Model Based Programming of Fiber Ply Pick and Drape Processes

Publikation: AfhandlingPh.d.-afhandling


Laminated composites exhibit attractive material characteristics such as high strength-to-
weight ratio and resistance to corrosion. The usage of composites is ubiquitous in industries
such as automotive, aerospace, and wind, with the usage being expected to increase. Currently,
the manufacturing process for components made out of composites is expensive and time con-
suming, as the manufacturing is mainly done manually. Large batch production has been auto-
mated to some degree, often utilising solutions specialised for a single component. This type of
automation is not feasible for businesses producing small-to-medium sized batches of multiple
components. There is thus a market for flexible, automated systems, geared towards small-and-
medium batch production.

The goal of the FlexDraper research project is to develop a highly flexible, automated solu-
tion to the composite layup process. The proposed system is aimed at double curved moulds
with low-to-medium curvature, and can automatically plan and execute a draping sequence
based on the ply and mould specifications for the part being produced. The solution is a drape
tool consisting of a rectangular array of interlinked suction cups mounted on linear actuators.
The suction cups have passive joints allowing the grid to imitate the shape of the mould. The
proposed solution differs from other systems in the literature in that the suction cups can be
individually extended, and the orientation is affected by the neighbouring suction cups.

The focus of this thesis is on model-based path planning for the FlexDraper drape tool. The
proposed path planner approach consists of two subproblems: 1) Based on a model of the drape
tool, predict the poses of all suction cups given a set of actuator extensions, and 2) using this
model to search for a robot pose and a set of actuator movements to place the suction cup in a
desired configuration. Initially, we derive a model based on dynamic simulation of the drape
tool. The mechanics of the system allow multiple admissible poses for a single set of actuator
extensions, resulting in the need to upgrade the drape tool. Interlinking springs were added to
the drape tool improving the positioning of the drape tool. We derive two new models based
on energy minimisation for pose prediction. The first model calculates the spring energy using
a cubic spline approximation of the spring shapes, while the latter model is based on a straight
line approximation to the spring shape. The resulting models can, in the general case, predict
the positions of the individual suction cups within 1.5mm. A path planner was created, utilising
the models to realise draping sequences. The path planner method receives a specification for
a drape sequence as input, and minimises the pose difference between the suction cup pose
predictions and the desired configurations.
  • Petersen, Henrik Gordon, Vejleder
StatusAfsendt - 1. dec. 2020

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