Atlas HD (hydraulic Atlas)

What Atlas HD was

Atlas is Boston Dynamics' humanoid robot. In 2016 the company unveiled a next-generation Atlas^[1]. IEEE Spectrum's ROBOTS database calls this generation Atlas HD, or hydraulic Atlas^[1]. Compared with earlier models, the 2016 Atlas was smaller, lighter and more agile^[1].

Hardware and specifications

The database lists the 2016 Atlas at 150 cm tall and 80 kg, with a speed of 5.4 km/h and 28 degrees of freedom^[1]. Degrees of freedom are the independent directions in which a robot's joints can move; the more of them a machine has, the more postures it can take and the more varied the movements it can attempt.

For sensing, the listed hardware includes LIDAR and stereo vision^[1]. LIDAR sends out laser light and times the reflections to measure how far away surfaces are; stereo vision compares two viewpoints to judge depth. Both are ways of letting a walking robot know where it is and where the obstacles are.

The machine carried three on-board computers and a custom battery, and used 3D-printed titanium and aluminium parts^[1]. Printing metal parts makes it possible to build stiff, load-bearing shapes that would be awkward to produce by conventional means.

It was designed to operate both outdoors and inside buildings^[1]. That is a demanding combination: outdoor ground is uneven and the light keeps changing, while indoor space is tighter and more cluttered.

How it was powered

The 2016 Atlas was electrically powered and hydraulically actuated^[1]. In practice that means electricity supplies the energy, pumps pressurise a fluid, and that fluid drives the joints. Hydraulics give high force and fast response, which suits lifting; the cost is complexity, since the machine needs more plumbing and more parts that can fail.

What it demonstrated

Boston Dynamics' innovation timeline credits the hydraulic Atlas with parkour and dance, with whole-body control algorithms, and with manipulation of heavy and irregular objects^[2]. Whole-body control means solving for arms, torso and legs together rather than steadying the robot first and reaching afterwards: the machine keeps its balance while it acts. Parkour and dance are singled out because they demand that the robot stay upright through fast, continuous and large changes of posture.

On manipulation, Boston Dynamics said the hydraulic Atlas could already lift and manoeuvre a wide variety of heavy, irregular objects^[3]. Irregular objects are harder than tidy boxes, because the grasping points are unclear and the centre of mass is difficult to predict.

Retirement

The ROBOTS database describes this version as the most agile humanoid in existence until it retired in 2024^[1]. In April 2024 Boston Dynamics announced the retirement of the hydraulic Atlas^[3][4].

Seen in sequence, the 2016 machine marks a stage at which a hydraulically driven humanoid could move through parkour courses, dance and carry heavy loads. The movements it showed became a reference point for what people expected a humanoid robot to be able to do, and the 2024 announcement closed the book on this generation.