The ‘freeMoVe’ research project was an important part of the funding programme, focusing on developing a new form of organisation for adaptable, high-variant assembly involving small quantities down to lot size 1. The new form of organisation was based on the opportunity to specify the processing locations and sequence for each product individually according to availability. To do this, planning, design, control, information provision and the required adaptable technology were further developed.
In addition to developing the organisational form, various technological components arose as key developments. They included a feature-based control and guidance system with plug and produce functions, mobile robots, flexible feeding, gripping technology and station technology.
Design & control of freely linked assembly systems
In the freeMoVe project, the Laboratory of Machine Tools (WZL) at RWTH Aachen University investigated the design and control of freely linked assembly systems together with end-users (Infineon AG, ZF Friedrichshafen AG, Philips Innovation Services (PInS)) and suppliers (Zimmer Group, Ifsys GmbH, Henkel + Roth GmbH and Istec GmbH), supported by the Fraunhofer Institute for Production Technology (IPT). Freely linked means an assembly system that provides a flexible assembly sequence as an order route for each individual product without time or space related restrictions. An order route describes the processing locations selected for the assembly of a product and the sequence of these locations. In contrast to an inflexibly linked assembly system in which the order route is specified when the assembly system is designed, dynamic order routes are characteristic of freely linked assembly systems. The order route is determined individually for each order and tracked continuously, taking the availability of suitable assembly resources (such as unavailability due to maintenance or a fault) into account. The control system uses optimisation algorithms to maximise the efficiency of the assembly system.
Adaptable station technology
Zimmer Group was primarily responsible as an enabler for the area of ‘adaptable station technology’ in the freeMoVe research project. The company’s focus was gripping technology on mobile robots or the development of adaptive, flexible gripping technology. Handling individual workpieces or assemblies is an elementary task in industrial assembly & adapting it to changing products is time-consuming and costly. Wide, controllable lifting and gripping force ranges and easy adaptability of gripper jaw geometry are important requirements for adaptive gripping technology. In the freeMoVe project, Zimmer Group developed three different adaptive gripping systems for different applications. In the process, they also considered the possibilities of modern electric gripping systems, which enable tactile work through infinite force and speed adjustment.
Adaptive gripper systems
A flexible gripper system that holds the devices securely in individually specified positions was developed for transporting a wide variety of production devices via robots. Consisting of several electric grippers, the system is characterised by its extreme versatility and flexibility. It has a large adjustable stroke in the X- and Y-directions and allows classical force and form fit in addition to pilot-controlled prepositioning and gripping. Further features of the system include streamlined dimensions for use on lightweight robots. In addition, all relevant gripper parameters can be configured in advance.
Interchangeable finger systems
In a second application, Zimmer Group developed an innovative, completely new interchangeable finger system for handling a wide variety of suspension components (tie rods). By adapting the product-side gripper jaw geometry, a wide variety of components can be gripped securely. However, systems with soft materials usually cannot guarantee that the component in the gripper can be positioned precisely. Therefore, the entire gripper is often exchanged using a tool-changing system on the robot, which leads to high costs. With the new interchangeable finger system, only the gripper fingers are exchanged, which significantly reduces the number of redundant grippers. The gripper fingers can still absorb forces in all spatial directions. Neither tools nor additional drives or sensors are required for this automated exchange, as this is done by the movement of the robot. The process is robust and maintenance-free. The system has a modular design, can transfer compressed air or a vacuum, and is easy to integrate into applications.
The third application investigated how to use the elasticity of the gripper fingers to handle components with high process and geometry related tolerances. To achieve this, Zimmer Group developed a special gripper finger design that allows the flexibility to be specified according to the material used. In interaction with a universal feeding system, the gripping process demonstrated its reliability. To simplify gripper exchange and for applications in the field of human-robot collaboration and on mobile manipulators, an ‘end-of-arm’ modular system was developed. Using a tool-free, mechatronic quick-exchange system including air, power and signal transfer, multiple grippers, camera systems and sensors can be connected to the robot flange directly and without external cables. The sensors exchange their information with the robot control and are parameterised and operated accordingly. In recent years, Zimmer Group has developed HRC (human-robot collaboration) grippers for a wide variety of applications. The grippers have been certified by the German Social Accident Insurance Association, DGUV.
Courtesy: Zimmer Group