Master Thesis - Hochschule Bonn-Rhein-Sieg

2. Overview on human-robot Master Thesis Björn Ostermann page 12 of 126
In recent years the primary focus in the field of safe industrial robot collaboration was on the force
sensors, which detect only collisions, and on camera based solutions. In 2005 [17] Lu and Chung
presented a wrist force/torque sensors using robot, equipped with a weighted path planning algorithm.
The DLR lightweight robot [16] presented in 2007 allows torque sensing in its joints, which makes
fast collision based planning possible.
In 2007 F. Som, Manager Control Development Software – REIS Robotics, presented an approach
with a 3D camera mounted to the ceiling that observes the roboter’s working environment [56]. Little
information was given on the used hardware and algorithms, as well as on the state of the project, but
individual communication with Mr. Som showed that the hardware set-up of the approach from REIS
is similar to the set-up of the approach developed in this master thesis. Differences exists in the
handling of the acquired image data. For example REIS is trying to eliminate the robot for further
calculations by knowledge of its position, while this master thesis identifies the robot but keeps it in
the acquired data because of safety reasons.
Among other problems, camera based solutions suffer from occlusions of objects by other objects in
the workplace. This is a problem independent from the chosen approach, whether 2D data or 3D data
is acquired from the sensor system. Thus in recent years the number of studies on combining several
data sources has increased. In 2008 Elshafie and Bone [14], Mure and Hugli [24] and Lenz et al. [25]
presented solutions to this problem. Also the number of systems that try to anticipate human
behaviour, as shown by Lenz et al. [25], is increasing.
Another approach to the problem that has come up is equipping the human with sensors, rather than
the robot. This was shown by Meisner et al. [5] in 2007, as described above, and also by Tamei et al.
[26] who used a surface electromyogram in 2008 to simulate force sensors on the robot from the data
collected at the human body.
2.2.1 Morpha
From 1999 to 2003 the research project MORPHA was conducted [50]. The goal of this project was
the interaction, communication and collaboration between humans and intelligent robot assistants. In
the course of the project, several approaches on the given topic were presented.
As one of the first results on industrial robot arms from this project Wösch and Neubauer showed in
2001 an eight degree of freedom robot with a stereo camera system, a laser scanner and a tactile sensor
skin that could evade humans [8]. They used real forces, measured by the tactile skin, as well as
virtual forces, induced from the model of the environment, to move the robot arm away from objects.
In the MORPA project "rob@work" in 2002, Helms, Schraft and Hägele used a camera mounted at the
ceiling and a 3D laser scanner behind the working place, to achieve a collaborative workplace of a
human and an industrial robot arm [9]. The robot arm was mounted on a mobile platform and could
thus be transported to other workplaces, while the camera and 3D laser scanner were stationary.