# A Detailed Look into SEA\(Serial Elastic Actuator\)

## why we need to know this

SEA is a commonly used actuator. It is powerful, a lot of research and product are based on SEA. For example, the Rethink Robotcs widely use SEA in their colaborate robot, Hebi Robotics use SEA in their modules as well.

 ![](https://spectrum.ieee.org/image/MjYxMjM2MQ.jpeg)  
 Rethink Sawyer Robot, All the joints are SEA

 ![](http://docs.hebi.us//resources/quickstart/two_actuators.jpg)  
 Hebi Modules

More importantly, I am recently dealing with SEA motors from HEBI robotics. I have got a new [Daisy Robot](http://docs.hebi.us/resources/kits/assyInstructions/X-Series_Hexapod.pdf). The Robot is heavy and it trembles a lot while walking. So I want to make it crystal clear that I understand the motor in the very basic level.

This also help understanding the famous branch of actuator.

## What is SEA

SEA is a mechanical mechanism. It could add to any kind of actuators if properly designed. To put it simple, it attach a spring bwtween the end shaft of the motor, to create elasticity and reduce stiffness of the motor.

## A little bit of history

The famous [paper from Gill Pratt MIT](http://www.cs.cmu.edu/~cga/legs/jh1c.pdf).

## How does this work and Why this works

## Pros & Cons