Speakers
Description
The interaction between actuation and mechanical structures causes complexity in lightweight design optimizations of arm-like manipulators, e.g., industrial robots. While changes in the actuation concept cause changes in load cases which lead to different optimized structures, changes in structural components influence their inertial properties which influence the required actuation forces or torques for predefined motions. Design and parameter changes in actuation and structure have an impact on the overall system. Optimization is a way to combine the design of actuation and structure.
The human musculoskeletal system is an example of an optimal system that considers the interaction between structure and actuation. Muscle contractions cause bone movement because they are connected via tendons. The application of force via the tendons minimizes bending stresses in the bones. Bone structure absorbs the resulting compressive stresses optimally. In arm-like manipulators, bending is as important as in the human arm. For technical applications, actuation concepts based on the human musculoskeletal system use, e.g., ropes to move the components and influence bending.
In this contribution, a coupled optimization problem with a nested loop is formulated to coordinate a rope-based actuation design with a topology optimization. With a multibody simulation (outer loop) and a predefined motion with an external load at the end effector, static load cases are derived for topology optimization (inner loop). The structural properties of the optimized structure:
- Masses
- Center of gravity
- Moments and product of inertia
are considered in the next multibody simulation, which provides new load cases for topology optimization. This repeats until the structural properties and the objective function of the topology optimization converge. This process is done for different actuation concept parameters, e.g., rope end point positions. The different results show the complexity between actuation concept parameters and topology-optimized structure.
