Legged robots with arms can potentially replace humans in dangerous and dirty tasks, where vehicles with wheels and tracks cannot go. Some possible application domains are: disaster recovery (such as cleaning-up the Fukushima nuclear power plant), search and rescue, forestry and construction. Traditionally quadrupeds have been limited to load carrying or observation tasks as they have no manipulation ability. To remove this limitation, arms can be added to the body of the robot, enabling manipulation and providing assistance to the robot during body stabilization. The arm system will add a new dexterous manipulation capability to the already wide range of abilities of the HyQ robot, e.g., trotting, running, jumping, stabilization, external disturbance rejection, quick reflex action, and careful foot hold planning during navigation through unstructured terrain. This enables HyQ to perform new tasks, including: removing obstacles, grasping and manipulating objects, opening doors, or assisting the robot's balance.


For more details on HyQCentaur you can read our  CLAWAR  conference paper (see reference below)   and a recent    Reuters   article of January 2016.

You can see a video of HyQCentaur here: 

Conceptual design of HyQCentaur:

The DLS lab within ADVR has been working on the development of centaur robots for some time now. A conceptual design of the HyQ robot with two arms mounted on the torso was initially publicized on the IEEE Spectrum website in 2012.


HyQCentaur concept1 reduced
Hyq valve pipe

Conceptual tasks performed by the centaur robot: opening a door, carrying an object(left)
passing through a narrow passage, stabilization of the robot body (right)

Since its humble beginnings it has matured in to a fully functional design. Below you can see a CAD rendering of both the Left and Right versions of the arm mounting on the HyQ robot.


CAD model of HyQCentaur with the recently designed and tested Hydraulically Actuated Arm(s) (April 2015): (left) in stowed position and (right) during operation.


The Hydraulically Actuated Arm:

We are proud to presents a compact and light-weight hydraulic robotic arm that is full torque controlled and without an external control unit. Perfectly suitable to be mounted on quadruped robots which are meant to perform sophisticated dynamic tasks. The designed arm is equipped with position encoder, torque and force sensors to achieve torque control. The video presents preliminary experimental results, demonstrating torque controlled capability to change joint impedance and user and robot interaction while performing a continuous motion with different speeds.


(Rehman, 2015)

System Overview

The following table lists the key specifications of the robotic arm.

Specification Value Joint Total range-of-motion Torque
Arm extension 0.743m Shoulder Adduction/Abduction  (SAA) -3.14/0.52 [rad] 126[Nm]
Weight 12.5kg Shoulder Flexion/Extension (SFE) -0.74/0.83 [rad] 120[Nm]
Maximum payload (fully extended) 10kg Humerus Rotation (HR) -1.57/0.068 [rad] 120[Nm]
Actuation system Hydraulic Elbow Flexion /Extension (EFE) 0/2.21 [rad] 225[Nm]
Control mode Torque controlled Wrist Rotation (WR) -2.01/1.57 [rad] 60[Nm]
Degrees of freedom 6Dof (3+1+2) Wrist Flexion/Extension (WFE) -1.57/0.52 [rad] 100[Nm]