IEEE Robotics & Automation Magazine - December 2019 - 63

Full-Body Telepresence Suit
The main part of the full-body telepresence suit is the
upper-body exoskeleton with arm exoskeletons covering
shoulders and elbows, two spherical wrist exoskeletons,
and two hand exoskeletons (Figure 2). Hence, complex
operator arm, wrist, and hand motions can be intuitively
transferred to the robot. While the arm motions can be
also realized through off-the-shelf lightweight manipulators, the exoskeleton, designed to maximize performance
in human-robot interaction, features high transparency, a
large workspace, and high maximum payload/rendered
force. In contrast to similar teleoperation systems [15], the
presented exoskeleton considers force feedback of both the
arm and the hand-palm. The arm exoskeletons cover
about 90% of the natural workspace of the human upper
arms without singularities. To keep the number of moving
masses low, the device is driven by electric actuators
remotely located behind the operator seat and connected
to the joints through idle pulleys and in-tension metallic
tendons. Force feedback is provided for each individual
joint. Two rotational 3-DoF forearm-wrist exoskeletons
track operator wrist motions and provide independent
torque feedback for each axis [16]. In developing these
components, researchers focused on making the exoskeleton comfortable for the person wearing it and maintaining
an open structure to avoid collisions between parts during
bimanual operational tasks. The 6D end-effector poses of
the two arms are computed and sent to the Centauro
robot, which uses them as references to compute joint values through IK. Two hand exoskeleton modules track
operator finger motions and provide grasping-force feedback [17]. Figure 3 shows the overall architecture of the
telepresence suit. The control incorporates friction and
gravity compensation as well as the time-domain passivity
approach combined with a position-force scheme to
achieve high transparency [18].

Since Centauro's quadrupedal lower body is considerably
different from the bipedal lower body of humans, direct control of all four legs through an exoskeleton is not feasible.
Instead, we decided to use pedals to control omnidirectional
driving, while more challenging locomotion is controlled by
the support operators. In addition, the operator wears an
HMD for immersive 3D visualizations.
Support Operator Interfaces
While the telepresence suit is especially useful for tasks
requiring challenging manipulation, several other tasks can
be managed without the suit and with an increasing level of
autonomy-requiring less input from the operator. Omnidirectional driving can be controlled through a joystick. A
6D mouse provides Cartesian control of 6D end-effector
poses for arms and legs. For more complex motions, a keyframe editor enables configuration control and motion generation in joint space and in Cartesian end-effector space.

Master
Left-Hand Exoskeleton
Left-Arm and -Wrist
Exoskeletons
Open-Loop Torque Control
With Friction and Gravity
Compensation
Right-Arm and -Wrist
Exoskeletons
Open-Loop Torque Control
With Friction and Gravity
Compensation
Right-Hand Exoskeleton

Figure 2. The telepresence suit allows the operator to intuitively
control the remote Centauro robot in bimanual manipulation
tasks while providing force feedback. The support operator
station can be seen in the background.

Slave
4-DoF Force
4-DoF Position
6-DoF EE Force
6-DoF
EE Position

6-DoF EE Force
6-DoF
EE Position
5-DoF Force
7-DoF Position

HERI II Hand
Centauro Left-Arm
Closed-Loop Position Control
With IK

Centauro Right-Arm
Closed-Loop Position Control
With IK
Schunk Hand

Figure 3. An illustration showing the multilateral position-force teleoperation architecture. While hand positions are perceived on joint
level and hand forces are measured for each finger, arm positions and forces are projected to the end effectors (EEs).

DECEMBER 2019

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IEEE ROBOTICS & AUTOMATION MAGAZINE

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IEEE Robotics & Automation Magazine - December 2019

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