Mechatronic Machine Elements
Most technical systems are information processing systems – from conventional mechatronic systems to the highly integrated cyber-physical systems used in the context of Industry 4.0 and Internet of Things. The functionality of these systems depends on information about machine state or process parameters, which is generally obtained by sensors. For practical reasons – e.g. because of space restrictions, to protect the sensor from disturbances or because the process would be disturbed by the sensor – the interesting variables often cannot be measured in situ, but have to be calculated from other measured quantities using some form of model. The accuracy of the information is thus dependent on the accuracy and quality of the underlying model. Particular attention must be given to the “distance” between the interesting variable and the actually measured quantity, because the spatial distance increases the chance of disturbances not included in the model affecting the measured variable.
The idea behind “Mechatronic Machine Elements” is to reduce these uncertainties by integrating sensing, actuating, information processing and information transmitting functions into machine elements and mechanical components. Machine elements are standardized components of mechatronic systems used in many applications, thus offering some potential for standardization of sensors once successfully integrated. Moreover, they are deeply integrated in mechatronic systems and fulfill important functions: In the pictured example, the machine element connects two subsystems. By integrating sensing and actuating functions in this interface, the system’s behavior can be monitored and controlled more directly than with external sensors and actuators. The model used to obtain information about the system state can be simplified as a consequence. Furthermore, fewer sensors and actuators are needed outside the mechanical system (dashed lines).
Example of use
The advantages of sensor-integrated machine elements can be explained for the context of a double clutch (picture source: Schaeffler Group). When a torque measurement can be realized in the clutch discs or in the pressure plate without major redesign by integrating the sensor into existing components, the torque at each of the clutch plates is directly available as an accurate measurement result. This eliminates the need for complicated friction models, which are normally necessary to calculate torque based on other measurements. This simplifies control of the clutch and facilitates functional safety according to ISO 26262, because the catastrophic event of a simultaneous engagement of both clutches could be detected reliably. It can be seen that the benefits are often on system level rather than machine element or component level.
Possible applications of Mechatronic Machine Elements are
- recording load spectrums for dimensioning purposes,
- integration of sensors in existing designs by replacing machine elements,
- monitoring and control of production processes,
- identification and elimination of assembly errors by measuring shaft misalignment or bearing reaction forces,
- measurement of disturbing vibrations introduced via bearings,
- condition monitoring and predictive maintenance.
The research approach of pmd considers four aspects:
- From an application perspective, the most important research question is: What kind of information can offer additional benefit for the product or the company, and which measurement and data processing technologies can obtain this information in a robust way?
- A thorough understanding of the mechanical behavior and the properties of machine elements is necessary to ensure a predictable and reliable behavior of functionally integrated machine elements.
- Possible design implementations of machine elements with integrated sensors or actuators are developed including the elimination of disturbing effects of product tolerances and operational conditions.
- Experimental and numerical investigations are conducted to improve the understanding of the components and systems and to validate theoretical findings in a real-world environment.
- development of a smart parallel key with integrated torque measurement
- development of smart compensating couplings with integrated measurement of torque and shaft displacement
- development of signal and energy conducting roller bearings
The development and application of conventional and innovative machine elements is taught in “Machine Elements and Mechatronics II” and especially in the advanced courses “Innovative Machine Elements I + II”.
Our goal is to cooperate closely with industry partners, in order to apply and advance our research in industrial development and research projects. Feel free to approach us with your ideas for cooperation!
Finished Student Papers:
- Analysis of characteristical internal loads of key connections
- Analysis of Technical Weak Points of Smart Compensating Couplings
- Condeptional ans emodiment design of a test rig for smart feather key experiments
- Development of a Test Bench Concept for the Examination of Power Conduc-ting Roller Bearings
- Investigation of application potential of smart keys by analysis of representati-ve use processes of keys
- Investigation of common properties of Machine Elements for integration of sensors
- Investigation of the impact of the detailed geometry on the friction moment in the head of a hexagon head bolt with flange
- Determination of the devision of the load path in preloaded shaft-hub-connection by FEM