Mechanism and Structures: Humanoids and Quadrupeds - Bioinspired Approaches for Human-Centric Technologies - page 150

Fig. 5.16 (a) Hydraulic components for external power, (b) Full onboard hydraulic system
5.4.2.6 Mechanical Structure
Figure 5.13 shows the mechanical structure of HyQ. All mechanical parts are
fabricated either in Ergal , a strong aluminium alloy (type 7075), or in stainless
steel (39NiCrMo3) for the heavily stressed parts. The torso is formed from folded
Ergal sheet (thickness 3 mm) with internal ribbing to increase torsional robustness.
This design is simple, rigid, (comparatively) light-weight, easy to manufacture and
leaves space to mount and accommodate secondary components.
5.4.2.7 Hydraulic System
The hydraulic system consists of a pump powered by an 8-9 kW ac electric motor
(stage 2), oil 0.5 L tank, heat exchanger, accumulator, filter, central manifold with
relief and vent valve, 12 MOOG E024 valves, pressure sensors, 8 hydraulic cylin-
ders (Hoerbiger LB6-1610), 4 rotary hydraulic motors (Hydro-hips), fittings and
tubing/hosing. Figure 5.16 shows the hydraulic system as mounted within the
robot torso.
5.4.2.8 Sensory System
The robot is equipped with a network of over 50 sensors for low- and high-level
control, system state monitoring and diagnostics, comprising the following: a
relative (high resolution) and an absolute encoder on each active joint, compres-
sion/tension load cells they are removed since the upgrade with the MOOG valves
for each hydraulic cylinder, IMU on robot torso and several sensors to measure the
state of the hydraulic system. For external perception some variants have stereo
vision (bumble bee), RGBD colour and depth sensor (Microsoft Kinect) and lidar
(Velodyne), together with custom-built force/torque sensing in the feet.