Our projects include for the most part interdisciplinary research projects, which are carried out in worldwide cooperation with our partners.

The purpose of clamping systems is to clamp rotary shafts during operation preventing them from moving even when torque is applied. They are used in CNC machines, for example, where they make an important contribution to achieving high machining precision. The clamping systems from HEMA, called RotoClamp, work pneumatically so that they are not dependent on high oil pressures. This high-precision assembly is dependent on regular maintenance intervals, and serious damage can be expected if the clamp fails.

This project, supported by LOEWE funding line 3 (1197/21-198), aims to work with HEMA and Core Sensing in order to record and interpret operating data in real time and provide recommendations for action to prevent failures and damage to machine parts. The project opens up new opportunities in the field of digital services and predictive maintenance, with the Department of Measurement and Sensor Technology driving forward application-oriented research in these areas.

The project was completed with great success in June 2023. We would like to thank the project partners and the state of Hesse.

For many applications, such as structural health monitoring, medical applications, autonomous vehicles and environmental monitoring systems, the need for sensor networks steadily increases. Often, the sensors are positioned at remote places where the availability of electrical power or possibilities such as replacing or recharging batteries are challenging tasks. Therefore, other methods for powering electronic circuitry, such as energy harvesting, have been a growing field of study for the last 20 years.

The objectives (DFG Project number 392020380) of this project are the design of new ferroelectret materials and their use in energy harvesters based on the transverse piezoelectric effect in these materials.

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3D representation of the air-spaced cantilever energy harvester (published in Applied Physics Letters).
3D representation of the air-spaced cantilever energy harvester (published in Applied Physics Letters).

Structural integrated force and torque sensors are increasingly required in fields such as monitoring in plant construction, medical engineering and light weight construction. All these fields share the requirement of complex structures. Thus, an integration of commercial general-purpose sensors, which are conventionally manufactured, is not possible or only with considerable effort. Conventional manufacturing methods based on machining the deformation body and subsequent application of strain sensing elements limit the design geometry and size of a deformation element. Additively manufactured force and torque sensors create added value as they allow a high degree of individualization and adaptation to application-specific needs.

In this project (DFG project no. 418628981), the fundamental aptitude of additive manufactured deformation elements with laser-based powder-bed-fusion for force sensors is investigated. The objective of this project is to develop reproducible methods for the structural integration of strain sensing elements in additively manufactured components with force sensing function.

Completely encapsulated force sensor based on Laser powder bed fabrication process.
Completely encapsulated force sensor based on Laser powder bed fabrication process.

In general, the term cooperation is defined as working together towards a common goal. Successful cooperation requires mutual adaptation based on the perceived behavior and communicated intentions of the counterpart. In the case of a physical interaction, e.g. jointly moving an object, a significant amount of this information is exchanged via the haptic channel. For this purpose, one needs to discriminate between self-originating and externally induced sensory input.

In this project (DFG project no. 402740893) within the priority program The Active Self, we investigate the underlying principles of such an interaction and transfer these findings to human-robot cooperation in order to make it more intuitive to the human.

A successful cooperation between human and robot requires mutual perception.
A successful cooperation between human and robot requires mutual perception.

The main application of cardiac catheterization is the in-depth diagnosis and treatment of arteriosclerosis. Various types of deposits (plaque) in the coronary arteries can lead to a reduction of the internal cross-sectional area, thus to reduced blood flow and consequently to heart attacks. For minimally invasive diagnosis and treatment of arteriosclerosis, a thin guide wire with a diameter of 360 μm is used. This guide wire is inserted usually through the femoral artery at the groin or the radial artery at the wrist into the patient's vascular system and pushed into the coronary vessels to the area to be treated. For this purpose, the physician has to navigate the wire tip, which is located in the vessel, through twisting and pushing the distal end. Difficulties arise from a lack of haptic feedback, which complicates the already complex navigation through the coronary arteries even more.

In contrast to the HapCath project, which focused on generating haptic feedback for the physician, the goal of the SMArt Guide Wire project (DFG project no. 392780747) is to facilitate navigation through a steerable guide wire. For this purpose, the integration of SMA (shape memory alloy) wires in the guide wire tip is investigated within this project. This enables an external stiffness control and an external bending of the guide wire tip.

In this project (DFG project no. 172196622), a teleoperation system with a parallel kinematic structure was developed with interchangeable surgical instruments (e.g. grippers) as end effectors and five degrees of freedom.

The main application of cardiac catheterization is the in-depth diagnosis and treatment of arteriosclerosis. Various types of deposits (plaque) in the coronary arteries can lead to a reduction of the internal cross-sectional area, thus to reduced blood flow and consequently to heart attacks. For minimally invasive diagnosis and treatment of arteriosclerosis, a thin guide wire with a diameter of 360 μm is used. This guide wire is inserted usually through the femoral artery at the groin or the radial artery at the wrist into the patient's vascular system and pushed into the coronary vessels to the area to be treated. For this purpose, the physician has to navigate the wire tip, which is located in the vessel, through twisting and pushing the distal end. Difficulties arise due to a lack of haptic feedback, which complicate navigating through the coronary vessels.

The objective of this project (DFG project no. 5429061 and 212414892) were the design and implementation of a haptic assistance system for catheterizations in medical diagnostics and therapy. The approach is based on a force measurement at the guide wire tip and an integration of a haptic control unit in the treatment process. This control unit generates haptic feedback for the physician based on the scaled force signals.

SEM image of the developed silicon miniature force sensor based on the piezoresistive principle.
SEM image of the developed silicon miniature force sensor based on the piezoresistive principle.

The daily amount of falls is increasing with increasing age and due to balance influencing impairments. In order to reduce the related number of falls and fall-related deaths, mainly physical training interventions were investigated so far.

In this project (FiF Website), we investigate novel approaches to reduce the number of daily falls by applying vibrations to the skin by contact-free ultrasound. Compared to conventional vibration motors, ultrasound allows for a versatile choice of signal shape, amplitude and frequency.