A variable stiffness soft gripper using granular jamming and biologically inspired pneumatic muscles

As the domains in which robots operate change the objects a robot may be required to grasp and manipulate are likely to vary significantly and often. Furthermore there is increasing likelihood that in the future robots will work collaboratively alongside people. There has therefore been interest in the development of biologically inspired robot designs which take inspiration from nature. This paper presents the design and testing of a variable stiffness, three fingered soft gripper which uses pneumatic muscles to actuate the fingers and granular jamming to vary their stiffness. This gripper is able to adjust its stiffness depending upon how fragile/deformable the object being grasped is. It is also lightweight and low inertia making it better suited to operation near people. Each finger is formed from a cylindrical rubber bladder filled with a granular material. It is shown how decreasing the pressure inside the finger increases the jamming effect and raises finger stiffness. The paper shows experimentally how the finger stiffness can be increased from 21 to 71 N/m. The paper also describes the kinematics of the fingers and demonstrates how they can be position-controlled at a range of different stiffness values

Entwicklung eines elektromechanischen Stellantriebs fuer den "brake by wire"-Einsatz mit der DLR-Planeten-Waelz-Gewinde- Spindel

OP 970115

DLR Multi-fingered Hands

This chapter describes the history of development of multi-fingered hands at the Institute of Robotics and Mechatronics, German Aerospace Center (DLR). It provides an overview of kinematics, actuators, and sensors used in different hands, including DLR Hand I and DLR Hand II, Spacehand and Awiwi Hand, discussing also the lessons learned during the development process and the usage of the hands. A more in-depth description of the most recent DLR development, the Awiwi Hand, is provided to illustrate in detail the challenges of the design of robotic hands, including the consideration of functional aspects that guarantee achieving the required performance in these end effectors

Variable Impedance Actuators: Moving the Robots of Tomorrow

Most of today's robots have rigid structures and actuators requiring complex software control algorithms and sophisticated sensor systems in order to behave in a compliant and safe way adapted to contact with unknown environments and humans. By studying and constructing variable impedance actuators and their control, we contribute to the development of actuation units which can match the intrinsic safety, motion performance and energy efficiency of biological systems and in particular the human. As such, this may lead to a new generation of robots that can co-exist and co-operate with people and get closer to the human manipulation and locomotion performance than is possible with current robots

3-Iodo-2-propynyl butylcarbamate (IPBC) [MAK Value Documentations, 2011]

The German Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area has re‐evaluated 3‐iodo‐2‐propynyl butylcarbamate (IPBC) to establish a maximum concentration at the workplace (MAK value), considering all toxicity endpoints. Available unpublished study reports and publications are described in detail. IPBC is irritating to the eyes and respiratory tract and has a skin sensitizing potential. New data have substantiated the previous designation with “Sh”. In a 5‐day aerosol inhalation study in rats, hyperplasia, squamous metaplasia and necrosis of the underlying cartilage of the larynx were observed at 1 mg/m3 and above. These effects were observed to an increased extent in the 13‐week study, in which the NOAEC was 0.23 mg/m3 and the LOAEC 0.3 mg/m3. Since the laryngeal irritation is the most sensitive endpoint, a MAK value of 0.1 mg/m3 (0.01 ml/m3) is established. IPBC has been attributed Peak Limitation Category I for local effects with an excursion factor of 2, since there was no direct sensory irritation but rather a tissue alteration and the NOAEC of the 5‐day study was 3 times the MAK value. In rats IPBC caused no tumours in an oral 2‐year carcinogenicity study. Increased number of liver adenomas in male mice might have been caused by liver enzyme induction. Available studies in vitro and in vivo provided no evidence of a specific genotoxic effect. Therefore IPBC is not classified as carcinogen or germ cell mutagen. In rats and mice, there was a sufficiently high difference between the oral NOAEL for developmental toxicity scaled to a concentration at the work place and the MAK value. Therefore IPBC is classified in Pregnancy Risk Group C. Skin contact will not significantly contribute to the systemic toxicity of 3‐iodo‐2‐propynyl butylcarbamate