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FIGURE 8. The Hitec
HSR 8498HB
robot servo.
FIGURE 7. The
Robonova with
its servos
disconnected.
problem when many servos in a row
needed to be controlled from a single
control source.
The special HSR-8498HB robot
servo shown in Figure 8 was custom
designed for the Robonova 1. It is
different from standard servos in
several ways. Besides having 103 oz-in
of torque, these servos can be used in
a standard configuration with a single
horn attachment, or can utilize the
second custom idler wheel to create
sturdy robot joints that don’t wobble.
The idler wheel is mounted on the
opposite side of the servo from the
horn and at the same axis, so it is
perfect for solid leg and arm robot
joints. The use of what Hitec calls
“Karbonite” gears in the servo’s
geartrain allow for minimal gear
76 SERVO 01.2013
FIGURE 9. Samsung Roboray
humanoid robot.
backlash in the servo’s output — a
very important factor in the leg servos
of a bipedal robot.
Korean Companies
Develop a New
Servo Concept
Korea has long amazed us with
so many innovative robotic products
and companies. The Hubo robot and
the very inventive KAIST Institute have
been some of the most popular
Internet robot/robotics searches for
several years. Samsung’s new torque-controlled humanoid robot Roboray
(seen in Figure 9) — recently unveiled
at IROS 2012 in Portugal — illustrated
just how sincere Korea is in advanced
robotics development.
Roboray was developed as a test
platform to study bipedal locomotion
using torque-controlled joints. The
robot is a bit smaller than an average
human at four feet, 11 inches tall; it
weighs 136 pounds. It has 32 degrees
of freedom, not including its fingers.
The research team will soon apply
speech and facial recognition to the
robot to allow it to work with
humans.
The unique parts of Roboray are
the knee, hip, and ankle joints. They
utilize torque-controlled harmonic
drive actuators and compliant tendon-driven actuators that give the robot
relaxed, human-like movements. These
joints can be tightened or loosened
according to load and movement, to
allow the robot to walk more
efficiently upright with straight knees.
Previous humanoids such as the
Honda Asimo must use a non-human
bent knee walking posture.
The Robotis
Dynamixel Allows
for Some Unique
Bipedal Robots
Robotis was established in South
Korea in 1999, and developed its first
humanoid bipedal robot in 2003. In
July 2005, Robotis introduced the AX-
12 Dynamixel actuator and the Bioloid
robot kit. The OLLO robot
construction kit for children came in
2008, followed by the Bioloid
Premium kit in 2009 — the same year
they opened their US office in
southern California. It is their
Dynamixel line of rotary actuators that
set the company apart from other
servo manufacturers. The Bioloid
