Robotic Arm—Where Humans Lose to Machines?
Human bodies are fragile, grow tired and get sick. Each has its own limits, of course—some are tougher, others are weaker, but no person can work twenty-four/seven without losing concentration or getting out of time. The total of the above and similar factors slow down production, entailing extra costs, such as compensations for labour accidents, and degrading competitiveness. Therefore, enterprises aim at automating their manufacturing processes by replacing people with industrial robots or robotic arms.
The available variety
A robotic arm is a set of rigid structural elements capable of taking various configurations and shifting from one configuration to another with predetermined speed and acceleration. The individual structural elements are links, and the actuation hubs between the links—joints incorporating servo motors or other engines. Arms can differ by size, number of freedom degrees (DOF), workspace, etc. The general classification is as follows:
- Cartesian or gantry robotic arms have three control axes corresponding to the number of joints. The joints are attached to guide rails enabling their displacement in accordance with the Cartesian coordinate system. Motion is not rotational, rather—along a straight-line trajectory. Such structures are designed for pick-and-place, assembly lines, arc welding, and sealing.
- Cylindrical manipulators have a cylinder-shaped envelope. Similarly to the Gantry-type solutions, the mechanisms feature three movement axes—two of them are linear, whereas the third one is rotary. Mostly, the devices are employed in spot welding, machine tending, and assembling.
- Polar, or spherical, robotic solutions provide rotation to a spherical pattern relying on the polar coordinate system. The mechanisms are widely used in different welding operations, as well as to tend to industrial machinery, such as die casting or fettling. Modern industrial robots utilize a similar positioning approach.
- Articulated manipulators can comprise from two up to ten or more rotary joints. With the extensive number of axes, the articulated construction provides more versatile motion and is designed to perform complex drilling, welding, or material handling tasks.
- Parallel, or delta, arms incorporate several multi-joint parallelogram structures enabling moves within a hemisphere. Boasting accuracy superior to solutions of serial configuration, deltas are a perfect choice to support pick-and-place manipulations.
- SCARA solutions, otherwise Selective Compliance Assembly Robotic Arm, have a two-link configuration with two joint—an elbow and a shoulder—rotating in parallel. Because of the peculiar axes arrangement, the mechanism is pliant along the X-Z paths and non-compliant along the Y axis. SCARAs are a good pick, if you search a solution to automate cargo handling, assemblage, or machining. They boast swifter response than Cartesians and feature a space-saving footprint.
Some sources also distinguish anthropomorphic arms. The name is due to the mechanism resembling a human hand anatomically, with fingers, thumbs, and fine motor skills. Collaborative robots, or cobots, make a separate class of robotic systems. Cobots incorporate enhanced safety features (e.g., monitored stop) and special capabilities (e.g., hand-guiding) enabling people and machines share the same functional area.
Essential robotic arm parameters
The way robotic vendors configure their model ranges based on the following characteristics has a major impact on their suitability for certain purposes.
Number of control axes
The more numerous axes are, the wider range of motion an arm is able to cover. The parameter correlates with available DOFs, defining the overall positioning capability of a robotic arm. With seven DOFs, a machine provides the same dexterity as a human limb.
The envelope is a 3D shape of a particular form describing geometrically the motion range of an arm, including forward, back, up and down directions. The form is in accordance with the types outlined in the previous section—either a sphere, a hemisphere, or a cylinder, etc.
It is an area adjacent to the footprint where an arm can operate without restrictions. Stationary installations have a fixed envelope and workspace, whereas mobile or so-called flexible robotic devices can vary both parameters.
Speed is the linear displacement rate in meters per second measured at tool center point (i.e., where the tool is attached to the manipulator body). An important related parameter is acceleration affecting the final velocity of the arm at specific distances.
Accuracy and repeatability
The parameters define the ability of an arm to complete a task in exact time and with desired output within a single try and to repeat the same task over multiple attempts with the same result, accordingly.
Payload is how much a manipulator can handle, factoring in required movement trajectories. The value includes both the mass of the robot proper and the weight of the tool and the load.
The parameter describes how governance of motion is implemented in a particular mechanism, including the technology stack and add-on hardware, such as computer vision or sensors.
Robot vs. human labour
In the argument whether it is worth spending money on modernizing a production facility with robotic arms, the key “pro” reasons are as follows:
- Optimized productivity
When introduced to automate previously manual operations (e.g., palletizing), a robotic arm enables to cut operational cycles and re-distribute resources. Whereas people get tired and distracted, smart machines are rugged enough to remain functional around the clock, while delivering unvarying output. Substituting a worker on a production line for a manipulator is claimed to raise production capacity by 40%—and that’s only due to the arm’s ability to run non-stop.
- Improved production quality
It is unavoidable that our mind would wander off as soon as we start feeling weary. In contrast, robotic systems are always on guard, attentive to minor details, with its accuracy of movements remaining unaffected over numerous repetitions. Whereas a person's arm might tremble or fail suddenly, robots have near-zero mistake or failure rates, resulting in improved quality of products.
- Safe workflow
Working in a hazardous environment, such as in a compartment with dangerous gas content, means endangering life, even with protective gear on. Performing repetitive manual operations over extended periods is also a health risk leading to strain injuries. Replacing people at these jobs curbs associated risks, making operating environments more friendly overall.
The benefits of improved efficiency, production quality, and safety translate into decreased manufacturing damages. Reduced time and resource consumption, no labour compensations to pay in case of on-the-job injuries, fewer rejects, around-the-clock productivity—and profitability is sure to increase.
The PULSE lineup
The robotic lineup by Rozum Robotics includes two models—PULSE 75 and PULSE 90, both featuring 6 degrees of freedom. With linear velocity of 2 m/sec and repeatability of +/-0.1, the products cater to industrial applications demanding superior precision of positioning and unfailingly high performance. The payload capacity is 4 and 5.5 kilograms, and the operating range is 750 mm and 900 mm accordingly.
Lightweight and compact, the robotic arms allow various integration opportunities, even when available floorspace is restricted. Control is either via graphical interface for unskilled users or via C-, Java-, or Python-based Application Programming Interface when advanced setup is needed. The total of features providing governance of movements and secure functioning are implemented in a detached module—control box.
PULSE cobots provide the benefits of production rate and quality optimization, cutting expenses related to manufacturing defects and inefficient workforce. Plus the ability to cooperate with people without the need to lock them behind protective fencing. Teaching trajectories by hand guiding makes setup and adjustments quick and easy. Robust construction and servo actuators with the lifetime of 35,000 hours, non-stop, guarantee extended reliability of the products.
Enjoy being on the cutting edge of productivity with PULSE cobot! Order the smart machine online or contact us by email or phone to get more data about price policy and contract terms.