At opsira GmbH, innovative goniophotometers are becoming reality using KUKA robotsThe multi-functional “robogonio” light meter:
The multi-functional “robogonio” light meter: That is what opsira GmbH - based in Weingarten, Germany - placed on the market about three years ago. Named by fusing the words “robot” and “goniophotometer” together, the robogonio measures the angle-dependent luminous intensity distribution of a light source or lighting and combines the advantages of industrial robotics with modern light measuring technology. Since 1999, opsira has been a full-service provider for the optics and lighting industry and currently has 16 employees. With “robogonio”, opsira is strengthening the business unit for measurement systems. In doing so, the manufacturer of light measurement systems relies on different KUKA robots of all sizes. This enables exact measurement of even the smallest LEDs, car headlights, traffic signals such as stoplights or railroad crossing signals, through to the airfield lighting fixtures at takeoff and landing runways at airports.
robogonio - a goniophotometer for different types of measurements
In lighting technology, goniophotometers are the standard measurement method and have now been in use for over 100 years. The conventional design comprises the mechanical goniom eter configuration with a horizontal and vertical axis for rotating the test item (e.g. a front headlight of an automobile) as well as a photometer which measures the light intensity. In recent years, the requirements for goniophotometers have increased as systems have become lighting technically more complex and compact and as optical design tools have become more powerful.
While traditional goniophotometers are very limited in their application and require different machines and test methods for near and far fields, the “robogonio” combines the advantages of different conventional goniometer types. The “robogonio” uses the robot’s six axes for the positioning of the test item as well as for angle manipulation that is high precision and reliable. The high number of mechanical degrees of freedom enables measurements in the traditional A, B or even C planes using a measurement system and thus combines goniometer types 1.1, 1.2 and 1.3 into one device according to DIN EN 13032-1. Depending on the configuration, goniometer types 2.x, 3 and 4 are also possible. In concrete terms, the “robogonio” can thus measure luminous intensity and radiant intensity distributions (EULUMDAT, IES, etc.) color distribution or even luminance distribution (glare).
Thanks to the combination of different measurement techniques, reliable data from light sources can be gathered as a basis for the optical design process and all measurements can be carried over to the resulting products such as lamps, headlights or signal lights. “By linking the classic goniophotometer with an industrial robot, we have become significantly more flexible as well as significantly more robust. Beyond that, there is a considerable improvement in accuracy,” explains Jürgen P. Weißhaar, CEO of opsira GmbH, regarding the advantages of the “robogonio”. The robot’s high repeatability and precision are essential for the precise angle positioning of the “robogonio”. This innovative solution has been TÜV certified and the angular accuracy value of 0.005 degrees has been officially confirmed. “That puts us at the top end,” adds Weißhaar.
High scalability thanks to the broad portfolio of KUKA Roboter GmbH
As a result of the decision for KUKA Roboter GmbH, opsira can offer its customers the entire product portfolio. The scalability ranges from solutions with the KR AGILUS small robot series through to the use of KR 6 and KR 30 robot types and onto the medium payload range of the KR QUANTEC series. Solutions with the KR FORTEC or KR 1000 titan product families - which belong to the heavy-duty category - are also possible. This makes the “robogonio”, despite its size, very flexible - ranging from a payload of 6 kilograms with a 700 millimeter reach to a payload of 1,300 kilograms with a 3,000 millimeter reach - so that it can be adjusted to the individual needs of the customer. With payloads of 6 or 10 kilograms, the “robogonio” is the ideal solution for measuring both small light sources such as LEDs as well as small luminaires. In the automotive industry, “robogonios” are used for 90 kilograms or even 120 kilograms, if complex front headlight systems must be measured. Each “robogonio” features exceptional high angle repeatability while simultaneously achieving extremely high measurement velocity.
Innovative solution approach with clear advantages
The innovative solution approach of the robot-based light measurement system was developed jointly with KUKA and offers clear advantages compared to conventional goniophotometers. “Our customers appreciate the wide selection of different goniophotometer sizes as well as the flexible uses for different applications both in near and far-field goniophotometry. The investment thus covers all measurements required for lighting technology - from the light source to the finished lighting,” reports Weißhaar in discussing his experience with the market.
Besides the high number of mechanical degrees of freedom and the associated sampling at different levels, the “robogonio” can be used to warm up the test item in the working position. For this, the light measurement system first holds the test item in its typical working position (e.g. in a position horizontal to the ground). At the start of the measurement, the test item is then automatically rotated into the measurement direction and brought into the first angle position. The “robogonio” is thus ideally suited to meet the new lighting measurement standard EN13032-4.
Even the test methods for measuring the increasingly popular LED linear luminaires (e.g. for ambient or door lighting in automobile interiors) can be carried out with the “robogonio”. It can thus quickly adapt to current market trends and flexibly shape them as well. The “robogonio” is also just as flexible when used in rooms, laboratories or production halls: Its pivot point can be selected anywhere in the room, and it can be installed vertically or horizontally. “The “robogonio” is our product of the future. Thanks to this innovative technology, we can meet current market trends without any problem, remain absolutely competitive in terms of price and offer light source and lighting manufacturers added value in terms of flexibility and accuracy,” notes Weißhaar as he ponders the future.