Schunk Robots Get MS Sufferer Back to Work

Lena Kredel suffers from multiple sclerosis. She cannot move her arms and legs, but nevertheless she is working. The literary scholar originates from Bad Segeberg, Germany and is under-taking an apprenticeship as a librarian at the University of Bre-men. Lena is using a service robot 'FRIEND' and its Schunk lightweight arm as a tool to support everyday tasks to allow au-tonomous environmental interaction. Now, the robot specialists from the Institute for Automation Technology (IAT) Bremen have modified the mechatronic helper so that Lena Kredel can inde-pendently catalog the books in the university’s library.

“Friend is a stroke of luck for me," said Lena Kredel. The abbreviation 'FRIEND' stands for 'functional robot arm with user-friendly interface for disabled people'. At a first glance the unit looks somewhat bulky. The electrically powered wheelchair is equipped with a monitor, mul-tiple sensor systems and as a central element, a lightweight arm from Schunk, the competence leader for clamping technology and gripping systems. With a joystick at her head and via voice recognition, Lena Kredel controls her assisting robot to record books with standard software for libraries using an internet browser for research. In the course of time, 'FRIEND' really did become a true friend for Lena. Using 'FRIEND' has brought a great deal of pleasure, and it is obvious that Lena enjoys the freedom and independence from the system.

Humans and Robots working hand in hand

Since 1997, the IAT Bremen has conducted research on robot-supported assisting systems. Today, the solution that is used by Lena Kredel is the fourth generation. The system is based on a concept of shared autonomy. Things that can be independently solved by the robot, are done by the robot itself. If it reaches its limits, the user intervenes for correcting the gripping position or if unforeseen disturbances occur. According to Torsten Heyer, project manager at IAT, presently about 95% of all processes can be solved this way without any external help.

For ensuring perfect teamwork, the environmental conditions are au-tonomously recorded via a three-dimensional camera and an infrared camera that are positioned over the head of the user. When Lena Kredel starts the system, the camera locates the bookshelf, the books and the storage position automatically. Then, the Schunk lightweight arm approaches the determined position autonomously. Markers and colored markings are used by the system as a point of reference. The control of the whole gripping system is carried out by Lena Kredel. For this purpose, the system has been equipped with numerous features, that allow assessment and control of the gripping process. A camera on the robot gripper continuously transmits live pictures of the gripping process. These are immediately visible for the user on a monitor. At the same time the camera can be used as a reading lens that makes even small print readable. If the system should approach its limits, Lena Kredel intervenes.

Versatile lightweight arm

The central element of the assisting robot is the LWA 3.10 lightweight arm from Schunk, a modularly integrated gripping arm with seven degrees of freedom. The system uses three degrees for orientation, three for positioning and one for bypassing obstacles. In contrast to classic industrial robots, the lightweight arm is designed for automating the direct environment of a human. This includes inspection and assembly tasks and also the use of assistance systems.

A permanently high repeatability of +/-0.1mm ensures optimum con-ditions for precise gripping operations. The maximum payload of the gripping arm amounts to 10kg. At a battery-servable power supply of 24V, the average power requirement is below 3A. If no socket should be available, or if the system is used completely mobile, the assis-tance robot may be self-sufficiently operated by the standard wheel-chair battery for about two to three hours. In order to exclude the risk of injury, the IAT has equipped the assistance robots with force-moment and spacial monitoring sensors.

As the drive amplifier and controller are directly integrated in the lightweight arm, the system does not require a control cabinet. The complete control and regulation electronics are integrated in the joint drive. Position, speed, and torque can be flexibly adjusted. With inte-grated intelligence, universal communication interfaces and cable technology for data transmission and power supply, the arm can be quickly and easily integrated into existing concepts. Moreover, it is controlled via an embedded personal computer.

As the assisting robot has to cover a gripping radius of 180cm, it ap-pears bulky at first glance. Credit to the consistent modular program from Schunk, Torsten Heyer says that changing to the more compact Powerball lightweight arm LWA 4.6 is now possible.

Assisting systems can be operated by amateurs, too

The lightweight arm is programmed via the Schunk interface. The in-dividual movement strategies were developed by IAT. According to Christos Fragkopoulos, at the IAT, programming has been easy: “We control the speed or current via the interface. How the modules are working with each other depends on the individual program. This be-longs to the scientific work carried out by IAT.”

At the beginning, the pure handling time for an individual book was 17 minutes, now Lena Kredel requires between five and seven minutes for handling and 15 minutes for cataloging. In the next step, reliability will be increased. The aim is to achieve a success rate of 99.9% over the course of time. According to Torsten Heyer, the 'ReIntegraRob' project sponsored by the Integration Office in Bremen with €400,000, shows the hidden potentials of assisting robots.


Additional Information:

The Human Element - An Interview With Lena Kredel:

Frau Kredel has been working with the assisting robot 'Friend' for over a year. How quickly did you familiarize yourself with your mechatronic helper?
Lena Kredel: "At the beginning I had respect of this monster. When I started to train with the system I said to my assistants that I 'have to go into the robot again today.' Then I gradually learned to deal with 'Friend,' and quickly recognized the advantages. When I became able to maneuver the vehicle with the joystick, my concerns disappeared."

Did you have experience with electric wheelchairs before?
"I always had the feeling that electric wheelchairs are too obtrusive. However, I quickly familiarized myself with 'Friend'."

What is the benefit to you?
"The system enables me to participate in the working life again. I have my job in the library, and I make a contribution in optimizing this robot."

How did your friends react when they heard that you are going to work again?
"The reactions were very different. Some didn’t understand why I would expose myself to the work burden since I am handicapped. For me it is an enrichment, doing something useful. I am proud of being able to work independently."

Could you imagine that a service robot may replace your assis-tants one day?
"I am skeptical since my apartment is too small for such a system, and since my social and personal contacts are very important to me."

Are there any situations where you would wish to have such an electronic helper?
"In case of personal matters, the technology can be very valuable help. I am already using technical solutions for writing letters or for making a phone call. It makes me independent. But I can also imag-ine such an assistance system for eating."