Chameleon tongue and laser scanner:
Technical Center for Production Assistance Systems
Audi’s Technology Development Production Assistance Systems department is occupied with new production technologies that support the employees in the working process. At a technical center outside the plant site, the team is currently pushing forward with five key topics. They involve human‑robot cooperation, support for the assembly employees, innovative lightweight robots, driverless transport systems and new sensor technology and display concepts.
Flexible screw points: LBRinline
On the assembly line at Audi’s Ingolstadt plant where the cars of the Audi A3 and Q2 series are produced, one model requires very special attention: the Audi A3 Sportback e-tron. The compact plug‑in hybrid differs from its sister models in various ways, in the screwing points for the underbody cladding for example.
At present, Audi uses an assembly trolley for the Audi A3 and Q2 models with conventional drive that is based on an employee suggestion. It consists of a rigid frame with 14 screws. With the so‑called “LBRinline” – a lightweight robot on the assembly line – the engineers of the technical center have further developed the assembly trolley so that it meets the challenges of increased complexity in a new, flexible way. It is an assembly trolley made of aluminum profiles with four lightweight robots on a mobile platform. An employee links up the trolley with the suspended conveyor belt, and it then moves along below the car for just over 20 seconds. The lightweight robot screws the so‑called cw underfloor cladding onto the e-tron‑model and the conventional models completely independently. A safety system with three laser scanners ensures that the robots, each weighing only 18.4 kilograms, do not come into direct contact with the employees.
LBRinline is one of many individual measures Audi is taking to make its assembly more flexible. When the robots prove their worth in daily use, their principle can be transferred to other similar types of work. For example, ergonomically difficult work overhead in production can be eliminated in the long term.
Inspired by the chameleon: flexible gripping
Many robots specialize in gripping functions. But few of the gripping arms in use nowadays are flexible. The Audi Technical Center is currently testing a gripper that perfectly manages this task: the FlexShapeGripper from the company Festo. It can grip objects, hold them, pass them to an employee or place them into a workpiece carrier.
The working principle of the FlexShapeGripper is derived from nature; it is similar to the tongue of a chameleon: An elastic cap is deformed under the influence of compressed air and spring tension. It wraps around the object that is to be gripped and firmly encloses it.
Unlike today’s gripper jaws, which can only grip certain components, the FlexShapeGripper is highly flexible. It even copes with components with free forms and curved geometries. As it does not have any sharp edges, it is also ideal for use with sensitive objects such as air vents or trim strips. In principle, the gripper can pick up several objects in one movement, several nuts from a tray, for example. The functional versatility is not yet comparable with the human hand – but it is already very close. This opens up new perspectives in the field of human‑robot cooperation.
Assembly assistance: motionEAP and “Clever Klaus”
In the context of its motionEAP research project, Audi has developed a modern assembly table. This prototype with computer-controlled assistance functions is not applied commercially. The abbreviation motionEAP stands for a system for efficiency enhancement and assistance in production processes on the basis of the recognition and projection of movements. It is a project with public funding by which Audi is collaborating with a consortium of experienced engineers and technicians.
The heart of motionEAP is an infrared depth camera – a standard “Kinect 2” from Microsoft. This is an example of how production technology can benefit from the latest developments in the gaming industry. Installed over the table, the Kinect monitors the working stage of the workpiece by comparing its actual parameters with the target parameters. A projector next to the camera then projects instructions onto part of the table – in the form of short texts, videos or images. As soon as a stage of work is correctly carried out, a green light appears. A computer controls the projector and the 3D camera.
Another system with the name “Clever Klaus” is already in use. It helps the workers on the preassembly of Audi A4 doors with the complex cabling. The model range includes several hundred different variations; in the top versions, the door trim integrates up to 14 connectors for the electric windows, loudspeakers, central locking, mirror adjusters and other optional equipment. Two high‑resolution 2D cameras above the table check whether all the cables have been connected properly. The sequence of work is irrelevant.
Hand in hand: human‑robot cooperation
Step by step, robots without protective fences are entering Audi’s production plants. They relieve the employees of ergonomically negative or monotonous tasks. Humans and robots work together in a shared area where strict safety precautions apply. Audi’s Technical Center for Production Assistance Systems is continually advancing human‑robot cooperation, with one key criterion: The employees’ safety has top priority.
Audi is increasingly testing new robots with limited strength and performance that stop immediately after any direct contact. Specific forces and pressures may not be exceeded; they are exactly defined in a norm for all parts of the human body. Extensive investigations are being carried out on this subject in Audi’s Technical Center for Production Assistance Systems. Among other things, the company is examining the following questions: How can sharp-edged grippers and the parts they are carrying be made safe? Which loads are realizable? How quickly may a robot move so that the forces remain low? And which momentum sensors are the most effective?
Ideally, the robot – including gripper and component – must be permanently surrounded by an area that moves with the gripper and workpiece depending on the situation. If a minimum distance between system and employee is not maintained, it will stop before any contact. Audi is doing research also in this area, together with suppliers and partners such as the Fraunhofer Institute. In the area of sensor technology, Audi’s development engineers are also-considering radar. It precisely recognizes movements and distances and is not disturbed by varying light levels.
New intelligence: driverless transport systems
Driverless transport systems, consisting of guidance control and one or more driverless transport vehicles, have been standard in automobile production for several decades. The electrically powered transport robots convey components, containers and in some cases – as at the Audi Böllinger Höfe facility near the Neckarsulm plant – even entire car bodies; they follow guidance wires or RFID chips in the factory floor. Audi is now giving driverless transport systems a completely new level of intelligence, making them into the backbone of modular assembly in the future (see separate chapter). The Technical Center for Production Assistance Systems has developed and set up two innovative concepts called “Audi Laser Tracking System” and “Audi AGV” (Automated Guided Vehicle).
The Audi Laser Tracking System is a system that can recognize and guide a group of driverless transport vehicles. A powerful computer locates them by means of their reflectors, using a high‑resolution laser scanner, and gives them maneuvering commands by radio. Each of the four wheels is individually driven by a step motor. This allows precise steering, which is important when driving around obstacles and when docking onto the large transport containers. The transport robots operate at walking pace, just under six kilometers per hour.
At today’s level of development, the central computer can control the transport robots in a radius of twelve meters – individually or in trains. To cover a large hall, it would be necessary to have either several laser scanners or a computer with a laser scanner as a mobile unit that drives through the hall, guiding a group of driverless vehicles. In both versions, the new technology is convincing with its flexibility, robustness and precision.
The second driverless technology from Audi’s Technical Center for Production Assistance Systems goes even further: the so‑called Audi AGVs. They use intelligent navigation software developed by Audi on the basis of automotive software and automotive‑software development processes. This means that they can supply goods from the warehouse to the assembly line freely and autonomously. They recognize complicated traffic situations and react to them flexibly.
The navigation system allows an Audi AGV to drive autonomously on a defined route, which is designed and simulated on the computer in advance. Alternatively, the AGV can learn a route on a manually controlled drive and store it. On the basis of this map, it moves freely within its radius – according to the principle of machine learning, it always searches for the optimal route.
The Audi AGV, known internally as “Paula,” has three onboard laser scanners – two at the front and one at the rear. They give it orientation and also make sure that it cannot collide with people. One of the front scanners points upwards so that it can recognize objects hanging from the ceiling.
The sensors also serve to record measuring data – the computer of the AGV then compares that data with its own map data. At the same time, the navigation software compares the data measured by the laser scanners with the wheel revolutions, allowing exact localization.
The driving strategy of the Audi AGV is defensive. It recognizes an employee or an electric vehicle crossing its path and always gives them priority. Its speed is limited to 4.2 kilometers per hour. All braking is gradual and energy efficient. In calculating the braking, the engineers used similar algorithms to those used for controlling the adaptive cruise control (ACC) in Audi cars.
With its laser scanners, the AGV recognizes the workpiece trailer from its contours. It drives up to it to the nearest millimeter, even if it is not standing in its predefined position. Parking over the charging plate takes place with the same precision. A touch display at the front, an extensive visual signal concept and voice output allow communication and interaction with the surroundings.
The navigation development of the AGV at Audi’s Technical Center for Production Assistance Systems has meanwhile reached the third prototype, which is close to the final version. Like its predecessor, it is also a completely independent development by Audi in all areas – including the software. At present, the Audi AGV is undergoing extensive test drives in the Audi A3/Q2 assembly hall at the Ingolstadt plant.
This technology has great potential: Connecting the navigation data of several individual vehicles with a fleet manager creates an intelligent overall system.