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Vision Guided Robotics Advances - Hardware
Axium Robotics & Automation ULC Posted 06/02/2015
Vision guided robotics – Technological advances that opened the door for vision guided robotics applications in factories – part 2
In part 1 published earlier, we illustrated the advances of vision guided robotics with the evolution of processing time and the development of algorithms and software for vision guided robotics applications. For this second and last part, we will focus on hardware development. To achieve this, we will mainly look at three technologies:
- sheet-of-light triangulation scanners;
- structured light and stereo 3D cameras;
- time-of-flight sensors.
Sheet-of-light triangulation scanners have been known for many years. This approach delivers fast and robust acquisition of accurate and dense cloud of points. To generate the image, a relative motion between the scanner and the part is necessary.
Vision guided robotics applications where accuracy is needed are well suited with this approach. As an example, we can think of quality control of welding surfaces and accurate path adjustments for components assembly.
Recent advances in sheet-of-light triangulation scanners opened many new possibilities for inline inspection and control applications requiring high 3D data density and high speed. The latest CMOS sensors reached a scanning speed up to several thousands of high resolutions 3D profiles per second!
A newer approach for vision guided robotics is based on structured light and stereo 3D cameras. Its main advantage over sheet-of-light triangulation is that it does not need any relative motion between the sensor and the part. This allows fast generation of 3D point clouds with sufficient accuracy for good scene understanding and robot control. The typical rate is 30 fps. This type of hardware is mainly used to perform robot guidance for pick and place or bin picking applications, like the robotic bin picking of rubber bales.
More recently, time-of-flight sensors obtained a lot of airtime. Again, those systems have the capacity of acquiring full depth data frame without any relative motion. Their main advantage is that they can go up to 100 fps, and even more. Because this technology does not require a triangulation base like the two above-mentioned technologies, it is possible to have a very compact design. Time-of-flight sensors have low or no interference with neighboring sensors and offer good robustness to many kinds of object’s reflection properties. Their main drawback is the relative low resolutions (typically 160×120). Recently, some manufacturers announced that mega pixel resolution time-of-flight cameras should be available for 2015.
With this technology, vision guided robotics can now be valuably used in applications like robotic random bin picking, pick and place of random objects without model definition and robot pick to pallet.
In conclusion, the latest advances in vision technologies opened industrial robotics to various new possibilities that were not feasible with “blind” robots. The recent developments in algorithms and sensor technologies make it possible to efficiently implement vision guided robotics tasks for manufacturers. Therefore, we are optimistic that more and more projects will integrate machine vision and robots in the following years.