MACHINE VISION High speed imaging solution with no motion blurring due to better exposure time and sensor precision Motion blurring due to inadequate exposure time High speed imaging for high speed amusement Razor sharp images of objects moving in high speeds are extremely important in industries ranging from food beverage and pharmaceutical to machinery makers. These images provide the engineer the ability to see, analyse and make adjustments to the complicated interactions of various components Apart from the manufacturing industry, they are also important in formula-1 racing events and the roller coaster rides all over the world. Roller coasters and souvenir pictures go hand in hand. For millions of people round the globe, the roller coasters rides are incomplete without a souvenir picture taken of them at the most thrilling point of the ride. With increasing complexities of the rides, the technical challenges in capturing those sharp images also increase. Only a specialist in vision technology can deal with this kind of specialised requirement of high speed imaging system. Shutters: mechanical or electronic Typically cameras with DSLR (Digital Single-Lens Reflex) technology which feature mechanical shutters are used. This system works well and provides satisfactory image solutions but it also comes with some limitations. It has a limited lifetime usually of around 100,000 exposures, before the lens assembly AUTOMATION TECHNOLOGIES 4/2015
MACHINE VISION needs to be replaced. These cameras also have an inadequate frame rate for the faster rides. The alternative to this are the industrial vision cameras which have electronic shutters instead of a mechanical shutter. Exposure time is a very important factor in image capturing. If the exposure times are not appropriate, then for fast rides it means ‘motion blurring’. Short or very short exposure times are needed to avoid this motion blurring for a fast moving scene like a roller coaster ride. Here short exposure time refers to the time required by the object to move by less than 1 pixel on the camera sensor during the exposure. Apart from appropriate exposure time, another important factor is precision. In order to ensure that the exposure of the camera occurs exactly when the object is in the correct position, the camera sensor must be precisely triggered. For precise triggering great care must be taken to assess and reduce all of the factors that can influence delays from initiating a signal to the resultant action in the sensor in order to ensure the required imaged is acquired. In the case of the rides, a number of factors affect the triggering required. These include whether the ride (car) is accelerating or decelerating, how many rows of seats there are in each car that need to be imaged, how many cars will be passing the imaging point and the spacing between the cars. The imaging solution Munich based machine vision specialist Stemmer Imaging was asked to design and supply the complete camera and timing solution, engineered to offer the flexibility to be adapted to individual rides, while Picsolve, an image capture partner for leisure and entertainment industry, took responsibility for the lighting and software. The system consists of a camera head mounted at the appropriate position on the ride, and a base unit containing power, trigger timer controller, opto-isolated trigger input, and network switch. The base unit also provides the trigger out to the lighting unit. The camera head features a high resolution colour camera, lens and lens controller mounted in an IP67 enclosure with integrated heater and screen wiper enabling operation in all weather conditions. The camera provides 5 MP resolution and can operate at 29 Fps in burst mode. Remote focus and aperture control is essential since the camera heads are mounted in difficult locations and need to accommodate changing light conditions. Colour imaging is a complex process which is a function of the illumination method being used and the camera technology. Additional image processing is sometimes required to allow the output image to match the colour quality of DLSR cameras. While the camera used gives excellent colour rendition under the part daylight, part flashlight illumination used on the ride an on-board colour correction capability using a colour recognition and colour calibration tool can deliver corrected colours in all lighting situations. The base unit features an ethernetenabled trigger timing controller which provides very flexible triggering capabilities that can be reconfigured on the fly if required and offers the possibility to programme over 25 timing variations on a single ride. Picsolve software takes control of the trigger timing unit and is programmed for the specific ride to provide the appropriate triggers back to the camera. Fast response and future-proof design Stemmer Imaging has already shipped the first camera and base units to Picsolve for deployment at theme parks across Europe. The project took just two months from initial discussions to prototype units being delivered, with production units following soon after. Since the cameras are generally mounted in locations where access is difficult, the entire camera head is designed for easy interchange and it can be swapped in and out for service and routine maintenance. Apart from the camera’s on-board colour correction capability it also has a number of other features that could be invoked in the future, if required. Firstly it contains on-board memory so if the system is used on rides which require a higher than normal image capture rate, then images can be buffered in the camera before transmission. In addition, jpeg compression is available if needed, depending on data rate constraints on the network back to the paystation. Photographs: Teaser Fotolia, Stemmer Imaging www.stemmer-imaging.com About Company name: Stemmer Imaging GmbH Headquarters: Puchheim, Germany Turnover: € 77 Million Employees: 230 all over Europe Products: Illumination systems, Optics, Industrial cameras, smart cameras and complete imaging accessories and Imaging software ‘Common Vision Blox’ AUTOMATION TECHNOLOGIES 4/2015
