This robot is known as BigDog. Developed by Boston Dynamics and other big names in the robotics field, BigDog is a robot developped for military applications. It's a quadruped robot that is dynamically stable, allowing it to travel through difficult terrain. Its primary application was to serve as a robotic pack mule, carrying supplies for soldiers.
In terms of Sense-Plan-Act, BigDog uses a variety of sensors to measure information such as velocity and acceleration, temperature, and altitude. With this information gathered, BigDog is able to plan its position in order to maintain stability. Finally it moves its legs to that position.