Material handling robots have evolved from traditional two and three-axis “arms.” Common designs of robots and handling systems include articulated robots, parallel kinematics systems, gantry systems and linear axis systems. Precision robotic solutions can fulfill a host of operational requirements for speed, torque, motion sequence, dynamics and positioning accuracy.
Today’s state-of-the-art high-rack warehouse systems feature sophisticated automated storage and retrieval systems (AS/RS), carousel shelving and lift systems with horizontal and vertical axes. Multi-level shelving and shuttle systems, with one shuttle per shelving level, optimize availability and redundancy in consumer goods handling. The output of a shuttle system typically feeds a pallet system, where articulated robots do high speed building of mixed pallet loads.
The size of most warehouse operations does not lend itself to large electrical cabinets, long cable runs and centralized automation topologies. The need for “easy” engineering and commissioning has trended toward decentralized automation topographies. The latest frequency inverters are designed for mounting on the motor or near the motor on the machine, rather than in a cabinet, which drives down assembly costs and cabinet size.
Machine level controller-based, “service-less” solutions are also gaining traction in material handling. Integrated intelligence, safety and communications help bridge an industry-wide knowledge gap as seasoned maintenance people retire. In the past, a single axis system might take several hours to commission. Modular systems with standard interfaces and software modules substantially streamline the engineering process and reduce the time to engineer, commission and maintain drive systems by half or more. Smart devices and virtual IT simplify system monitoring and lower the learning curve for plant personnel.
In next-generation automation controllers, conversion of Cartesian coordinates in a robot’s path of motion to the rotation of individual robot axes can be handled by high performance processors. A controller can communicate with all robotic axes via an Ethernet-based field bus. The programmer can group axes, define motion and create override limits all within the programming environment.
Bridging the gap between synchronized robotic kinematics with miles of single axis conveyance is the key for material handling technologies. Built-in controller software can provide functions to restrict speed and acceleration of each axis—and avoid overburdening machinery or damaging product. Flexible PLC software templates enable the user to integrate standard kinematics. Basic templates can be used to integrate customer and application specific functions. New function modules can be added to templates using IEC 61131 programming language. Function modules created in this way have interfaces which allow them to be easily interconnected with other function modules. The PLC, motion and robotic functions can then run in real time from a single controller.
By 2015, more than 75 percent of roller belt conveyor applications will use a decentralized drive architecture. More than half of roller and belt conveyor applications will communicate via Ethernet. About 90 percent of robotic AS/RS systems will feature safety over Ethernet- based systems. These and other advances translate into higher speed and performance, longer machine life, improved safety functions, programming ease, less maintenance and real energy savings.
Robert Gradischnig is strategic marketing manager for Lenze Americas (www.lenzeamericas.com), providers of motion control technology.