Intro to Robotics

Homework # 1

Below are few pictures of a robot that I will discuss about in terms of sensing, planning, and acting. This robot is called "BigDog".

BigDog is a rough terrain robot that can walk, run, climb, and carry heavy loads, as seen above. It has 4 jointed legs similar to the legs of animals, and is approximately size of a small dog.

 

Sensor

BigDog has a control system that handles varieties of sensors that keeps the robot maintain its lateral balance and posture and regulate energy. Some of these sensors keep track of leg kinematics, ground contact, lateral velocity, etc. This allows BigDog to travel anywhere people and animals can, such as icy fields, mountains, rubbles, rocky roads, and so on. It has LIDAR and a stereo vision system so that it can track a leader (human wearing a control vest), and calculate obstacles. BigDog also has other sensors that focus on the internal state of the robot, such as hydraulic pressure, engine temperature, battery energy, and so on.

Plan

BigDog uses its sensors for mapping by calculating obstacles and slopes of its path, and estimating its current pose. It can also use the history of leg kinematics to estimate ground planes, and adjust positions such that its legs don't overlap and collide. When the robot is given some lateral velocity (falling, kicked), it predicts the velocity and acceleration of necessary leg placement to regain balance.

Act

The sensors that tracks joint pressure, ground contact and such will allow BigDog to act accordingly to maintain body posture and ground contact, by controlling force, leg positions and the body's lateral velocity. When BigBot detects lateral velocity, induced from falling, slipping or simply being kicked to the side, the robot will swing its legs and place its feet according to its prediction to prevent loss of balance, and ultimately falling. When BigDog is put into obstacles such as pile of rocks, ice field, or steep hills, BigDog controls its legs and movement similar to those of an actual animal.