IEEE Robotics & Automation Magazine - September 2018 - 43

needs. For example, the hand was deliberately not designed
for heavy manipulation but only to be good enough for
expressive interaction. The "Hardware Design Outline" section provides information on the hardware and sensors.
Interactivity
Interaction is one of the key features of the Pepper robot's
capabilities. The need for natural and intuitive interaction is at
the heart of these, but the machine's design also considers the
real-life situations in which one means of communication
might not always be particularly reliable or useful. Hence,
Pepper has a multimodality of interaction interfaces. This
includes a touch screen, speech, tactile head and hands, and
light-emitting diodes (LEDs).
Several software components were developed to facilitate the necessary perception abilities and ensure a smooth
HRI, including the capacity to recognize and respond to
human emotions, a library of expressive gestures, and
microlevel behaviors for displaying liveliness. To achieve
human-like and graceful expressivity through body language, the kinematic structure of the robot was carefully
designed with 17 joints. The three omnidirectional wheels
help in achieving smooth movement and support the realization of local, small displacements in more natural ways.
The "Degrees of Freedom and Actuators" section provides
information on the design kinematics, and the section
"Multimodality of Natural Interaction at the Core" discusses the interaction multimodality.
Autonomy
Long-term autonomy is another important requirement, so
the robot can serve for an entire workday in SoftBank stores
without recharging or intervention. Therefore, the whole system was designed to balance the software and hardware loads
and achieve a battery life of up to 12 h. In addition, a specifically designed docking station for autonomous charging was
developed. Furthermore, there are modules and apps for the
robot to achieve behavioral autonomy in particular applications, reducing the need for human intervention. The sections
"Support for Behavioral Autonomy" and "Basic Navigation
and Manipulation Capabilities" provide pointers on the
autonomy aspects.

These are software controlled to change colors and intensity.
The machine has an Atom E3845 processor with a quad-core
central processing unit (CPU) and a clock speed of 1.91 GHz.
It has a 4-GB double-data-rate, type-three random-access
memory and a flash memory of 32 GB embedded multimedia card, of which 24 GB are available for users.
Degrees of Freedom and Actuators
As illustrated in Figure 2, the Pepper robot has 20 degrees of
freedom (DoF) for motion in the whole body (17 joints) and
omnidirectional navigation (three wheels). The DoFs include
two in the head, two in each shoulder (left and right), two in
each elbow (left and right),
one in each wrist (left and
right), one in each hand
Our observations suggest
(five-fingered left and right
hands), two in the hips,
that, for NAO, people
one in the knee, and three
in the base. The omnidigenerally call it him, but for
rectional wheels allow the
robot to climb a 1.5-cm
Pepper, people address it
step and up to a 5° slope.
The actuators were
as him, her, or it in almost
de signed by SoftBank
Robotics based on brush
equal measure.
dc motors in the upper
limbs and a brushless dc
motor in the lower limb. The joint-position sensor is magnetic rotary encoder-based, and there is a 12-b position sensor on each motor for the upper limbs. In almost all actuators
(shoulder, elbow, neck, and leg), plastic bushings are used to
ensure good guidance. They are lighter, smaller, and cheaper
than ball bearings. With plastic bushings, there is a bit more
friction, but it is below the acceptance threshold of the design
needs for these joints. Ball bearings are used only for the
wheel actuators.

Head Yaw
Head Pitch

Hardware Design Outline
The following specifications are based on Pepper version 1.8a.

Shoulder Pitch

Body and Computer
The robot's hull is constructed of high-quality plastic, and
many parts consist of soft plastics to reduce the risk of pinching during physical interaction and minimize damage if the
machine should fall over. There are no external sharp edges.
Tactile body parts composed of capacitive sensors indicate
when the robot is touched.
Pepper has a height of 1,210 mm, a width of 480 mm, and
a depth of 425 mm. Its weight is 28 kg. The robot is equipped
with several LEDs to signal and support communication.

Elbow Yaw
Elbow Roll

Hip Roll

Wrist Yaw

Hip Pitch

Shoulder Roll

Knee Pitch

Hand

Back Wheel
Front Right
Wheel
Front Left
Wheel
Figure 2. The Pepper robot's joints.

september 2018

IEEE ROBOTICS & AUTOMATION MAGAZINE

IEEE Robotics & Automation Magazine - September 2018

Table of Contents for the Digital Edition of IEEE Robotics & Automation Magazine - September 2018