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The Smalldog Project at DFRobot

Introduction: The Famous Big Dog from Boston dynamic BigDog is a dynamically stable quadruped robot created in 2005 by Boston Dynam-ics with Foster-Miller, the NASA Jet Propulsion Laboratory, and the Harvard University Concord Field Station. BigDog is 3 feet (0.91 m) long, stands 2.5 feet (0.76 m) tall, and weighs 240 pounds (110 kg), about the size of a small mule. It is capable of traversing difficult terrain, running at 4 miles per hour (6.4 km/h), carrying 340 pounds (150 kg), and climbing a 35 degree incline. Locomotion is controlled by an onboard computer that receives input from the robot's various sensors. Navigation and balance are also managed by the control system. (From Wiki).

Littledog from Boston Dynamics As for research purpose, Boston Dynamics develop a small version of the Big Dog, which is named as LittleDog. LittleDog has four legs, each powered by three electric motors. The legs have a large range of motion. The robot is strong enough for climbing and dynamic locomotion gaits. The onboard PC-level computer does sensing, actuator control and communications.

Some quadruped robot developed by other companies or institutions

SmallDog from DFRobot The SmallDog developed by DFRobot composed of a main platform, serves as body, and four legs, each powered by three servos. The servo we choose here is CDS 55XX, produced by Up-tech. As for the on-board micro-controller, we use the powerful DFRduino Mega board with an expansion shield, which could realize the control of different gaits and behaviors of the robot. A wireless programmer module is also added to the robot, so that we could realize remote control of the robot through a joypad. For the Version 1, our smalldog just like a baby dog who could take some simple actions that move forward, step backward, turning, squat down, lie down and so on. It also has a system of variable speed. That is to say it can walk very slow like a worm or move fast vigorously.

How to assemble a Small Dog 1. Assemble the servos with bracket First choose the appropriate servo disk and put it on servo.

   Then put the servo into the servo-bracket. Please pay attention to the installation direction of them.

All of the 12 servos should be assembled in the same way. At the same time, we must put two separate servo brackets together to make the leg of the dog.

Next, put in the servos in the brackets. Also, here we must pay close attention to the installation direction.

As we have made the legs, we should think about how to fix them to the body. We use the following two pieces,

and assemble them in the way as:

   Then put in the servo, as the hip of the dog.

As for the foot, we choose certain part to simulate real dog’s foot. While assembling, we should still pay attention to the direction.

Then put it on the leg. Here we the long orange joint lock to stabilize the connections.

After fixing them with the hip part, then an intact finishes.

And in order to communicate with the micro ship, some cables are essential. From the user manual of the servos CDS55XX, we get the typical connection diagram as follows:

So considering we only use three servos for each leg, we need three cables.

Assemble other three legs in the same way. Then what left is an easy task, to make a body for our dog. Here we use two big carriages, connected by some interconnecting piece.

Assemble the four legs on the four angels of the body, then the small dog come into being.