For machinery OEMs interested in modular machine design, increased levels of performance, flexibility and smaller footprint machines, motion and automation control technology continues to offer compelling solutions.
Even as manufacturing has advanced and machinery has become more sophisticated, Ethernet-based control, robotics and integrated motor-drive solutions are continuing to keep pace. New machine designs are leveraging these technologies in unique ways to meet specific goals and improve machine performance. Here is a series of state-of-the-art automation and motion control applications that illustrate how these new technologies are helping to drive higher levels of machine control performance.
Major Strides in Rehabilitation Therapy
Motion technology enhances physical therapy while reducing therapist labor up to 75 percent.
Consistent motion gives patients the ability to walk more than a thousand feet and take several hundred steps in one session.
Losing the natural ability to walk can be characteristic of injuries or illnesses such as stroke, brain injury, Parkinson's disease or Multiple Sclerosis. HealthSouth Corp., a leading company in the inpatient rehabilitation market, has developed a safe and efficient rehabilitation tool incorporating Rockwell Automation motion control. It allows hospitals to treat more patients, more efficiently and offers the highest standard in rehabilitation therapy.
Most physical therapy for individuals who have lost use of their legs requires up to four therapists to simultaneously support the patient and move the patient's legs. Seeking a therapy tool that would alleviate the physical stress for the therapists, HealthSouth's engineering team addressed these concerns by designing the AutoAmbulator which employs a harness to hold a patient in an upright position while robotic braces move the patient's legs across a treadmill.
The first few prototypes of the system were designed with the motion control independent from the central machine controller which hindered communication, programmability and flexibility and didn't allow for smooth, controlled movement. A new system using Allen-Bradley® Kinetix® motion provides a complete automation system consisting of ControlLogix® programmable controllers, servo drives, servo motors and actuators.
The AutoAmbulator is built on an assembly line with the first stage being the basic frame setup including the treadmill, control panel, wiring and other components. An RSView® 32 HMI allows engineers to replace custom-written codes with standard programming that is more flexible, scalable and allows for development of a comprehensive database of information to track patient outcomes.
The AutoAmbulator design includes controlled, synchronized robotic legs that allow patients to use normal gait patterns and participate in the movement, but rely on the system for the remaining force necessary to generate the motion. Sensors track the AutoAmbulator functions, continuously monitoring and adjusting power and speed according to each patient's unique condition. The machine design also allows therapists to adjust the weight bearing and walking speed to meet each patient's individual rehabilitation plan.
To minimize risk of injury, the AutoAmbulator includes safety features that automatically stop the machine for events such as a severe spasm or if the patient's foot improperly strikes the treadmill. These features are enabled by photoelectric sensors that monitor torque through the motors and gearboxes to ensure the patient's legs don't experience excessive force.
The AutoAmbulator and automation controls all are connected to a VPN network and provide advanced feedback and diagnostic capabilities.
“If there is an issue with one of our machines, we can go online and diagnose it without having to make an on-site visit like we had to with the old system,” says Derick Puckett, an electrical engineer previously with HealthSouth and currently with Motorika USA, a company that specializes in rehabilitation robotics. “With this method, we have an off-site repair success rate of more than 75 percent.”
The objective of gait training is to re-establish a natural walking pattern. A typical 30-min gait training therapy session using the traditional method might produce 50 to 100 steps, but doesn't give the patient's brain practice with leg movement that is natural and consistent. The AutoAmbulator system reduces the patients' fear that stems from instability and allows consistent motion to walk more than a thousand feet and take hundreds of steps in one session.
Another benefit is one therapist can give a patient a more intense and consistent therapy session. By reducing the staff required to perform this therapy by 75 percent, HealthSouth expects to see an improvement in staff utilization. Since 2003, 93 AutoAmbulators have been installed at HealthSouth rehabilitation hospitals, increasing patient capacity with the ability to facilitate more than 70,000 inpatient sessions.
Ethernet-Powerlink simplifies tube-bending cell
Ethernet-compatible Powerlink motion and machine control hardware is at the heart of an innovative automatic cell for manufacturing tubular automotive parts. The Powerlink system controls four axes of motion, I/O and contributes to both the rapid development of the cell and its exceptionally small footprint.
Called Uni-vercell, Unison's machine packs a complete end-to-end, loading/end-forming/bending and vision inspection process in the space typically required for a stand-alone tube-bending machine. The new design also exploits an articulated robot arm to manage all the intervening movements and transfers. The arm eliminates the need for the conventional carriage of a tube-bending machine and optimizes manufacturing precision because it retains the part for the duration of the process, eliminating hardware in the process.
The tube-bending and end-forming processes are handled by a NextMove e100 machine controller from Baldor. This controller manages four MicroFlex e100 servo motor drives that control the tube-bending head's clamp, pressure die and bend arm axes plus the actuation of the end-forming tool for flaring and/or compressing. The controller manages all of the cell's I/O, plus the link to a front-end user interface.
Unison says the daisy-chained nature of the Powerlink network reduced the electrical system's size by up to 50 percent compared to analog motion control solutions. The speed of the 100 Mbits/sec Powerlink network provided bandwidth to dynamically control each motor's position and torque parameters and offer a simple means of gaining ultra-precise control over the bending process.
A key design goal was system expansion and evolution because the cell is designed for repetitive production of mass volume parts such as automotive fuel, water or hydraulic components. There is no front-end user interface on the system and the bill of materials resides on a laptop connected as required to the cell's NextMove e100 controller, to download production programs. But Unison also designed the cell concept to appeal to general metalworking fabrication companies who manufacture in smaller batches and for this application it's likely a local human-machine interface will be required.
Using a standard Powerlink gateway device, the cell can be easily connected to a PC or conventional Ethernet network. Another expansion possibility is more motion control axes, for more complex end forming, labeling or marking.
Using Baldor's Mint machine control development environment and its suite of programming development tools, Unison wrote the software for the entire cell in just two weeks. This included the interface to the PC front-end, which was simplified thanks to the free availability of ActiveX tools, making it very easy to create a Windows-based PC application that communicates with the cell controller via USB.
“For this machine, I managed to program the first iteration produced in just two weeks, which speaks volumes about the simplicity of the control system and the development tools,” says Mike Kay, Unison's lead engineer on the project.
The Uni-vercell can fabricate parts to an overall accuracy of 0.1 mm. Although the cell is optimized for repetitive volume applications, the flexibility of the robot arm allows it to be configured easily for batch production, as well. Drift-free performance means the machine can be instantly set up to fabricate parts just by loading a program, rather than making and scrapping trial parts until the configuration is right.
The software-controlled nature of the machine delivers much greater control over the bending process. Fine adjustments to torque levels or movement profiles can optimize bend quality. Complicated shapes that might be difficult to make on a conventional hydraulic machine can also be produced easily, because the machine is able to make intervening adjustments or moves between stages. This programmability optimizes cycle times by making only the minimum movements required.
Modular Design Uses Integrated Motor-Drive
Modular machine concepts and decentralized controls offer technology solutions for packaging machinery OEMs constantly seeking ways to improve machines to meet the demands of rapid product changeover. Machine flexibility is vital for product manufacturers driving to economically meet the packaging requirements of modern consumer products.
The next step in machinery development for KHS, a leading provider of filling and packaging technology with headquarters in Dortmund, Germany, is using decentralized servo drive technology to help achieve modular machine goals. KHS has already been an innovator in this area, using combinable mechatronics modules to flexibly and economically meet its customers' growing needs for versatile packaging machinery.
But now KHS is installing new integrated motor and drive technology from Bosch Rexroth in its Innopack Kisters SP machine used to shrink-wrap wine bottles. The SP series machines are used in the manufacturing of foil multi-packs for sturdy products and provide a complete power range and continuous operation from 35 to 150 cycles per min. The machines handle cans, jars and bottles, as well as pre-packaged products in the beer, soft drink, hygiene, food and non-food industries.
The advantage of using the IndraDrive Mi integrated motor-drive is KHS can combine different machine modules with greater flexibility according to customer needs. For example, with the addition of two extra machine modules, a shrink packer now becomes a tray shrink packer. Two drives are added to the existing seven, but the change requires no changes in the control cabinet.
“With the use of integrated motor-drive, the system costs are significantly reduced, especially in the required installation effort for the control cabinet and wiring,” says Dirk Langanki, manager of electrical construction and development at the KHS Competence Center for Packaging Technology.
The package combines a traditional servo motor and drive amplifier into a compact but highly functional drive unit. The motor housing surface serves as a heat sink for the drive's control electronics, which are mounted flat on top of the motor without significantly changing the motor's shape. The design reduces the size volume by more than 50 percent compared to traditional servo drives consisting of a separate motor and converter and drastically cuts down the required space and power loss in the control cabinet.
The need for cable connections is also significantly reduced. Only a single cable is needed for both power supply and communication via a SERCOS interface. Up to 20 motor-drives can be connected without additional distribution boxes or modifications in the cabinet. More than one string of drives can be connected in parallel to a single supply unit. By connecting multiple units in sequence, the number of required cable connections is further reduced. More importantly, drives can be added flexibly as needed, without requiring any changes to the control cabinet.
The integrated motor-drive technology has proven itself to KHS through extensive testing. The company recently delivered its first machine to an end-user in the beverage industry and the company plans to convert to integrated motor-drives for all machines in the series and implement the new technology across the board.
Integrated Intelligence in a Small Package
Drive systems offering integrated intelligence and PLC functionality are simplifying the overall design of machines that produce bottle caps for wine and liquor bottles. With a built-in drive coordinating local inputs and outputs for program selection, start and stop signals, light barrier, state and control of the scissors and error signaling, a programmable compact drive from Maxon Motor provides an integrated solution for both logic and motion control in a very small package.
Modern drives in handling systems and industry machines are designed as networks of single modules. Despite the ever-increasing complexity and trend toward miniaturization, the complete system needs to exhibit a high degree of robustness.
In wine and liquor bottling machines, a film is shrunk over the bottleneck and bottle cap. Two different modes of operation are used to cut the film to the desired length. The first method advances the reel-fed band by a fixed distance after a starting signal, then a digital signal activates a pair of scissors cutting the band. The second method uses a marking on the band which is detected by an optical reader and initiates a relative position move. Again, the scissors are activated. The selection of the mode of operation is set at the beginning by a digital signal.
Traditionally, a stepper drive controlled by the main PLC was used to cut the shrink-film. A redesign of this function uses the programmable Maxon compact drive MCD EPOS P with the goal of advancing modularization one step further by transferring intelligence to the local drive.
An important design goal is to reduce the outer dimensions of the drive and, at the same time, achieve higher forces. Use of the brushless dc motor in the MCD EPOS package combined with a ceramic gearhead (reduction ratio of 18:1) to help provide a solution is smaller than the existing controller that fits perfectly below the feeding roll with the gearhead. A toothed belt transmits the torque from the gearhead to the roll, with an additional reduction of 2:1.
Local PLC functionality built into the programmable MCD EPOS P 60W is used to control the complete cutting operation. The drive receives a digital signal from the main PLC defining the mode of operation. Upon receiving the starting signal, the complete process is controlled locally which means the signals of the optical sensor and the state of the scissors are read, the position moves with the motor executed and the scissors activated. Digital outputs provide error signals and activate the inputs.
Since the motor, encoder and motion controller are all integrated into an aluminum housing allowing up to IP-54 protection, all internal connectors are vibration-proof and suitable for harsh industrial environments. The brushless dc servomotor provides both high power density and excellent dynamic performance. A slotless winding allows smooth operation without cogging even at low speeds, which is also supported by the sinusoidal electronic commutation scheme of the controller.
The programmable version of the compact drive provides PLC functionality and capabilities as a CANopen master device. Programming of the integrated PLC complies with standard IEC 61131-3 as opposed to other small drives which may be programmed in a proprietary language.