Figure 1. The Sandbags Super 50 can produce up to 2,000 sandbags/hr, giving local agencies the ability to respond quickly in emergency situations in order to protect property and save lives.
During natural disasters, sandbags are used to protect people and property. In addition to becoming lifesaving tools during floods and storms, sandbags are also used to provide a steady base for oil, gas, and water pipelines. Sandbags are used in these situations because they provide consistent, flexible weight that enables them to become effective barriers and ballast in a variety of applications.
Sandbags and Dynapac Design Group, a machine builder OEM headquartered in Carlsbad, California, enlisted the aid of InduSoft and its value-added reseller Quantum Automation to improve the monitoring capabilities and control of their sandbagging machines (Figure 1).
For this process, operators load sand into a hopper on the Sandbags Super 50 trailer (Figure 2). A sand delivery conveyor belt feeds equal amounts of sand into a loading spout on which an empty sandbag is attached. Using a proprietary measuring system, an accurate volume of sand is delivered and is then discharged into the sandbag.
Figure 2. The Sandbags Super 50 Machine is a mobile operation made more efficient by connectivity to the central operations center.
Each sandbag is dropped onto a conveyor, sewn closed as it moves along the belt and raised to a greater height. A third conveyor then loads the sandbags into a large supersack with the guidance of an operator. One or more supersacks are then loaded onto a flatbed truck to be delivered to the sites that need the sandbags.
A complete factory on wheels
Investigating the Sandbags Super 50 at a more granular level reveals the many pieces that make the system a complete factory on wheels. All components have been chosen not only for functionality, but for their ability to reliably perform over the long haul in highly abrasive conditions in outdoor environments. The entire assembly rides on a heavy-duty trailer so it can be transported as needed.
Operating personnel perform some manual actions, but the process is mostly automated, boosting overall productivity to more than 2,000 bags/hr. An infeed hopper must be replenished by operators using a skip loader or other similar equipment, with the hopper’s 4.5 cubic yard capacity minimizing the number of required refills.
There are two identical and parallel filling systems served by the in-feed hopper. On each line, a constant-speed sand conveyor belt is operated by a 7.5 hp hydraulic pump to deliver sand into a bag-dispensing hopper. Hydraulics were chosen as most suitable for this service due to the heavy load and frequent start/stop duty cycle of once per second.
A volumetric measuring system is used instead of a weighing system due to its superior reliability and reduced maintenance requirements. The resulting accuracy is more than enough for the application as bags are filled at ±1 lb, or 2% of a standard 50-lb sandbag. Operators must perform a basic column calibration procedure at the beginning of each day to account for local sand density, and this brief operation fine-tunes the sand conveyor belt start/stop cycles to optimally fill the hopper spout.
A proximity sensor detects when the operator has positioned an empty bag on the hopper spout, at which time the bag is filled automatically and then dropped onto the production conveyor belt for transport to the sewing station. After the manual sewing operation is completed, an incline conveyor takes the sandbag to a reversible shuttle conveyor which is used to fill supersacks with sandbags. Supersacks vary in size and can generally accommodate anywhere from 25 to 200 bags, with operators selecting the appropriate size and corresponding number of sandbags.
All conveyors are driven by variable frequency drives (VFDs) and gear motors. This allows speed differentials to be set as needed to separate the bags for the final loading operation and also provides a ramped starting and stopping action. The two lines use a total of six conveyors.
Two PLCs provide the brains of the operation. PLC1 provides supervisory real-time control to monitor sensors and operate sandbagging conveyors. PLC2 performs data acquisition, as well as control of auxiliary systems including an air compressor. PLC2 also controls, collects data from, and monitors the system for a self-contained onboard diesel generator which powers the machine.
Most control system input/output (I/O) signals are discrete (on/off), although some analog input signals are used to monitor pressures, temperatures, voltages, and environmental conditions. In addition to equipment control signals, discrete inputs monitor buttons and switches, and discrete outputs drive signal lights. The system is designed so no analog closed-loop control is needed, simplifying operation and maintenance and reducing interference issues with static and electrical noise.
This factory on wheels was designed from the sand up to reliably fill sandbags at the greatest possible rate, overcoming design obstacles along the way.
Extensive communications pose challenges
Sandbags contracted with Quantum Automation to create a full solution for the sandbagging machine. Initially, machine monitoring was to be accomplished by a C programming language application running under Linux. But during the early alpha development phase of the machines, it quickly became apparent that this approach would be too costly in terms of engineering and development costs.
Figure 3. This screen creates a dashboard for the machine showing weather information, alarms, location, and performance.
A large number of drivers would be needed to interface communications between each machine and the Sandbags MES Network Operations Center located in Las Vegas, Nevada. In addition, custom development would cause security, updating, and ongoing maintenance of the machines to be unreasonably expensive and complex, so a completely different solution was required.
The Sandbags machines, located at various sand quarries within the United States, need to communicate via cellular modem, Wi-Fi, or local area network (LAN) back to the Sandbags operations center. Each location provides video streaming from two on-site Industrial IP cameras. The machines also send local ambient environmental information taken from an onboard Airmar WeatherStation, along with machine status and utilization metrics from the PLCs and the operator interfaces back to the Sandbags operations center (Figure 3).
All these design requirements necessitated a solution that could easily communicate with and interface to each of these disparate devices.
Off-the-shelf solution cuts costs
Once the decision was made to avoid a fully custom monitoring system, it was easy to settle on a PC-based off-the shelf software solution which would communicate with a PLC-based control system. The I/O count, programming functionality and networking needs led the design team to select an IDEC FC5A-D12S1E PLC for each of the two PLC control units.
This PLC meets the requirements in terms of performance, ability to operate in harsh environments, a compact footprint, and a reasonable price. It’s also easily expandable with additional I/O and offers integrated Ethernet communications. Expandability is modular, which allows the addition of I/O or even additional controllers if so required.
With the controllers selected, it was time to choose the associated human machine interface (HMI) system. The natural choice for local onboard operator interfaces was the IDEC HG1 and HG3. The basic HG1 units serve as operator panels, while the larger and more advanced HG3 acts as the supervisory panel. These interfaces give the operators local visibility into equipment operation along with the ability to change machine settings.
Remote access requires advanced engineering
The remote HMI solution was a bit more involved. The list of required design features was extensive: alarming, Microsoft SQL server connectivity for MES and historian, emailing, FTP file transfers, graphics and design tools, IP protection, embedded ActiveX controls, OPC connectivity, reporting and PDF exporting, a usable symbol library, thin client configuration, trending, and troubleshooting. Any of these would be extremely difficult to successfully code from the ground up using a C programming language application.
Fortunately, all of these features are included in InduSoft’s Web Studio (IWS) PC-based HMI software. In fact, as the project developed and the team found out how capable the InduSoft product was, there was an increase in the amount of information users wanted the system to provide.
IWS is a versatile development platform with a quick learning curve and acted as a bridge among the system’s many components. In particular, native IWS communications drivers are key to the project’s success as they enabled communication without the need for programming. Advanced graphical features allow for a detailed view of the machine functionality, while the native video streaming capabilities provide useful live surveillance.
For the hardware platform to run InduSoft onboard the machine, Quantum Automation specified a fast, powerful and rugged industrial PC. The Advantech UNO-2184, running Windows 7 Professional, offered the ability to use native InduSoft Web Studio drivers to integrate the machine processes together.
This PC communicates with the PLCs using the industry standard Modbus TCP/IP protocol over Ethernet. Each machine utilizes an eWon EW2620A secure cellular remote access router to provide virtual private network (VPN) remote access, alarm notification, and software updates. The eWon unit is also used for remote troubleshooting of the PLC and operator interfaces. The eWon unit was essential during startup and the alpha-development phase.
Located on the machine is a Moxa AWK-5232-US industrial IEEE 802.22a/b/g/n dual wireless AP/bridge/client. When the device is in the “Wi-Fi communications mode”, the InduSoft Web Studio application sends streaming video from both cameras plus the PLC data along with the AirMar WeatherStation data back to the Network Operations Center.
If the sand-bagging machine is parked at a site for an extended period of time, main power and Cat. 6 Ethernet cable can be run directly to the machine instead of utilizing a portable generator and the cellular or Wi-Fi modems. In this case, the LAN cable can provide real-time data and video to the Sandbags network operating center.
Monitoring machines from the operations center
Located in the Sandbags Network Operations Center is an Advantech HPC-7480 Mission Critical Server running Windows Server 2008. Also at the center is a PC with Windows 7 Professional installed and running an InduSoft Web Studio application displaying operations information. An eWon eFive VPN appliance is used for communications, and it has the capability to communicate with up to 25 individual Sandbag machines in the field. The VPN appliance can be upgraded to communicate with 100 remote machines.
On-site video is streamed from the machine and is used to provide security, operational assurance, and visual communications to assist the company operations manager. This makes the job site more efficient and records the entire sandbagging process operation, so that there is a continuous video record in the event of an injury or other incident.
Figure 4. PC-based software and specialized communications hardware allow each sandbag machine to send GPS information and local video back to the central operations center.
The AirMar WeatherStation has a global positioning system (GPS) to determine where each Sandbags machine is located to meet asset management tracking requirements (Figure 4). It also provides wind direction and speed, along with barometric pressure for forecasting precipitation and weather events, in order to determine if production should be stopped or accelerated because of extreme weather conditions.
The PLCs and local operator interfaces provide round-the-clock control and status of each machine. The PLCs provides sandbag counts from the two conveyors and computes bags-filled versus bags-delivered to calculate the process yield on a continuous basis. It also provides a total bag count for the day, week, month, or job for billing and other purposes.
The PLCs also monitor the status of the onboard equipment to optimize maintenance cycles and improve equipment efficiency, and these and other metrics are used for overall process availability calculations. Emergency button usage for each machine is also tracked throughout the system.
Smooth startup
The control system integration for the Sandbags Super 50 sandbag machine was completed by Gina Roberts from Dynapac. As an OEM machine builder, Dynapac provided the equipment fabrication and automation services. The final project startup was completed cooperatively among Roberts, Mark “Gil” Supnet, and Chris Doan of Quantum Automation. InduSoft provided engineering assistance for configuring of the Web thin client and the mobile-access applications, which is used for the iPad and Android mobile devices utilized on-site and at the Network Operations Center.
Special attention was given to electrical component grounding in order to minimize EMI and RFI. Another high priority was protecting the electronic components by placing them into steel enclosures fed with clean air as sand is very abrasive and can quickly damage electronic components. This configuration helps to control internal enclosure temperatures, a necessity as many sand quarries are located in remote or inhospitable areas where the temperature extremes can vary from -30 °F to more than 120 °F.
Four billion sandbags are made and sewn by hand each year worldwide, a slow and expensive manual process. The Sandbags Super 50 can produce 2,000 sandbags/hr, which empowers local agencies to act quickly in order to protect property and save lives.
Looking forward, Sandbags is planning to build approximately five more of the Super 50s and five of their newer Super 44s. Each machine will include an InduSoft Web Studio runtime application running on an Advantech UNO-2184s industrial PC.
The utilization of InduSoft Web Studio in the Sandbags Super 50 machines saved many months of specialized HMI and SCADA development time as compared to using a C programming language in a Linux environment. This created a final product which is much easier to maintain, resulted in greater projected operating efficiencies, lowered overall project developmental costs substantially, and provided the project managers with predictable results to ensure project success.
Automation and remote monitoring of what were once manual and local operations increases productivity, cuts costs and improves safety. This allows users to respond more quickly to flooding, and also increases the efficiency of other operations which use sandbags.