Hi. This project is about robo trashcan, that will open its cap if you pass your hand above it. The trashcan will open its cap for 10 seconds ifyou place your hand from 10 to 30 centimeters above the cap, and for 3 seconds if your hand will be at the distance from 30 to 70 centimeters. This mode is for fast throwing things out. Also trashcan has a switch for service. So cap is open while switch is pressed.
You can watch all the process on my video
Step 1: All We Need
The brain of all system is arduino, so you can change all distances and times very easy, editing the sketch. The - it is a bucket for detergent. Sensor is cheap range ultrasonic sensor for arduino, and actuator is servo motor, all these components I’ve bought very cheap on aliexpress, links in the video's description. The connection rod I will make of paper clip.
• Arduino nano $2
• Range sensor $0.5
• Servo $1
Step 2: Developing a Mechanism
I get rid of all useless plastic parts from trashcan. I decided to design the can opening mechanism, so I measuring all parts of mechanism and sketching it on paper in real scale. Cap is showed in 2 positions, opened and closed. Mechanism is very simple: there is a hinge on the cap and connection rod to servo. But will this mechanism will enable to operate? Let's find it out, using the autodesk force effect motion.
iTunes download link
Google Play download link
I take a photo of my sketch and upload it in force effect application. In this application I can build my mechanism and explore it. Servo can turn on angle of 180 degrees, so cap can't close. I change some dimensions and mechanism works perfectly, I like it. Now, looking on this sketch, I make some corrections in my sketch. And using my sketch, i can find all dimensions by measuring them with rule! Now we are ready to build it.
Step 3: Making a Hinge
I will make a hinge from a tincan metal. Just cut off some strip, fold it and mark an axis. Bend some legs and make a hole for shaft. I just glue it to the cap, so process both surfaces with abrasive and glue.
Step 4: Mounting the Servo
Make a mark for servo's shaft place, like on the sketch. Temporarily attach servo with tape and mark 4 holes to fix a servo with cable ties.
Now I am making a connection shaft of huge paper clip. Insert it in hinge and servo. I’m finally bending paper clip to fix it.
Step 5: Mounting Range Sensor
It's time for the range sensor. Get some dimensions and mark them on the cap and make necessary holes. Connect wires to sensor and fix them all on cap with hot glue.
Step 6: Button
Make a hole for switch on the side of your thrashcan, solder wires and place button.
Step 7: Schematics and Sketch
So, you can change all distances and timings in the sketch. Also, measuring of distance is arithmetical mean by 3 metering.
Step 8: The Rubber
You can see that servo is weak, so closing of the cap is faster than opening it, it’s because of the gravity. Let's fix it with simplest accumulator of mechanic energy - a rubber. Rubber will stretch on falling, and compress on rising, helping servo to open the cap.
Step 9: Power Up!
You can power this system by dc power supply. All electronics I fix by cable tie and cover by not transparent tape. Also, you can build all mechanism outside the trashcan, but I wanted to make robo trashcan that is ordinary outside, just a sensor is showed up.
Step 10: The End.
There is a problem with power, because arduino consumes 20 mAms. It is so much. 5 ah powerbank can power this trashcan only for a week. So it is good idea to use attiny13 or another MK instead of arduino.
So, it is robo trashcan, that is opening its cap when you pass your hand above it.