FEATURE ROBOTICS & MOTION CONTROL


UNCAGING YOUR ROBOT C


ollaborative robots (cobots) are bringing the fences down in


manufacturing and production facilities worldwide. Unlike early industrial robots that had to be isolated behind a protective cage cobots are equipped with sensors, vision and in most cases, programmed self-control, enabling them to work safely side-by-side with people. Compared to its yellow cousins the


Kermit green FANUC CR-35iA is totally cage-free. Designed for tasks like heavy workpiece transfer and parts assembly, it can work alongside humans without a safety fence. A dexterous 6-axis arm with a reach of 1.813 metres, the CR-35iA has a gentler side including a soft green surface to reduce impact force and prevent a human operator being pinched. Certified to meet the requirements of


international standard ISO 10218-1, if it comes in contact with a human or any object with a certain force it stops or retracts immediately. In Japan the robot has demonstrated its higher payload credentials, lifting and putting down a wheel. Thanks to the success of the 35kg payload collaborative robot FANUC will soon introduce the CR-7iA with a payload of 7 kg with mechanics corresponding to that of the company's LR Mate-series. This development represents a


significant leap in addressing robotic safety hazards. Although it doesn’t eliminate the need for comprehensive workplace risk assessments, the increased adoption of peripheral safety devices is enabling robots and humans to work in close proximity of each other, eradicating the fear of interrupting production or worse, causing an accident.


EMBEDDING GREATER CONTROL “Until recently the mindset of most people was if you have a robotic hazard you banish humans from its working area with a physical guarding solution,” explains technical manager Steve Capon. “That thought process is changing for many thanks to rapid advancements in sophisticated software control technology and integrated safety.” This now means that you can impose set limits on how fast your robot works and the operational areas it can and cannot enter, programme it to slow down as it approaches a hazard rather than coming to an abrupt standstill and even introduce presence-sensing detection.


24 SUMMER 2016 | IRISH MANUFACTURING


Collaborative robots (cobots) are removing the fences in manufacturing and production facilities and FANUC has launched one with a payload capacity of up to 35 kg


Above all, the latest robotic software is enabling manufacturers to think more creatively around how automation equipment is deployed and how companies can boost production efficiencies while saving space. “Safety risks vary depending on the


selected robot and application,” says Capon. “One of the key advantages of being able to embed more of the safety- related functions into the robot controller is you can design out the various safety hazards while eliminating the need for external fixtures or mechanical devices to supply this functionality. FANUC recently demonstrated an example of a fenceless robot cell in collaboration with Rockwell Automation. Rockwell safety laser scanners were installed close to floor scanning horizontally for any approach to the system. As an intrusion got closer these scanners informed the robot system to operate slower. Additional mini scanners were concealed under the FANUC robot system mounting, providing an invisible shield and initiating the robot to stop when the box of light is encroached.


SETTING YOUR SAFE LIMITS Many of these developments including FANUC’s Dual Check Safety (DCS) Position & Speed Check solutions were initiated in the automotive sector on FANUC CNC robots. However, the trend for built in logic and safety motion is rapidly spilling into other markets including packaging and palletising. In addition to meeting the safety


requirements for electronic control systems, DCS Speed and Position Check offers significant benefits to applications where the travel of the robot needs to be restricted due to floor space or process


You can design out the safety hazards while eliminating the need for external fixtures or mechanical devices to supply this functionality


limits that are less than the full reach of the robot. Restricting the robot motion in Cartesian space means the robot can be restrained to exactly designated safe area in which it works; something that is not possible with systems that limit robot motion externally using limit switches. In addition, this software works across the whole robot model. For example, Position Check can identify multiple areas including any attached end effectors. The safe zones around the robot arm and its end effector can be modelled within the software using geometric shapes of up to eight vertical lines each. These areas can be adapted, enabled and disabled to change the areas that the robot is not allowed to enter depending on the task it is undertaking and the changing conditions within the defined area. “This is a useful feature for applications that require an operator to load parts into a fixture, for example,” says Capon. “An operator can safely walk into the area because the robot will stop the task it is performing and when the operator leaves the defined area the robot is able to continue.”


The DCS Speed Check functionality


makes it possible to define the maximum speed that the robot can travel during normal operation. Speed can be changed in reaction to a defined event in addition to ensuring that the robot holds a position when necessary. This can be used for zero speed monitoring. “Often there are rotary fixtures within a


cell which must not move while the operator undertakes a loading procedure. The DCS Speed Check functionality allows the speed of the fixture to be monitored and ensures it remains motionless when required. There are process safety benefits to this, for example if the robot is working with delicate products that need to be moved at low speeds.” Ultimately, the onus on safety rests


with humans. Even with technology advancements and comprehensive workforce training you cannot risk becoming risk complacent. Every scenario when interacting with robots should be factored in when conducting regular risk assessments. With safety, getting it mostly right isn’t an option.


Technical manager Steve Capon


FANUC UK T: 02476 518 449 www.fanuc.eu


/ IRISH MANUFACTURING


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