Automated parking structures are popping up all over. Three are currently operating in the U.S.—in Washington, DC, New York City, and Hoboken, NJ—but there are many more in Europe and Asia. The user experience is cool, the concept is environmentally friendly, and the technology is state-of-the-art.

Automated parking systems enable high density storage by eliminating the need for ramps and stacking cars literally bumper to bumper and door to door. Customers drive into the entry bay, exit their cars and activate the system by pushing a button. Advanced algorithms determine where the car will be stored and moves it to the storage location. When the customer returns, the system retrieves the car and quickly delivers it to the driver in an exit-facing position. Cars are parked with their engines off, significantly reducing exhaust emissions, and drivers enjoy a fast, safe valet-parking experience—without the valet.

Automated parking systems include mechanical elements such as shelves (racking system), elevators and shuttle cars, which are guided by programmable logic controllers (PLCs) and orchestrated by an automated parking management system. In December 2006, the City of Hoboken chose to upgrade its automated parking facility, one of the first in the U.S., with a capacity of more than 300 cars. The project included repair of mechanical and electrical systems and replacement of the control systems and the management software.

Unitronics, a maker of industrial controllers, got the job, and the company’s Vision280 PLC was chosen for the heart of the system because of its integrated touch-panel interface and rich feature set. Key features include remote access and a local database, both of which promote high system availability and reliability.

Unitronics chose a distributed control topology to provide enhanced efficiency, manageability and reliability. A Vision280 PLC is installed in each conveying element, and all controllers are connected to one main TCP/IP network.

Elements with static control cabinets (e.g. elevators) are connected by wires. Components with moving control cabinets (e.g. shuttle cars) are connected via Wi-Fi, a wireless Ethernet. The wireless connection eliminates the need to lay cables throughout the site, enables moving parts to be easily networked and allows technicians to access any PLC from anywhere in the building using a Wi-Fi-enabled PC. The Vision280’s graphical HMI (human machine interface) enables local handling of single components, problem isolation and manual operation of specific parts.

Information regarding the location of each car (identified by a specific ID) is saved in the PLC’s internal database. This means that should a failure of the central computer occur, the garage can continue to locate cars in a semi-automatic or manual mode, using the information in data tables. Unitronics uses data tables for similar purposes in the logistics systems and automated warehouses that it designs and builds. In such systems, Vision PLCs keep records of the location and loads they handle (pallets, crates, containers, etc.), enabling semi-automatic operation of the warehouse in case of malfunction.

The automated parking system includes support for advanced communication features available in the Vision PLCs. One such option lets the controllers be connected to a GSM cellular modem, so the controller can send short message service (SMS) messages to technicians in case of system faults. Technicians then can request and receive data from the PLC via their mobile phone, and send commands to the PLC via SMS to quickly modify parameters such as speed and acceleration.

Another available option is integration with a license plate recognition (LPR) system to enable automatic recognition of cars entering the bay. This system can be connected to the Vision PLCs without requiring a unique protocol, thanks to the system’s protocol function block. In industrial applications, this software feature is used to connect PLCs to a variety of external devices, such as bar-code readers, without the need for extra development.

A Vision280 in the reception area is responsible for moving a car to and from an optimized spot within the garage. Customers set the parking process in motion by entering a username and password on the Vision280’s HMI touch screen, similar to using an ATM. The HMI also makes it easy for garage technicians to conduct immediate diagnostics and to troubleshoot the system.

Using Unitronics’ unique Info Mode, technicians and operators can check the real-time status of sensors, distance-measurement lasers and other parameters. If there is a problem with a moving part, the operator can check the PLC located on the part in question and immediately determine whether there is a control problem or a fault with a sensor or motor drive.

Because the automated garage is a multi-level building, sometimes as high as 60 feet, it is not always feasible or handy to have a technician go to the physical location of the PLC to diagnose a problem. In that case, technicians use the PLC’s Remote Access utility. This lets approved personnel remotely monitor and access all PLCs via a PC located in the control room on the ground floor, or from anywhere worldwide via the Internet.

Technicians access the desired PLC from the computer and the view they see on their screen is identical to the user interface display of the PLC itself, except they operate it using a keyboard and mouse. The remote access feature is useful in standard industrial applications as well. Connected by Ethernet local area networks, GSM/GPRS modems or Internet-enabled networks, the PLCs can be operated from as close as a floor manager’s office or from as far away as a system integrator’s PC in another country.