With some friends, we had the idea to use a real slingshot to play Angry Birds instead of using a standard mouse! The objective is to plug the slingshot into a computer over USB and to kill pigs with it!
The problem is that we had to find a microcontroller or a little board with a USB controller and a USB library already developed. Quite recently, Mbed has published a USB device library which is able to emulate a bunch of peripherals.
Combining the two previous ideas, we decided to design a real slingshot using an Mbed connected to a computer over USB to play Angry Birds!
Take a look at the video!
With a real slingshot, you tilt the slingshot and stretch sling. The idea to measure these was using:
- An accelerometer - this can measure the tilt by tracking the gravity vector (which way is down!)
- A rubber stretch sensor - this can be used as the sling, and measure how much it is stretched
The slingshot was crafted by Chris Jarratt, from a branch found in Epping Forest, London! This is the structure in to which I embedded all the electronics.
Step 1: What do you need to realize your own Mbed slingshot ?
- A piece of wood in order to build the slingshot. I advice you to know a good carpenter ;) Take a look at Chris website
- Then you need some sensors to detect angle and strength:
- 3-axis accelerometer for the angle: ADXL345. You can easily read accelerometer data as an mbed library is available to use it
- A stretch sensor for the strength. We use this flexible cord which the resistance changes when stretched. To use this sensor, you also need a 10k resistor in order to read a voltage in a voltage divider circuit
- Two pin header sockets to plug the mbed
- A USB type B connector
- A USB cable A to B to connect the mbed to a computer
- A solder iron
- A breadboard
- A veroboard