As more manufacturing facilities and distribution centers discover the benefits of robotic material handling solutions, the decision of how best to control the robot must be made. While robot original equipment manufacturers (OEMs) offer their own tightly integrated controller, recent developments have enabled control by a Programmable Logic Controller, or PLC. For facilities where PLC-based controls are already used in other machine control applications, the benefits of using one for the robot as well may be a wiser choice than the OEM controller. Let’s review PLC-based robotic control to help you determine if it’s the best choice for your application.
Speaking Robot Just Got Easier, and Training Time Shorter
If you’re familiar with PLCs, as many engineers and technicians are, then you know how to read, understand, and troubleshoot a PLC-based robot. What the robot should be doing and how it should be doing it are still required knowledge, but the hurdle of learning a proprietary OEM control language disappears, and with it much of the training time previously required. Moving to the PLC-based robotic controls world brings additional advantages, including:
- Common programming controls (software, cables, etc.),
- Common software interfaces,
- Common program backup/restore methodology, and
- Common program documentation.
Interfacing with the Robot Controller is Greatly Simplified
Robotic material handling solutions are comprised of complex systems, including many different types of equipment in addition to the robot(s). These systems generally include components such as infeed conveyors, discharge conveyors, pallet dispensers, transfer cars, and other additional equipment. System components are typically controlled via a PLC; therefore, the robotic controllers must interface to the system controller, handshaking data and interlocks to achieve the desired functionality. Depending on the complexity of the application, this interface can be quite challenging.
“As we studied the packaging and palletizing markets, we recognized the need for a unified control strategy,” said Steve Barhorst, president and chief operating officer, Yaskawa America, Inc., Motoman Robotics Division. “These markets have engineers and technicians with extensive experience and expertise with PLC controls and programming. We view the development of this strategy as an easy way for these users to adopt robotics into their packaging lines without the burden of having to learn a new robot programming language. Users now gain the flexibility that robots offer in a PLC-based platform they already understand. We still offer our standard robot controller, the DX100, for applications requiring process control like welding, dispensing, and painting.”
When the PLC that controls the robot is the same PLC that controls the other system components, it eliminates this interface point and greatly reduces the overall complexity of the solution. “One controller can now handle process, safety, and robot control, with the same hardware and software platform. Robotic solutions can reduce integration and development costs for machine builders, and reduce end user lifecycle costs with a common hardware and software platform,” confirmed Robert Weeks, global business development manager, North American Material Handling OEM Business, Rockwell Automation.
Common Controls Architecture
The controls hardware design for a PLC-based robotic controller can now utilize a common controls architecture with the system controls. “KUKA Robotics worked with Rockwell Automation to develop the capability to control select KUKA 4-axis robots to address demands from consumer packaged goods end customers who were looking for a single integrated control solution for their packaging machines and robotics,” said James Cooper, vice president of sales and marketing, KUKA Robotics Corporation. “Additionally, they have requested a single point of operator interface for their automation solutions that involves traditional packaging machinery and robotics.” In addition to reducing overall footprint by being housed in the same control panel(s), the design of the robot controls uses the same drawing nomenclature (wire number, drawing numbers, etc.) as all the other hardware in the panel, reducing the overall complexity of the control system design. Benefits can include:
- Simplified troubleshooting and maintenance
- Reduced panel footprint
- Simplified training
- Common spare parts
- Common wire number/drawing numbering
- Common part numbering scheme