Collaborative Robots in Factory Automation
Published on : Saturday 03-04-2021
The cobot is a revolutionary means for connecting fragmented digitalisation in factory automation, says Jasbir Singh.
The world has gone past three industrial revolutions till time and during each industrial revolution many revolutionary innovations had happened. First industrial revolution, with the invention of the steam engine, which provided the mechanisation; during the second industrial revolution, electric power was invented; and with the third industrial revolution, the innovation came in light was information technology and the Internet. With the present on-going fourth Industrial Revolution – Industry 4.0, innovation is taking place by introduction of digitalisation in Internet of Things and Internet of Services in the manufacturing setup. Industry 4.0 will provide networking of machines in the production line of processes and logistic/networking systems in the global environment. Implementation of Industry 4.0 provides us the digital platform for intelligent machines, intelligent manufacturing and intelligent logistics. In Industry 4.0, the system will exchange information between each connected digital module's production line. The foundation on which Industry 4.0 is being developed by use of Digital Transformation, Robotics, Artificial intelligence, Intelligent Sensors, Machine Automation, Cloud computing, 3D Printing, IoT, RFID, and so on. The implementation of industrial and service robots in production/manufacturing processes create innovations in the process of connecting signals with intelligent sensors.
Autonomous robots/cobots
Cobots are developed and designed to share a facility workspace with humans, making production/manufacturing easier than ever before. Benefits have made cobots a popular choice as it is game-changer for a wide range of applications.
Autonomous production facilities in Industry 4.0 are mainly powered by the use of Internet of Things (IoT), where things are connected with a mesh of objects, sensors and computers and communicate with each other. Autonomous robots are well integrated in these facilities of manufacturing having capability of connecting all related devices by IoT. Autonomous robot connects to the central server, collecting information from its database/taking commands from programmable logic controllers and functioning in a coordinated manner to operate the machines. Robots complete tasks intelligently, using artificial intelligence with minimal human input. Robots are connected digitally with the system, their physical movements/actions are well controlled. Robots either perform autonomously or receive work signals from real-time production system servers and/or manufacturing control systems, assembly devices. By incorporation of robots in operation, line operators can focus on the actual assembly and production line. The induction of robots with humans (Operators) in the production line named Cobot (collaborative robot). Collaborative robot is a robot intended to function for direct human robot interaction within a shared space, or where humans and robots are in close proximity. Cobot integrated autonomous systems primarily facilitate the command and control communication between automated equipment, digitally controlled tools and sensors guided by PLCs, and autonomous mobile robots.
Major features
The intelligence within collaborative robots is to support/perform tasks with humans during operation and adapt flexible tasks to meet new requirements. Manufacturers employ collaborative robots to reap benefits of safety features incorporated in robots that allow them to work with humans and improve productivity for a variety of similar/repetitive tasks. Cobots have numerous in-built safety features such as lightweight frames, collision detection sensors, minimised pinch points, including the gripper, end effector, and other equipment locator near the collaborative workspace. For safe implementation, the design based on risk assessments is the crucial component for success of using a collaborative robot. Collaborative robots are designed to work with human operators using low-inertia servo motors, elastic actuators, force feedback, and collision detection technologies that control its power and force capabilities to levels suitable for contact.
Factors consideration during design
Speed and force monitoring are the two deterministic characteristic abilities of good collaborative robots. Cobots are equipped with safety features that detect when a human has entered into the collaborative workspace to optimise speed/stop else while they are allowed/configured to operate at much higher speeds. These are allowed to operate at a speed to maximise throughput, when people are not present within the defined hazardous zone.
TS 15066 defines the force and speed of the Cobot, which is set based on possible human contact area and workspace hazards. Both types of possible human transient and quasi-static create a different risk level. The transient contact is mainly non-clamping, whereas the quasi-static involves a situation which can cause a body part to be clamped.
Applications in operation, possible human contact, and workspace safety hazards are all factors considered calculating the safety settings as per TS 15066. The safety standard given ISO 10218 and technical specification TS 15066 collectively defines the safety functions and overall performance of the collaborative robot to achieve high productivity. These settings are often changed by improving the safety settings to optimise performance of the overall collaborative application. A great degree of skill is needed to make a better setting by experts who are familiar with safety standards.
Companies employ intuitive hand-guiding mechanisms for teaching new tasks to robots without configuring the logic program for the movements of the robotic arm. Hand-guiding mode of training also monitors set level of force and speed to ensure the teaching process complies with high safety standards as defined in ISO 10218.
The teaching mode selection can be activated by the operator any time by using a simple device or operating a switching mode switch as long as safety of force and speed monitoring systems are active. Safety standards enforce that the teaching mode transition to be deliberate, and not lead to generate unexpected motion, to avoid creating additional hazards.
Hand-guided teaching safety standards
Two major factors are considered while hand teaching:
A. Safe teaching
B. Safe operation
A safe teaching process operator is responsible for the robot’s motion while learning and must be aware of surrounding equipment and their safety concerns by activating space and soft axis limits functions.
During safe operation the operator must vacate the safeguarded space first. This can be realised by light beam barrier/safety sensors or by operator verification. To re-enable the robot for operation, the function of intentional mode selection must be provided/activated for space and soft axis limits.
Collaborative workspace
Cobots perform automated defined tasks with and around other equipment that could potentially cause harm. The area which is meant for a collaborative robot to operate, including tooling or other associated equipment, is known as the collaborative workspace. How the space within the safeguarded area, where the robot and human need to perform tasks simultaneously during production/operations, is defined in ISO 10218/ANSI RIA 15.06. TS15066 on the other hand, defines the area within the operating space, where the robot performs tasks concurrently with a human operator during production. Manufacturers should ensure that evaluation of each device can cause potential hazards and where safety sensors can be used to prevent human and neighbouring equipment damage and the collaborative workspace must be clearly marked. Safety devices are easy to integrate with a collaborative robotic application.
Safeguarding collaborative workspace:
a. Open area safety
b. Gated/limited area safety
c. Active hazards safety
d. Safe robot enable
e. Safe hand
f. Safe operation
g. Safety validation.
Safety area barriers – like scanners and mats are the most popular safeguarding devices for a cobot’s collaborative workspace.
Gated/limited system – where safety light curtains and safety switches are widely used for hazardous applications/high-speed operational area enables for increased safety and productivity.
Active hazards safety guarding – when an operation could cause a hazard, the operator can enable the ‘deadman’ switch for his safety.
Safe robot enable – While starting up the robot for the first time or its recovering from an emergency stop, some revalidation required to enable the robot that ensures operators are safe and no functional hazards are present.
Safe hand guiding – During design and safety setup, operators must ensure that hand-guiding can only occur after, a. the robot has emergency stopped; b. intentional mode selection has occurred; and c. speed and force monitoring devices are activated. Hand-guiding activation without a stop command or safety input, a safety stop and fault should generate.
Safe operation mode – Automatic or run operation command for the cobot by an international mode selection used by the operator must ensure that all safety devices and conditions are validated for operation. This is done automatically also.
Safety validation – Safety experts should perform an on-site inspection to assess the safety of equipment, confirm certifications, verify safety parameter settings, and document that ensures safety validation has been completed and compiled.
Machine tending is most important with use of cobots due to the ease of its installation, to get the high RoI, and reaping the benefits from its flexible manufacturing capabilities of high speed robots.
Other major/important factors in consideration:
1. Some of the machines need to be safety control-linked to prevent from operating, when some other is in a safety stop condition?
2. Is material handling equipment simultaneously being used? If so, what are the critical safety considerations?
3. Since cobots used in the machine tending, can be moved from machine to machine, what are the safety settings and program validation system?
4. Are warning zones for the operator given which will indicate hazards or operation interference?
Summary
Cobots are normally designed to work with human collaborators in mind, and are safe; however, it still requires risk assessments to guarantee safety of operators/surrounding equipment throughout their use. It is crucial for users to consider every possible hazard associated during hand-guided teaching, transient and quasi-static contact, as well as when the robot is in an emergency stop condition.
Jasbir Singh is an Automation Expert having long experience in Factory Automation, Line Automation, Implementation Strategist, Business Coach, Regular writer on automation, Artificial Intelligence, Robots/Cobots, Digital Technology, Network Communication, Industrial Internet of Things (IIoT), Wireless Communication, Block Chain and use of advance digital technologies. He has established a long association with Business Houses/large production houses to improve factory automation in their production lines as well as productivity improvement in factories in India and overseas; and in advising and designing the units to transform into digital platforms by use of Artificial Intelligence. Email: [email protected]
