentry Gun.

We have actually covered a project that used that system before, but it looks like it has evolved a bit more since then. It’s just too cool not to share.

The system itself is quite simple and easy to build. You’re going to need three servo motors, an Arduino, a webcam, and assorted wires, nuts and bolts, etc etc. Grab a copy of the code, slap it all together, and you’re ready for business!

Just take a look at the following video of the Gladiator II Paintball Sentry Gun — we know you’re going to want to build one now.

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Nerf Sentry Gun for the Apocalypse

nerf-sentry

If you’ve ever wanted to shoot someone with a Nerf gun, but just didn’t have the energy to get off the couch, this hack may be for you. It’s also a good way to ward off zombies if another apocalypse, Mayan or otherwise, is on the horizon.

Although the effects are very cool, as seen in the video after the break, the method for making this setup was quite simple. The requirements for this project were that the gun could not be permanently modified, and everything had to fire automatically. These restrictions may have contributed to the simplicity of the design as many of us would start breaking things before we had to.

Instead of some elaborate hack, the trigger was tied back in the firing position at all times. A relay was then used to interrupt the power supply to the mechanism allowing an Arduino equipped with an infrared sensor to automatically control the firing. The setup is explained after the break, but skip to around 1:55 if you’d rather just see the guns in action. Continue reading “Nerf Sentry Gun for the Apocalypse”