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Fraunhofer-Institut für Produktionsanlagen und Konstruktionstechnik IPK
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PublicationPowerGrasp - Design and evaluation of a modular soft-robotic arm exosuit for industrial applications( 2020)
;Thiele, Gregor ;Schmidt, H. ;Hackbart, R. ;Kostelnik, J. ;Liebach, J.Wolschke, M.Absence from work caused by overloading the musculoskeletal system lowers the life quality of the worker and gains unnecessary costs for both the employer and the health system. Classical (rigid link) body-worn exoskeletons can help to reduce critical loading but show many disadvantages, preventing exoskeletons from extensive use in industrial environment. The presented PowerGrasp system is a very robust modular softrobotic arm exosuit sting of robust fabric with embedded rubber tubes as pressure chambers and soft-electronics and who's design is capable to overcome the critical limiting factors of classical exoskeletons. By inflating the tubes via pressure-control valves, it is possible to vary the stiffness of the chambers, which can be effectively used to generate assisting forces and moments at human joints. By using a joint based pressure control, it is possible to decrease the physical demand of overhead working for the wearer. Although the system is designed for i ndustrial overhead assembly, it can also be used in rehabilitation, craftsmanship and construction due to its portable and stand-alone concept. For assessing the impact of the PowerGrasp system, the raise of about 50 percent was shown. Finally, an evaluation study of the overall system has been conducted, showing very high user acceptance and usability. -
PublicationPowerGrasp: Concept for a novel Soft-Robotic Arm Support System( 2018)This paper presents a novel concept and first modules for a soft-robotic arm support system for application in overhead assembly in automotive industry. Repetitive manual tasks and associated body movements are still typical in industrial assembly jobs. Even without an additional load or tool, such tasks are monotonous and often lead to stress in the musculoskeletal system, which frequently causes pain and injuries. In light of ageing industrial workforce, solving this problem becomes a major challenge for ergonomics researchers and engineers. In this paper we present a novel active soft orthotic device which is not an exoskeleton, even though there are some similarities. It is designed to induce only moderate external forces into the human skeleton for muscle fatigue compensation, without causing harm. The concept involves different soft-robotic actuators, depending on the human arm joints to be supported, as well as concepts for control, energy storage and sensors. By detecting muscle fatigue of the worker we created an active assist-as-needed system, which has advantages in energy consumption on the one hand and prevents muscle atrophy of the worker on the other hand. To fulfill these requirements we developed pneumatic actuators, which adjust themselves to the user without external calibration. This automatic calibration process requires no special knowledge of the employees and takes place only by using separated pneumatic chambers and adjustable straps and buckles. By using strain gauges and inertial measurement units, as well as pressure sensors and force sensors we measure and analyze all necessary information for the position related force control in real time. We also present first evaluation results with static overhead retaining tasks.
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PublicationSmartSensX. Ein Konzept für vernetzte tragbare Sensoren zur Anwendung in der Softrobotik und Mensch Maschine Interaktion( 2018)
;Hackbart, R. ;Kostelnik, J. ;Vieroth, R.Lang, K.-D.Technical support systems, such as soft orthotic assistive robots or exoskeletons, provide an additional level of interaction between humans and the environment. Knowledge of physical parameters (e.g. speed, distance, etc.) in this level enables the use of active, controlled support mechanisms. Therefore, in the context of support systems close to the human body and in soft robotics, it is necessary to develop "soft sensor systems" that present new possibilities in design and application. SmartSensX is the implementation of a sensor network consisting of a main unit and several sensor modules with inertial sensors worn close to the body. The sensor modules have the character of embedded systems - they can be connected or disconnected during operation (plug and play). The concept enables the integration of various other sensor types by using a common transmission protocol. Data transfer takes place by wire on elastic, skin-compatible printed circuit boards made of polyurethane (TWINflex-Stretch) or textile-integrated on e-textiles. Another possibility for data transfer between the main unit and sensor modules is the USB 3.1 Type C interface. The sensor modules are arranged in a bus topology. Differential signal transmission is used to increase the sensor modules' robustness against signal noise. The measured values of the sensor network are recorded, processed, and transmitted in real time.