Application Note | Case Study | Technology Primer | White Paper How to Apply Machine Vision to Automate Inspection Tasks Replacing human vision with machine vision in inspection tasks can reduce cost and improve product quality. Human vision is unreliable when used for high-speed, precise, or repetitive inspections. Machine vision systems have three general capabilities: 1. Location or search finds the position of the object of interest. 2. Identification tells you the type of part. 3. Inspection checks that the object has the proper dimensions, meets quality standards, is free of specific defects, etc. First, ask if your task can be done by machine vision. Vision tasks that require a lot of “real world” knowledge or have parts that have large variations can be difficult to automate. For example, we find cracks in a textured, glass part using our knowledge of what cracks look like and moving the part so it is “just right” to see cracks. This is not easy for a machine vision system. Machine vision is best used when the parts have known shapes and where defects have limited variation and are clearly visible. Next, ask what type of vision system is appropriate. Some simple inspection tasks can be done by a “vision sensor” that does one kind of measurement, such as measuring the depth of a hole in the part. Most machine vision tasks require a machine vision system with these components: - Motion control to bring the part into the camera’s field of view - A sensor to detect when a part is in the camera’s field of view - Special lighting and a way to reduce stray light - A machine vision camera and lens - A vision processor – a computer specialized for machine vision - Vision processing and control software Figure 1 - Diagram of a pill inspection system The vision processor has to be programmed for the vision task. Until recently, this was often a difficult and time-consuming task. DALSA IPD’s focus is on easy-to-use machine vision software that can quickly solve your vision inspection task. For example, in our iNspect™ software, vision operations are presented in familiar terms, such as “calipers”, and an intuitive user interface guides you through the set-up of your vision task, without requiring programming. Figure 2 shows the iNspect user interface for the blister pack inspection system. DALSA IPD provides cameras, vision processors and vision software, and recommends other components. Our partners include automation distributors who supply and integrate all the components into machine vision systems. Figure 1 shows how these components are combined to make a machine vision system that checks for broken or missing pills in a blister pack card. A conveyer belt moves a card into the camera’s field of view. Diffuse lighting reduces highlights from the plastic covering the pills. A vision sensor detects when the card is in position and triggers a VA30 Vision Appliance™ to take an image of the card and process it to detect broken or missing pills. The VA30 is one of DALSA IPD’s compact vision processors. The VA30 and vision software locates each pill and identifies defective pills by inspecting the pills’ areas, perimeters and intensities. Inspection and identification results are displayed for monitoring by an operator. When a card with defective pills is found, the VA30 sends a signal to a rejection mechanism that removes the card from the product stream. Figure 2 - iNspect’s operator’s screen when doing blister pack inspection With DALSA IPD’s cameras, vision processors, software and, of course, support, you can quickly apply machine vision to automate inspection tasks. 700 Technology Park Drive, Billerica, MA 01821 USA Tel: +1 978.670.2002 Fax: +1 978.670.2010 Email: [email protected] www.goipd.com DALSA is an international leader in digital imaging and semiconductors and has its corporate offices in Waterloo, Ontario, Canada. All trademarks are registered by their respective companies. DALSA reserves the right to make changes at any time without notice. ® DALSA 2010. 031010_wp_mv_inspection