Lightweight design of arm-like systems by coupling topology optimization and bio-inspired drive optimization

• Applicants: Professorin Dr.-Ing. Beate Bender; Professor Dr.-Ing. Axel Schumacher
• Subject Area: Lightweight Construction, Textile Technology
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 529212372

In the project, a method is to be researched with which it is possible to optimize both the topology of the associated structural design of armlike systems, and design parameters of the drive concept at the same time. These systems must be as light as possible, both for reasons of resource efficiency and for favorable dynamic behavior. The weight of the system can be reduced by independently optimizing the structural design and the drive concept. Weight reduction can be further improved by optimizing structure and drive system at the same time, which enables to consider, e. g., the influence of the drive masses on the structure. Combined optimization of actuation and structure topology is also important when drives can actively influence the load distribution in the structure through the driving forces. In biology, an approach is described for the musculoskeletal system called "tension chording principle" with which such an influence takes place via muscles. The approach is considered as one of several reasons for the low bone mass. The technical implementation of the approach is possible through drive concepts with linear drives and drive concept optimization. The drive weight and the design space of an arm-like technical system both depend heavily on the chosen operating principle of the actuator (DC motor, hydraulics, pneumatics, muscle, ...), its performance class and the gear (direct drive, harmonic drive, cable drive, belt drive, ...). Consequently, a generalized treatment of the lightweight potential of the approach is not trivial. Design parameters of the drive concept are the number, position, and angle of attack of its load application points. The topology optimization allows the structure to be optimized for certain optimize load cases and various objective and constraint functions. It will be crucial what modeling effort and degree of automation corresponds to what lightweight design potential and benefit to research. To this end, the question to be addressed is how the simulation models must be detailed to be able to represent the lightweight design potential. In addition, it should be clarified which input and output variables are available, and which must be assumed to be necessary. The result is going to be an automatic process that can be used to optimize different arm-type systems. To consider all relevant influencing factors means to strive for enabling an automated optimization with influencing variables from different types of simulations or the joint optimization of several sub-problems (multi-level optimization). The efficiency of the optimization is going to be improved using design heuristics. In particular, the technical tension chording principle is used for bio-inspired drive optimization to design selected examples of arm-like systems.

• DFG Programme: Research Grants