The »third arm« for craftsmen makes two aims possible: Effective support of the craftsman on the one hand and computer-generated additional information directly in the place of action on the other hand.
»Getting technology to humans« – Under this heading, a research project for developing a craftspeople-power-system with adaptive human-machine interaction started in 2014, promoted by the German Federal ministry of Education and Research.
That »third arm« for support during physically demanding work should fulfil specific functions as an overall system, namely: power assistance for load reduction and lowering fatigue, merger of different measurands for position monitoring and projection of relevant information into the workspace (augmenting), intuitive handling and adaptive customization to the behaviour of different users and working environments.
The augmenting function, following the concept of augmented reality systems AT as key component of the »third arm«, transfers additional information about the work to be performed to the craftsman via fade-ins.
Coordinator of the project was the company Würth Elektronik Circuit Board Technology (CBT), project partners were the Karlsruhe institute for technology (KIT), the Centre of mechatronics Hannover (MZH), Robert Bosch GmbH in Renningen and other stakeholders from industry and craft trade.
»Würth Elektronik CBT, in its role as general project coordinator and technology provider had responsibility for the technical realization of the sensor systems, the development and production of electronics as well as for the provision of demonstrators«, explains Dr. Jan Kostelnik, Head of Research & Development at Würth Elektronik CBT.
During the project and as an initial step, various options had been analysed to realise printed- circuit based strain gauges with flexible carbon paste variations on flexible sub-strates. A multi-axle force sensor built in that technology was supposed to measure the kind of forces acting on the exoskeleton during every move of the craftsman. »That happens by relating the bend of a flexible polyimide-circuit and the external forces to each other«, illustrates Dr. Jan Kostelnik.
Farther-reaching actions included the development of a complex sensor and actuator concept, in concrete terms the design of an appropriate drive on the influencing factors expected, for example on the weight forces emerging from heavy machines which so far had to be endured by the craftsman. The specification of the sensor and actuator concept was set in cooperation with the project partner MZH.
Moreover, the multitude of various sensors collecting and transferring measured data from different places of the »third arm« implied the necessity to design a communication bus system. For that purpose, USB3.1 type C connections were deployed for the physical data transmission. Energy supply to the sensors can be provided via the physical bus system as well. Würth Elektronik implemented USB 3.1 type C cables and plug connectors in a robotic project for the first time in the world, thus could represent a ground-breaking new standard for robotics and other systems.
In addition, power electronics had been designed and produced for the electronic actuators‘ power supply. A mainboard – realized in cooperation with Bosch – contains all interfaces provided in the sensor and actuator concept. A 36-volt-battery had been integrated to autonomise the »third arm«. Another focus of electronics development was the battery management system.
The work-related assessment of the demonstrator was carried out by the ifab-institute of the Karlsruhe Institute for Technology. »Our approach were three use cases in practical application: Working overhead with power tools, chiselling work with heavy electric devices and repetitive work with a long-neck sander in dry walling«, summarises Dr. Kostelnik the relation to craftspeople work practice. In trials with the test persons, the systems‘ fitness and interaction schemes were evaluated by analyses and assessment of the use cases.
»Working in the project of the Federal Ministry of Education and Research brought us essential steps forward. Especially MZH’s work on an augmenting function, means the collection of spatial data by a camera and the itself adapting projection of work schedules like e.g. drill holes imposed great demands. Of course, we have not yet reached the target of serial production, but the findings obtained will be incorporated in new research projects«, recapitulates Dr. Jan Kostelnik of Würth Elektronik CBT.