size operations. One representative example is the KUKA Robotics AGILUS family, which has three versions. The AGILUS KR 3 R540, mentioned earlier, is the smallest. It operates within a two foot square footprint and can handle loads of up to 3 kilograms (kg), making it suitable for numerous assembly and materials handling applications. The AGILUS KR 6 R900-2 handles up to 6 kg and the AGILUS KR 10 R1100-2 up to 10 kg. All three have the same overall form and behavior and are available in kits, complete with a controller unit and handheld operator unit for controlling, monitoring, and programming the robot's activity. The mechanical design of the AGILUS devices gives insight into the flexibility of robotic arms in general (Figure 3).
Figure 4: Robotic arms can position the center of their wrist within a vertical region (a) oriented nearly anywhere around the robot's location (b). (Image source: KUKA Robotics Corp., modified by DigiKey)
Like many robotic arms, the AGILUS devices have six
skills, but that has now been simplified. Robotic arms typically come with a controller computer and a user interface tablet that allows a user to move the robot using simple directional buttons to reach desired "waypoints." Logging a series of waypoints defines the complete sequence of motions the robot can follow automatically. Some robotic systems also allow the user to manually position the robot arm to desired waypoints instead of using the directional buttons. Both approaches serve to "teach" the robot by example what movements it is to execute, which it will then be able to repeat upon command. The ability for the user to teach rather than code not only simplifies initial robot setup for a task, it allows for easy adaptation of movement as requirements
movement axes: a rotating base (A1), a base arm (A2), a link arm (A3), an in-line wrist that can rotate (A4) and bend (A5), and a rotating mounting flange (A6) where end- effector devices are attached. Axes A2 to A5 work together to position the center of the wrist anywhere within the vertical operating profile, shown in Figure 4(a), while the rotating base can direct that vertical profile almost anywhere around the arm (Figure 4(b)). The center of mass for the end effector attachment can be offset from this position, as shown. The arm can be mounted on a floor, bench, cart, wall, or ceiling as desired without impeding operation. Controlling a robot's movement with all these axes used to require sophisticated programming
Figure 3: Six axes of motion provide flexibility in the mounting and reach of compact industrial robotic arms. (Image source: KUKA Robotics Corp.)
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