What is the ESA Grip experiment, and why does it require Alexander Gerst to be strapped into it?

Question

The text of this 14-June-2018 astronews.com tweet translated into English via google says:

IMAGE OF THE DAY: Today's picture of the day shows the German ESA astronaut Alexander Gerst working in the Columbus laboratory of the ISS.

What is going on here? He looks like he's strapped into some contraption with hoses and wires and headphones and a massive metal contraption in his lap.

Could this be an exercise device or a biophysics experiment of some type?

edit: the tweet links to this further explanation of the image: https://www.astronews.com/bilddestages/2018/20180614.shtml which when translated mentions:

He is currently working on the ESA Grip experiment , which aims to investigate the effects of gravity on the human nervous system.

...or possibly lack of gravity?

So I suppose the question is "What is the ESA Grip experiment, and why does it require Alexander Gerst to be strapped into it?"

Answer 1

It is biophysics, and specifically about our ability to grip things in microgravity:

The GRIP experiment studies the long-duration spaceflight effects on the abilities of human subjects to regulate grip force and upper limbs trajectories when manipulating objects during different kind of movements: oscillatory movements, rapid discrete movements and tapping gestures.

From Gerst's own blog:

How our brains learn this process is at the core of the Grip experiment, being performed in this image by ESA astronaut Alexander Gerst on the International Space Station on his current Horizons mission.

How does the experiment work? Alexander performs a series of movements while gripping a purpose-built sensor that measures grip-forces, moisture and acceleration, and more to assess how the body adapts to situations in which there is no up or down.

About the chair:

For experiment trials: the subject takes either a seated or supine position using the straps provided by the GRIP chair. The subject then performs a set of movements while holding the manipulandum. Three protocols are defined for the experiment trials: movement dynamics, reference frames, and collisions.