Rise of the cobot
16 October 2016
Suzanne Gill takes a look at the cobot. Finding out how safety can be assured and looking at where this new breed of robot is being employed.
More and more collaborative robots (cobots) are emerging. In contrast to traditional robots, which cannot operate in an operator-occupied workspace without safety fencing, these cage-free robots are designed to work side by side with humans on shared or separate tasks.
“Although collaborative robots do not eliminate the need for 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, an accident,” said Andrew Armstrong, sales and marketing manager at FANUC UK.
Cobots are equipped with force sensing to limit their power and force. In any situation they can feel or detect an abnormal force and stop their motion immediately. Although they still cannot avoid a crash, Cobots can reduce its impact and avoid certain types of incidents, like crushing accidents. This makes them safer to work alongside humans.
In 2013, the first safety standards for collaborative robotics, ANSI/RIA R15.06, were published. More recently, the ISO/TS 15066 standard was published in March 2016 and this specifically outlines guidance for and the requirements of collaborative industrial robot systems, such as contact forces and pressures that can be applied to different regions of the body.
“In order to ensure that humans are not exposed to unacceptable risks when working collaboratively, the current standards describe four separate measures that can be used to provide risk reduction. It is required that at least one of these is fulfilled, in addition to having visual indication that the robot is in collaborative operation,” continued Armstrong. The four measures are:
1. Safety-rated monitored stop: when it is detected that a human has entered the collaborative workspace, the robot should stop. The stop condition should then be maintained until the human leaves the workspace.
2. Hand guiding: the human can guide the robot by hand. Additional requirements for safety include safe-limited speed monitoring and a local emergency stop.
3. Speed and separation monitoring: the robot must maintain a specified separation distance from the human and operate at a pre-determined speed. This measure requires careful risk assessment and needs to take account of safety distances.
4. Power and force limiting by inherent design or control: the power and force of the robot actuators need to be monitored by safety-related control systems to ensure that they are within limits established by a risk assessment.
Ford adopts cobots
The Ford Motor Company is one company that is already adopting cobots for vehicle manufacture.
The robots are being used to help workers fit shock absorbers to Fiesta cars, a task that requires pinpoint accuracy, strength and dexterity. Employees work hand-in-hand with the robots to ensure a perfect fit every time.
The trial at Ford’s assembly plant in Cologne, Germany, is part of the company’s investigations into Industry 4.0. Feedback was sought from more than 1,000 production line workers to identify tasks for which the new robots would be best suited.
“Robots are helping make tasks easier, safer and quicker, complementing our employees with abilities that open up unlimited worlds of production and design for new Ford models,” said Karl Anton, director vehicle operations, Ford of Europe.
Measuring 1m in height the robots work hand-in-hand with the line workers at two work stations. Rather than manipulate a heavy shock absorber and installation tool, workers can now use the robot to lift and automatically position the shock absorber into the wheel arch, before pushing a button to complete installation.
“Working overhead with heavy air-powered tools is a tough job that requires strength, stamina, and accuracy. The robot is a real help,” said Ngali Bongongo, a production worker at Ford’s Cologne plant.
Sensors on the robot will stop it immediately if an arm or even a finger is detected in its path to ensure worker safety. Developed over two years, the robot programme was carried out in close partnership with German robot manufacturer, KUKA Roboter GmbH. Ford is now reviewing further uses for collaborative robots.
Following a Japanese launch for its Du-Aro Collaborative robot late last year, Kawasaki Robotics has more recently introduced the unit to the UK market and it is currently being installed into several operational systems.
Du-Aro is a two arm collaborative robot designed to function as a quickly and easily installed co-worker to meet fluctuating production demands.
Where production runs are limited in volume, justifying costly dedicated assembly or packaging tooling can be difficult. Finding operators to integrate on production lines at short notice, and for limited periods, can be an even bigger problem; so having a co-worker robot that can simply be wheeled into position when needed is a natural progression for manufacturing automation.
Two SCARA configuration arms share the same central pedestal to allow Du-Aro to provide the same working envelope as a human operator. Controlled by a single controller, coordinated arm movements can be programmed easily either by ‘lead through’ or by using a tablet or robot teach pendant.
Low-power motors and speed reduction helps Du-Aro to co-exist with its human operators and in the event of a collision or contact with any object or an operator, collision detection sensors immediately stop all motion.
“The concept of Du-Aro is based around the need for ease of integration and flexibility,” said Ian Hensman, UK sales manager at Kawasaki Robotics. “Integrating it onto a production line conveyor with other operators simply requires it to be wheeled into position and the arms to be physically guided through the required motions. Of course, sensors are required to provide inputs to the controller but even this area has been simplified with the inclusion of optional vision cameras.”
The Du-Aro’s controller can also be supplied with embedded vision processing software. A range of application specific cameras, light sources and grippers can be simply plugged into the robot’s arms.
“We believe we have made the whole process of programming very straightforward from programme routines and sensing, through to simulation of the working area and operation, concluded Hensman.
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