Professor Junho Oh started working on humanoid robotics in 2000 at the Machine Control Lab (MCLab) at KAIST in South Korea. The lab eventually became known as the HUBO lab, short for humanoid robot. In 2011, Professor Junho Oh and Dr. Jungho Lee founded Rainbow Co. which is now known as Rainbow Robotics. Some biped research is still done at KAIST after Professor Junho Oh’s retirement; he decided to go full time at Rainbow Robotics after winning the DARPA Robotics Challenge.

KHR-1

KHR-1 is a 119 CM tall humanoid with a weight of 48 kg. It features 6 DoF per leg, 4 DoF per arm, and 2 DoF in the waist for a total of 22 DoF. Every joint uses a harmonic drive reducer. Joints where the harmonic drive couldn’t fit in line, such as the knee, use a belt between the output of the motor and input of the harmonic. For intersecting joints, such as the elbow, a bevel gear is used between the output of the motor and input of the harmonic. KHR-1 draws less than 100 watts in standby and around 200 watts while walking.

Note: Some sources name KHR-1 without the arms as KHR-0

More info in Development of a Humanoid Biped Walking Robot Platform KHR-1 - Initial Design and Its Performance Evaluation

KHR-2

Improved joint stiffness and appearance compared to KHR-1. KHR-2 is 120 cm tall with a weight of 54 kg. The maximum walking speed is 1 km/h. KHR-2 can operate on battery power for a maximum of 50 minutes. KHR-2 has a total of 41 DoF: 6 DoF per leg, 6 DoF per arm, 5 DoF per hand, 1 DoF in the waist, 2 DoF in the neck, and 2 DoF per camera. A single board computer (PCM-9575) with a Pentium III acts as the main controller. This computer runs Windows XP and the main control program is written using Visual C++.

More info in System Design and Dynamic Walking of Humanoid Robot KHR-2

KHR-3 Hubo

KHR-3 is 125 cm tall with a weight of 55 kg. The mechanical stiffness of links, the gear reduction, and the exterior shell have been improved compared to KHR-2. The max walking speed of KHR-3 is 1.25 km/h. The robot uses 24V brushed DC motors for all joints. KHR-3 has a total of 41 DoF: 6 DoF per leg, 6 DoF per arm, 5 DoF per hand, 1 DoF in the waist, 2 DoF in the neck, and 2 DoF per camera. KHR-3 is the first in the series to feature the sphere-like cover over the hip joints. The main computer uses a Pentium III along with a CAN bus card for talking to the motor controllers.

More info in Mechanical Design of Humanoid Robot Platform KHR-3

HUBO FX-1

FX-1 is a biped robot capable of carrying a human payload of 100 kg. FX-1 is 199 cm tall and 150 kg including the cockpit. The hip roll and knee joints use 800 watt AC motors paired with 100:1 harmonic reductions with a max torque of 212 NM. FX-1 uses the same single board computer and OS as KHR-3. Structural vibrations, caused by reducing the mass of the aluminum frame, caused instability in walking. This is solved by using a mass-spring model, a compensator, and sensory feedback. The max walking speed is 1.25 km/h. FX-1 operates on external AC power.

More info in Experimental Realization of Dynamic Walking for a Human-Riding Biped Robot, HUBO FX-1

Albert HUBO

Albert HUBO is a modified KHR-3 with an animatronic head of Albert Einstein. The face itself, designed by Hanson Robotics, has 28 DoF.

More info in Design of Android type Humanoid Robot Albert HUBO

KHR-4 HUBO 2

HUBO 2 (also referred to as KHR-4) is a 125 cm tall humanoid with a weight of 45 kg. The maximum running speed is 3.6 km/h. HUBO 2 features two computers powered by Pentium III CPUs: the head computer (PCM-3372) and the body computer (PCM-3370). The body computer runs Windows XP service pack 2 with Real Time Extensions 6.5 by Ardence. Maxon brushless DC motors are used for the joints versus brushed motors in the original HUBO.

The commercial version of HUBO 2 (referred to as HUBO2+) was sold to: University of Electronic Science and Technology of China, Institute for Infocomm Research in Singapore, Drexel University (bought 7!), and Google.

DRC-HUBO

DRC-HUBO-1 is 155 cm tall with a weight of 60 kg. The arm and leg length were increased compared to HUBO 2. Forced air is used to cool the motors. Except for the arm joints, all other joint modules are reused from HUBO 2.

DRC-HUBO+

DRC-HUBO+ is 170 cm tall with a weight of 80 kg. The robot is capable of rotating the torso so that the knees face backwards, and able to lay down and locomote using wheels. The robot has a total of 32 DoF: 7 DoF per arm, 6 DoF per leg, 1 DoF per hand, 2 DoF for wheels, 1 DoF in the head, and 1 DoF in the waist. The robot has a max walking speed of 1.8 km/h and a max wheel mode speed of 3.5 km/h. The payload of each arm is 10 kg. The two batteries allow for an operation of up to 4 hours. The external wires are now routed through hollow shafts in each joint. DRC-HUBO+ has two cameras (Grey Flea3-GigE) and one LIDAR (UTM-30LX-EW).

DRC-HUBO+ was used by team KAIST to win the DRC finals. Team UNLV also used DRCHUBO+ and came in 8th place.

Note: NRL version? Recent photos and videos from Rainbow Robotics show Intel realsense cameras and Velodyne Puck lidar mounted on the head of DRC-HUBO+

More info in Development of the Humanoid Disaster Response Platform DRC-HUBO+

HUBO FX-2

FX-2 is an updated version of FX-1 made to carry the torch for the 2018 Pyeongchang Winter Olympics. FX-2 is 220 cm tall and weighs 260 kg. The robot has arms and hands controlled by the rider.

Gazelle

Gazelle is a biped walking robot platform based on DRC-HUBO+. It is 130 cm tall with a weight of 37 kg. The two toe actuators are actuated remotely from higher up on the leg (this is done to reduce leg inertia). The robot also features a new stacked fin motor cooling system, separated hip roll and pitch actuators for improved range of motion, and a linked knee joint. The torso can be rotated around, so the biped can walk with human-like knees or backwards facing knees. The maximum walking speed is 1.8 km/h. An upgraded version called Gazelle2 is being worked on.

More in in Design and control of the rapid legged platform GAZELLE

CYBO

CYBO is a 12-DoF biped powered by 11:1 cycloidal geared servos. The low gear ratio and low friction provide good efficiency and backdrivability. The initial prototype shown above had issues with stiffness and torque bandwidth. The next version of CYBO was tested successfully in June 2021. The video of it successfully walking was made private (most likely as it was for a soon to be published paper), however, the author left up a great video of an earlier test.

Hydraulic Humanoid

Not much published information yet. Hydraulic biped developed in the DRCD (Dynamic Robot Control and Design) lab at KAIST. Features on board hydraulic power unit and custom hydraulic linear actuators.