Automated assembly of the

wire harness in the vehicle

Theoretical evaluation of motion kinematics and creation of a demonstrator

Automated assembly of the wire harness

Automated assembly of the wire harness in the vehicle

Sub-project 8 is working on innovative and automated assembly concepts for flexible wire harness components. Automated manufacturing presents various challenges with regard to the positioning and orientation of components in the workspace.

Starting point and motivation

After the sub-assemblies have been delivered by the suppliers, they are assembled into the finished vehicle at the OEM plant. Unlike shell construction or paintwork, for example, final assembly often still involves a great deal of manual work.

This is especially true for the installation of the wire harness in the car body. Even before the carpets or seats are fitted, up to six employees lay out this assembly, which weighs between 25 kg and 50 kg, in the car body and then lay out and thread through the individual strands. The electrical connections are then joined and the fixings installed.

The automation of these peripherals is particularly exciting: unlike discs or brake lines, for example, these are flexible parts with significant mass and large dimensions.

Current working focuses

The first step of SP8 examines the process section from the removal of the assembly from the staging area next to the vehicle to the laying of the up to 65 mm thick main strands. In the current project phase, the participants are concentrating on two fields of action:

  • Research and evaluation on the laying of bundles using robots.

One major challenge for automated manufacturing is the handling and orientation of the wire harnesses by robots in the workspace. There are three important points that need clarifying here:

Modelling
In cooperation with the University of Stuttgart, the behaviour of such a non-homogeneous bundle is being modelled. The models and their parameters must reflect the actual behaviour in terms of bending, torsion, winding, tension, etc. Parameterisability is of particular importance, as the bundles differ in their composition and size depending on the vehicle.

Coarse or fine localisation of components and environment
The rough localisation is necessary for laying out the wire harness (this is usually moved into the vehicle in bundles) in the target workspace. This is also where the first positioning along the main installation routes takes place. Fine localisation is used for automatically reaching the end position of the individual plugs at the connection points. To achieve this, suitable hardware (camera) and associated software components have to be selected and integrated into the assembly process. The aim is to follow the different conceptual approaches and validate them through specific evaluation criteria.

Trajectory planning
Here, movements that are, to a certain extent, intuitive during assembly by humans need to be mapped in hardware and software being used by robots. Collisions with the environment or people working in the immediate area must be avoided, forces and angles must be controlled and monitored to ensure the quality of the product.

  • Practical investigation of different concepts with the help of a demonstrator

In order to examine concepts and models practically afterwards, the team selected a representative sub-area. A partial scope, known in the trade as a “short sample”, is examined in terms of its behaviour in a real environment (vehicle body). If an approach passes this first test, a significantly larger, second object is then built.

Interdisciplinary cooperation

The team consists of specialists from across the entire value chain (component manufacturers, assembly system suppliers, machine manufacturers, OEMs) and is reinforced by experts from the University of Stuttgart.

In a successful mix of online conferences and face-to-face meetings, the individual steps are planned, new things are creatively imagined, and they are jointly detailed and examined. In particular, the interdependencies between individual steps can thus be incorporated into the new approaches and their assessments at an early stage.

Outlook

After the first installation of a demonstrator in a real car body, we will investigate two focal points:

  • Extension of the dimensions to the entire vehicle
  • How can robots and humans work together advantageously in this close environment?