Optidrap - Model predictive impedance control of pneumatic continuum actuators in the continuous wet draping process

High-performance components made of fiber composites with complex geometries can be manufactured automatically using draping processes. The complexity of the shape is determined by the draping capability of the system and the controlled placement of the semi-finished textile product. Simulations show that uniform stress equalization is achieved by depositing the material along a geometry-specific draping line, which can be described as a 3D spline. A form-flexible, pneumatically operated pressing element with continuum actuators (CA) was developed to continuously press the textile along this line. The OptiDrap research project is investigating how textile tension can be actively controlled by adaptive adjustment of the draping line and model-based impedance control of the CA. The aim is to research and model the interactions between the textile, tool geometry, and pressure element in order to develop a tension-dependent process control system. This should significantly improve process understanding, manufacturing quality, and productivity.

Objectives

The objective of the project is to develop a process and system model to describe the interactions between textiles, tool surfaces, and flexible pressure elements in the continuous wet draping process. This model will form the basis for model predictive impedance control, which continuum actuators can use to implement draping lines that adapt to textile tension. This enables active tension compensation in the textile during deposition and thus a wrinkle-free draping result even with highly complex shapes. Sub-goals include the experimental and simulated recording of process interactions, the expansion of existing models to include a spatial description of CA deformation under real forces, and the development of a real-time control architecture for adaptive process control.

Benefits

The models and control approaches developed in the project offer several advantages and significant practical benefits:

• Wrinkle-free components: Active tension compensation significantly improves drape quality, reducing rework and scrap.
• Increased productivity: The continuous, automated process shortens production times and reduces manual intervention.
• Technological and knowledge advantage: Companies gain a better understanding of the complex interactions involved in wet draping and can transfer this knowledge to new applications.
• Competitive advantage: Improved process quality and efficiency strengthen the position in the production of highly complex fiber composite structures.

Approach

The project experimentally investigates the continuous draping of carbon fiber-based semi-finished textile products in order to understand the interactions between textiles, draping kinematics, and surface geometry. To this end, experiments are conducted with different types of textiles, fiber orientations, and component geometries, the textile tension is measured across the width, and draping errors are recorded. Based on this, the process model is expanded and draping lines are calculated depending on geometry and tension. At the same time, continuum actuators are modeled and integrated into a system model of the pressure element. Based on this, a model-predictive impedance control for adaptive textile tension compensation during draping is developed and experimentally verified.

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Contact Lucas Wolf via email at wolf@ifw.uni.hannover.de or by phone at +49 4141 77628 15.