Robots have been a force in the increase in flexible automation for many years, but until recently robot vision was limited. Previously, a vision system would have required a PC with a custom frame grabber to “grab” images from cameras in addition to custom and oftentimes highly complex software to analyze the images. These systems usually required vision experts, which either had to be brought in or added to staffs to maintain the systems and to create the sophisticated algorithms necessary for image analysis. This was, and continues to be, very expensive when done this way.

No Longer a Work of Art

Today, this is no longer true—things have changed drastically. These systems were previously “works of art,” requiring integrators to be on-call to tend and tweak the system. Currently, with new cameras being implemented, it is becoming more and more of a science. Cost-effective vision systems are readily available, with greater accuracy and a much wider range of capabilities than earlier systems. With more user-friendly software, manufacturing engineers can make product changes (without the need of a vision expert), adjust tools and create new inspections. Vision guided robotic (VGR) systems now represent a true value for manufacturers and end users, because the tools have improved while the total cost of implementing the systems has dropped to a much more attainable position. The amount of data that these systems can provide and the rate it can be shared has increased in amount and ease mostly because of the proliferation of the use of Ethernet communications. Robot manufacturers have added Ethernet connections to allow robots to communicate quickly with other robots and any other device that is on the factory network. Robot controllers are adding more built-in I/O modules and communications options with programmable logic, allowing them to control peripheral devices. This makes using a PLC or PC as the main controller optional.

Automation used to mean large batch runs and limited options and flexibility. Companies are trying to optimize the use of space and reduce the time it takes to perform changeovers when running multiple products on the same line. The use of vision guided robotics allows companies to make multiple products in a faster, more efficient manner. The cost savings is seen in reducing the number of spare components, fixturing of parts, and more importantly, increased uptime and use of machines in manufacturing multiple products. Instead of having to build a completely new line, write a new program and possibly design a new end effector, which can change the entire function of the system, a vision guided robot can be set to work with multiple products from the beginning. This makes VGR systems more viable than ever before.

Lighting Considerations

Of course, even with today’s user-friendly vision technology, setting up a new system can still be challenging. For example, lighting in machine vision applications is still more art than science. Lighting trials done in labs rarely duplicate production environments. Moving parts, factory lighting, environmental pollutants (dust, smoke, mist) or outside windows and skylights can adversely affect the performance of many vision applications. Engineers must ensure that once the lighting has been resolved, factory conditions will not affect a new system after installation.

Any system in which a robot gets data from a camera, no matter the goal of the system—whether it be a six-axis robot picking parts from a bin or an automated guided vehicle (AGV) moving product around a warehouse—is a form of vision guided robotics. It is a fast growing technology and a way to reduce manpower and retain production, especially in countries with high manufacturing overhead and labor costs.

New Applications and Advantages for VGR

Much in the same way that the nearly full adoption of vision-guided robots has helped automate the production of automobiles by making the assembly of vehicles more consistent and much safer, the growing acceptance of VGR in the food and beverage market will soon change the way these products are brought to market.

The advantages of implementing robotic systems can make a vast improvement in the productivity and overall profitability of a facility. Yet by adding vision (in 2-D, 2.5-D or 3-D) the amazing potential in industrial robotics to create a system that is cutting edge in precision, intelligence and effectiveness is leveraged to whole new level. Adding guidance can enhance the capability of robots performing any type of application, from machine tending to bin picking to welding.

When guided by vision systems, a lot of guesswork is removed from a robotics application. For example, with a robot cell without guidance, parts need to enter at an exact orientation so that the robot can then correctly handle it. Meeting this requirement could be quite costly when done back-stream and could create stresses or bottlenecks in the overall production process. With VGR in the same application, the robot can see the skew and alter its angle to execute the process perfectly. 

VGR systems can also provide flexibility that is essential when dealing with unknown part sizes or different parts entirely that may be produced or sorted on the same production line. A system that is employing a vision system can also be used to archive and store data for improving the performance of the system over time. 

The list of possible applications that can benefit from vision guidance is an incredibly long one. The type of robot and type of vision inspection implemented in these applications can vary wildly. The robot can be as simple as a revolving door or as complicated as a group of multi-axis robots working in unison to build complex and intricate circuits, just as the camera systems involved can vary from simple vision sensors to multi-camera 3-D systems that inspect entire assemblies and compare them to customer CAD data. V&S

Jim Anderson is SICK’s national vision product manager. For more information, call (800) 325-7425, email [email protected] or visit www.sickusa.com

TECH TIPS

Automation previously meant large batch runs and limited options and flexibility.

Today companies are trying to optimize the use of space and reduce the time it takes to perform changeovers.

The use of vision guided robotics allows companies to make multiple products in a faster, more efficient manner.