Yujin
Wakita, Shigeoki Hirai, Takashi Suehiro, Toshio Hori
Autonomous
Robots, N0.10, 2001
Summary
The authors
introduce the concept of safety based on intelligent augmentation of robotic
systems. In previous studies the authors introduced the concept of tele-robotic systems (1992,1995,1996),
where a robot is operated from another position with no physical contact and
monitored through a television, and intelligent
monitoring (1992), a system
allowing conveyance of only required information through selection of data. The
expansion of this last system has been the snapshot
function (1995), where a laser pointer helps in teaching mode to estimate
the deviation of the position, while the operator can move the robot, teaching
the estimated relative deviation. A further implementation is the here proposed
projection function (2001), where a
robot and human jointly operate through a Digital Desk, a special environment
provided with a projector perpendicular to the working table and a speaker. The
aim of this research is to achieve intelligent augmentation in order to prevent
and avoid undesirable contact, information sharing is a fundamental aspect in
cooperative tasks between a person and a robot (Wakita, 1998). The experiment
test a human and robot operating in mainly 5 states (initial, approach, grasp,
release and final), the main issue is this kind of problem to be solves are:
the person does not know the delivery coordinate, the person must keep holding
the object until it is released, the person might be frightened by the robot
movement.
The projection function consists of projecting on the table the
simulated images of the moving robot, so that the human operator knows in real
time the robots trajectory and understand the delivery trajectory. Force
sensors in the robot’s fingers are used in order to allow the robot understand
when the object has been grasped by the operator. A new teaching method also is
introduced: the operator activated the teaching mode by touching the robot’s
hand, then, instead of physically moving the manipulator, the projected image
of the robot follows the operator’s hand to destination, the advantage is that
only the model is required and no robot movement; the robot confirm through the
speakers that the teaching trajectory has been saved.
The force sensors are an efficient communication method only during grasping,
visual monitoring appears to be necessary for the entire delivery task.
It can be observed that humans in cooperation require visual feedback in
order to understand that their motion and activity has been understood, each
person expects to be observed during their action. So visual information
appears to be extremely important by means of perception and it enhance safety
in the system.
The digital desks comes to help once again in monitoring and indicating
robots and humans in the system, in fact while operating a symbol (in the
experiment it is a white rectangle) is projected on the hand of the operator
when the robot has detected an action, in this way the human is aware that the
robot knows about its presence.
In order to perform the experiment, a CCD camera was used for detection
of human’s hand and robot position, and a video projector (SANYO LP-SG60)
mounted on the ceiling in parallel with the camera.
The system as programmed, projects a white rectangle on the human’s hand
when the CCD and the computer had performed the detection, while stationary
hand is recognized a the delivery position.
Key Concepts
Human-Robot Interaction, Human-Robot Cooperation, Team Working
Key Results
The experiment appears to be
useful prompting the importance of communication between robots and humans
working together, a communication which need also visual feedback in order to
ensure safety. A big part of communication is in fact performed not only by
direct communication, but also by indirect feedback, showing that the message
has been properly received. Future research may require adding information to
the system.
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