The recent study Bluetooth Low Energy Indoor Localization for Large Industrial Areas and Limited Infrastructure discusses the use of Bluetooth Low Energy (BLE) in industrial applications, particularly in Smart Factory and Smart Farming settings. Bluetooth systems are beneficial for their low-power operation and are widely used for asset monitoring, management, tracking and localisation. The focus of this paper is on BLE-based localisation systems, which typically use radio propagation models and multi-lateration, or radio fingerprinting, to achieve high accuracy and precision. These methods rely on the received signal strength indicator (RSSI) measurements and its dependency on the distance between the transmitter and the receiver.
However, the paper highlights the challenges in achieving high localisation accuracy due to the inaccuracy of RSSI measurements and susceptibility to radio propagation phenomena. In industrial environments, where radio propagation is complex and the number of anchors (fixed reference points) is limited, achieving high accuracy is difficult. The paper proposes a set of localisation algorithms that require limited infrastructure, have low complexity, and can provide valuable location information at low costs. These algorithms were tested in a Smart Farming application for monitoring the well-being of farm animals, demonstrating reliable operation despite system-level constraints and varying propagation conditions.
The proposed algorithms are based on signal strength measurement. They allow for localising animals in a cowshed of 1600m² using only 10 anchors with an average positioning error below 8 meters.
The paper also discusses the applicability of RSSI-based localisation to different radio technologies and the limitations of these methods. The proposed approaches are designed to enable location-based services in existing systems at minimal additional costs, benefiting from the already available infrastructure, mechanisms and procedures.
Industry 4.0, or the Fourth Industrial Revolution, is the integration of digital technologies into the manufacturing process to create smart factories. These technologies include sensing, artificial intelligence, machine learning, the Internet of Things (IoT), big data, cloud computing to create more efficient, flexible and customisable manufacturing processes.
A new study by Institute of Technology and Business in České Budějovice, Czech Republic on Possibilities of Using Bluetooth Low Energy Beacon Technology to Locate Objects Internally: A Case Study describes and tests a system capable of locating objects inside buildings using Bluetooth Low Energy (BLE) beacons. The authors conducted a survey of available devices and proposed a low-cost combination of system elements, configured the system, programmed reading gates and web applications for data flow monitoring and finally tested the system in an industrial setting at a manufacturing company in Czechia.
The testing included scenarios with beacon-equipped metal crates being moved around in three different sections of the industrial hall. The study evaluated the system’s ability to detect the beacons and determine their location.
The results showed that in the case of direct visibility, the system was able to determine the distance with an accuracy of 94%. However, the measurements also showed that the signal strength was affected by shielding, resulting in worse measurement results in this case and only able to determine the exact distance only 22% of the time.
Crate with a beacon
During a load test, the system and all its sub-components were subjected to several hours of operation, during which the gateways sent requests and collected data about available beacons, processed the requests and stored them in the database. The web application allowed for real-time monitoring of data flow from the individual gateways and the number of beacons in the individual sections. No problems occurred during testing that would cause the measurements to be interrupted, demonstrating the functionality of all system components. The system was considered adequate for most use cases.
Work-in-progress (WIP) monitoring is tracking the progress of production. It allows managers to make informed decisions about resource allocation and scheduling as well as determine the current status of a job or subassembly. Work-in-progress (WIP) monitoring is part of Industry 4.0, the term used to describe the fourth industrial revolution, which use digital technologies to create more efficient and automated production processes.
WIP monitoring saves costs by identifying bottlenecks in the production process, reduces the amount manual tracking and enables proactive decisions. Also, real-time data can be used to optimise production schedules and minimise downtime, reducing the overall cost of production.
Tracking work in progress (WIP) has several advantages for manufacturing and production operations:
Improved Production Planning: By tracking WIP, manufacturers can better understand how much inventory they have at each stage of production, which can help them plan for future production runs, adjust staffing levels, and optimise production schedules.
Better Resource Allocation: WIP tracking can help identify areas of the production process where resources are being over-utilised or under-utilised. This information can be used to allocate resources more efficiently, reducing waste and increasing productivity.
Quality Control: WIP tracking can help identify quality issues earlier in the production process, allowing manufacturers to take corrective action before the product reaches the final assembly stage. This can reduce the amount of rework required and improve overall product quality.
Reduced Lead Times: By tracking WIP, manufacturers can identify bottlenecks in the production process and take action to resolve them more quickly. This can help reduce lead times and improve on-time delivery to customers.
Cost Savings: By optimising production schedules and resource allocation, WIP tracking can help manufacturers reduce costs associated with over-production, inventory storage, and waste.
Bluetooth beacons can be used to track WIP by attaching a small, low-power Bluetooth device to each job or unit of production. These beacons transmit a unique signal that can be detected by Bluetooth-enabled gateways located throughout the production line. This allows for real-time tracking of the location and status of each job or unit of production.
Some legacy system use barcodes or RFID for WIP tracking. The problem with these is the information is only as up-to-date as the last scan. Bluetooth beacons transmit all the time allowing for real-time tracking of WIP with no manual scanning. Additionally, Bluetooth beacons can be easily integrated with existing IoT infrastructure, making them a cost-effective solution for WIP monitoring. RFID and barcodes, on the other hand, require specialised equipment to read the tags. Bluetooth beacons can transmit data up to 100 meters or more, also making them more suitable for large spaces such as warehouses and factories.
Real Time Locating Systems (RTLS) can be used for both inventory management and asset tracking. Here, we explore the differences between inventory and assets and the respective benefits of using a RTLS.
Inventory is stock, parts, materials and products that move through the company while assets are equipment, fixtures and furniture the company needs to do work. Inventory tends to be sold quickly to customers and leave the company while assets tend to be be kept longer term. It’s not just companies that have inventory and stock. Organisations such as government and health agencies consume rather than sell inventory and use assets to provide services.
While there are many systems that can be used to track the quantities of inventory and assets, very few track location. Knowing you have something but not knowing where it is leads to significant inefficiencies, especially in large organisations.
Managing both inventory, assets levels and location is important to avoid shortages and the need to over-stock so as to mitigate not being able to find items. In some cases items can spoil, due to expiry dates, which makes locating them more time sensitive. RTLS provides an automatic real-time view of inventory and assets so that quantities are known when items get stolen, thrown away or otherwise leave the site.
Inventory management provides better accuracy as it’s known what is in stock so the correct quantity can be ordered to meet anticipated demand. It makes it less likely products will be oversold, when not in stock, preventing end-customer disappointment. Having optimal stock saves money. Excess stock costs money until sold that can include overheads such as storage, handling fees and insurance. Excess standing stock is also is also presents the risk of loss by theft, obsolescence and unexpected damage. A better, real-time view of stock allows demand to be analysed and optimised. Having the correct stock ultimately keeps end-customers loyal due to a better customer experience.
Asset management ensures that assets don’t have to be over-purchased to compensate for inefficiencies in finding items. Knowing you have item(s) prevents unnecessary duplicate purchases. As the RTLS is real-time there’s no need for manual audits. The automatic auditing of assets also highlights items that have become lost or stolen. Knowing where assets are ultimately reduces labour costs because employees spend less time searching.
Today’s just-in-time and busy manufacturing processes means that manual tracking of pallets for inbound and outbound shipments often can’t keep pace with the speed of production. Production and assembly requires the quick locating of components. Delays and inaccuracies due to lost components lead to increased costs, employee frustration and ultimately customer disappointment.
Competitive pressures are also driving the need to reduce labour thus reducing the capacity to manually search for items. Customisation using configured options and demand-driven production is also increasing the degree of inbound component searching that exacerbates the problems.
Even those companies using legacy tracking solutions find that location is only as good as the last barcode or RFID scan. Humans get lazy, make mistakes and don’t scan, causing pallets, crates and boxes to get lost. Many RFID readers don’t work reliably near metal components. Relying on a system that can’t find just a few items can be worse that a manual system that works but is slower. Bluetooth asset tracking solves these problems because the location is automatically collected in real-time and is continually updated.
Asset tracking can be applied to items such as components, pallets, cases, tools, returnable assets such as racks and cages as well as items on loan to ensure they are returned on time. It can improve worker safety and provide alerts in cases of congestion, perimeter deviation and lone worker distress. It can ensure forklifts are being fully utilised, are taking an optimum route, haven’t crashed into racking and haven’t gone out of an area.
The real-time visibility allows connected systems to generate confirmation and exception alerts and automatically trigger shipping processes, replacing costly manual workflows. Tracking outputs also allows confirmation that the correct things are loaded on the correct transport.
A Bluetooth-based real time location system (RTLS) increases visibility and allows the manufacturing process to adapt in real-time to short term business needs. It provides cost savings, greater efficiency and business intelligence that can be used to derive larger scale changes based on data rather than gut instinct. Overall reporting of input and outputs provides input to management reporting to monitor the business.
It’s interesting how many of our clients come to us with a problem to solve and in talking through possible solutions they often suddenly have the thought, ‘That’s IoT isn’t it?’. They weren’t looking for an IoT or Industry 4.0 solution but they got there by a different route. Indeed, it’s always best to start by solving problems rather than trying to fit technology into existing processes.
So what are the typical problems in factories? While companies usually have systems to take orders and invoice for them, what goes on in between is often a manual paper process. Knowing where an order is physically and hence how far it has been completed often requires lots of ringing round. Similarly, there are usually problems finding parts for jobs. Parts arrive in boxes or in pallets and are stored somewhere pending jobs. Finding the right pallet or box on a large site can be a challenge. It might be in storage, already on the factory floor somewhere or in transit between areas. Sometimes, delicate parts might be left in the wrong places and spoil due to excess humidity or in some cases incorrect temperature. Expensive tools and equipment tends to be shared between work areas and this can also get mislaid, lost or stolen.
All these problems cause delays in production, reduced productivity, incur penalties or future lost orders due to delayed work and cause employee frustration.
The solution is to better track jobs, parts, sub-assemblies and shared valuable tools so that they can be located on factory plans. This tracking needs to be continuous and real-time because merely scanning things in/out using barcodes is open to human error and location is otherwise only as good as the last scan. Historical data shows where things have been in the past. Analysis of this data allows blockages to be identified so that the process as a whole can be refined to improve efficiency and production.
The result is reduced downtime, less time re-ordering or re-making things that have been lost, optimum productivity and better use of skilled staff doing their job rather than searching for things.
A common problem in factories is manual searching for stock for input to manufacturing. Stock is usually stored in boxes or pallets and can be in one of many rooms, warehouses or might already be somewhere on the factory floor. A large amount of stock arrives and leaves every day leading to logistical challenges keeping up with the whereabouts of goods. Timely delivery of components or sub-assemblies is critical to ensure smooth flowing of production and making best use of factory resources.
Manual paper-based processes are extremely inefficient and prone to human error. Old fashioned RFID or barcodes are also susceptible to error because data is only as up to date as the last scan and a recent scan might not have occurred.
We offer multiple solutions for tracking stock and can adapt them to your exact needs, for example integrating with your existing systems. Once you have a tracking system in place you can use it for extra purposes such as locating jobs/work orders, monitoring machine/people capacity and providing for location based instruction/tasks. Sensing open/closed, on/off and quantities such as temperature and vibration enables diagnostics, monitoring and prognostics.
Ignition is a HMI/SCADA system used for factory machine control and monitoring. It uses web-based technology running on an on-site server. It’s configured using a drag and drop user interface to provide HMI/SCADA controls, dashboards, historical trending, database access, reporting, alarming, security, sequential function charts, redundancy and failover control.
Ignition 8.0 has support for Bluetooth in the Perspective App running on mobile devices. It reads iBeacon and Eddystone formats. This allows for functionality based on location.
Connected factory implementations require a large number of connected assets for condition-based monitoring, asset tracking, inventory (stock) management or for building automation. Bluetooth is a secure, low cost, low power and reliable solution suitable for use in connected factories. In this post, we examine the reasoning behind some out-of-date thinking on industrial wireless, uncover the real problems in factories and provide some explanations how Bluetooth overcomes these challenges.
Operations teams are usually very sceptical about industrial wireless. They have usually tried proprietary industry solutions using wireless with mixed results. They might have experienced how connections, such as WiFi, can become unreliable in the more electrically noisy areas of factories. The usual approach is to use cable. However, this can become expensive and time consuming. Using cable isn’t possible when assets are moving and becomes impractical when the number of connected items becomes large as in the case of connected factories. As we shall explain, Bluetooth is intrinsically more reliable than WiFi even through they share the same 2.4GHz frequency band.
There’s usually lots of electrical noise in an industrial environment that tends to be one of two types:
Electromagnetic radiation emitted by equipment. This typically includes engines, charging devices, frequency converters, power converters and welding. It also includes transmissions from other radio equipment such as DECT phones and mobile telephones.
Multipath propagation which is reflection of radio signals off, usually metallic, surfaces and received again slightly later.
It’s important to understand how Bluetooth and other competing technologies react to these types of interference. There’s a useful study (pdf) by Linköping University, Swedish Defence Research Agency (FOI) and the University of Gävle on noise industrial environments.
Noise in industrial environments tends to follow the following spectral pattern:
There’s usually lots of electrical noise up to about 500MHz. This means wireless communication using lower frequencies, such as two way radio, exhibits a lot of noise. Pertinently, several wireless solutions for industrial applications use frequencies in the 30–80 MHz and 400–450 MHz bands. Bluetooth’s and WiFi’s 2.4GHz frequency is well above 500MHz so exhibits better reliability than some industrial wireless solutions. Incidentally, in the above charts, the peaks around 900 MHz and 1800 MHz mobile phone signals and 1880–1890 MHz come from DECT phones.
The magnitude of multipath propoagation depends on the environment. It’s greatest in buildings having highly reflective, usually metallic, floors, walls and roofs. If you imagine a radio signal wave being received and then received again nanoseconds later, you can imagine how both the amplitude (peaks) and the phase of the received signal becomes distorted over time. Bluetooth uses Adaptive Frequency Hopping (AFH) which means that packets transferred consecutively in time do not use the same frequency. Thus each packet acts like a single narrowband transmission and there’s less affect of one packet on the next one. However, what is more affected is amplitude which manifests itself as the received overall signal strength (RSSI). RSSI is often used by Bluetooth applications to infer distance from sender to receiver. We will mention mitigations for varying RSSI later.
It’s important to consider what happens when there is electrical noise. It turns out that technologies invented to ensure reliable transmission behave much less well in noisy situations. One such technique is carrier sense multiple access (CSMA), used by WLAN (WiFi), that listens to the channel before transmitting and waits until a free channel is observed. CSMA and automatic auto repeat (ARQ) also have re-transmission mechanisms. The retrying can also incur significant extra traffic that can overwhelm the communication in noisy environment. Bluetooth doesn’t use such schemes.
The previously mentioned research classifies different wireless technologies according to the delay when used in noisy environments:
Bluetooth (and WISA) is a good choice for noisier environments. It’s particularly suited for applications with lower data rates and sending at periodic intervals.
A final consideration is interference between Bluetooth and other technologies, such as WiFi, that use similar 2.4GHz frequencies. As mentioned in a previous post, there’s negligible overlap between Bluetooth and WiFi channel frequencies.
In summary, Bluetooth is more suited to electrically noisy environments and also offers low cost, low power and secure wireless communication.
These conclusions correlate well with our own empirical observations. We have found that Bluetooth advertising is still received in environments we have measured, using a RF spectrum analyser, to be electrically noisy around 2.4GHz . We believe this is because Bluetooth advertising hops across three frequencies such that there’s less likelihood of noise on all three. Advertising is also very short, typically taking 1 or 2 ms, making the coincidence of the noise and the advertising less likely than would be the case of a longer transmission.
It has been our experience that solutions using Bluetooth advertising are more reliable than those using Bluetooth (GATT) connections, especially in noisy environments when it’s difficult to maintain the chatty protocol of a connection over a long time period. In noisy situations, advertising is usually seen on a future transmit/scan if the first advertising is lost. By coincidence or design, Bluetooth Mesh is built on communication via advertising rather than connection and for this reason is also reliable on the factory floor.
However, using Bluetooth isn’t a silver bullet. There are situations where factories, or more usually parts of factories, have reflective surfaces or unusual radio frequency (RF) characteristics stretching into unforeseen frequencies. Poorer performing WiFi also needs to be considered in context of choosing between Ethernet and WiFi gateways and Bluetooth mesh.
It’s important to do a site survey including RF spectral analysis. This will uncover nuances of particular critical locations or coverage that can drive subsequent hardware planning. It can also feed into requirements for software processing, for example particular settings for processing within a real time locating system (RTLS) to cater for more varying RSSI.