In this instructable you will learn how to transform your ordinary stuffed teddy bear into a not so lovable one. Only by using arduino basics you will achieve a creepy animated pal perfect for the spooky season !

We will be building a shiny red eyes animated teddy bear that rotates its head and moves its when you walk in front of it.

Step 1: List of Electronic Parts, Materials and Tools

Electronic Parts

Arduino Duemilanove Board
Breadboard
Arduino to usb cable
Ultrasonic Sensor
Two red leds
Two servo motors
Male to male solderless jumper cable wires

Materials

Medium sized stuffed teddy bear
Brown sewing thread
Red sewing thread
1.5 mm thick wood
Cardboard
Newspaper
White Glue
Paint

Tools

Scissors
Hot melt glue gun
Cutter or craft knife
Sewing needle
Paint-brush

Step 2: Schematic of the Electrical Connections

For a more optimal and summarized instructable here is a schematic of the electrical connections needed for this project.

Step 3: Flow Diagram

Step 4: Led Eyes Installation

For the led eyes installation it is necessary to previously separate the bear head from its body to ensure a more comfortable space of work. With the help of a cutter carefully cut the sewn threads that join the head with the body of the bear, it should come just right off.

Once the head has been detached from the body we can now proceed to extract both eyes following their circular perimeter with a cutter. Repeat this process until the eye itself feels loose, here, delicately remove the eye leaving a tiny little hole.

Before placing both leds it is important to previously weld a jumper cable with each leg, we recommend using distant colors to distinguish between the different poles.

Finally place each led with both cables inside the hole where the eyes used to be attached to, the led should be sticking out and the cables should be extracted from below. Assure the correct installation by connecting the cables to the arduino and breadboard (Check Step 2 for instructions) and turning both leds on.

To ensure the spookiness of the teddy bear, using red thread and the help of a needle, carefully sew the teddy bear's mouth drawing a X shaped path.

Step 5: Rotating Head

To allow the rotation of the head we will be using two 6 cm diameter wooden lids, used to seal and divide the head from the body.

On both lids we will be drilling two holes on both sides to allow the led cables to go through, by doing this, we are preventing the cables from getting tangled while the head rotates.

On the center of the bottom lid we will be also drilling two holes forming the shape of a servo head allowing it to attach permanently to the lid by using a hot melt glue gun. By doing this the servo will be stabilized so that the servo horn is spinning instead of the servo itself.

Pass the led cables through the top lid both little holes and glue it to the head using a hot melt glue gun. As for the bottom lid we are not going to permanently attach it to the body yet because there is still a lot of work to be done inside it.

Step 6: Rotating Arm

Using a cutter carefully cut the sewn threads that join the body to the teddy bear's arm, the arm should come right off.

Once the arm is detached from the body with the help of a hot melt glue gun we will be attaching a servo horn into the little arms hole, leaving the part that joins the servo to its horn sticking out of it. As for the servo itself we will be attaching it to the body hole where the arm used to and later on gluing it to the body's lid to stabilize its position.

Step 7: Ultrasonic Sensor

As the activation trigger for the system we are going to be using an ultrasonic sensor, which is activated when an object is put in front of it. We will be installing it in the teddy bear's belly, to make sure that the ultrasonic sensor is looking forward at all times the bear must remain seated.

The ultrasonic installation is fairly easy, with the help of some scissors we will be cutting two holes to attach both sensors, as seen on the pictures. Before that remember to connect each cable into each ultrasonic sensor port.

Step 8: Cardboard Knife

Step 9: Finising Details

As for the finishing details we are going to cut a little hole in the bottom back of the teddy bear. This is going to be used as an extracting point for all the cables of the electronic parts. Make sure to remember the origin of every cable so that it is connected to the suitable port, we recommend using color coding for that.

Once all the cables are extracted it is now time to glue the bottom lid to the body. Before that we are going glue the top part of the arms servo motor to the lid to ensure its stabilization. Now the only remaining thing to do is to connect all the different cables to the suitable arduino board and voilà, you now have an animated spooky teddy bear.

Step 10: Conclusion

This is a fairly easy to do arduino project which really makes the user feel that the teddy bear is totally alive. This project could be improved by building and installing a teddy bear skeleton inside the body, which would improve its durability and performance.