This post is the second in a series of seven chapters intended to help individuals and organisations on the journey to deploying a successful Internet of Things (IoT) transformation. The first chapter covered preparation and this post follows to discuss how to choose the right hardware. The introduction to this series can be found here along with a list of the other topic areas you will need to assess on your journey.
These are the objects that will be connected to capture data. They could be sensors, devices, controllers and so on. There is a wide variety of devices or sensors available, including temperature sensors, infrared sensors, ultrasonic sensors, touch sensors, proximity sensors, pressure sensors, level sensors, smoke and gas sensors, etc. Your use case will have highlighted which type of sensors will enable you to capture the right type of data for your project.
So how do you choose the best sensor among the many options you will find? Do you decide based on price alone? Functionality? Future proofing? Upfront investment cost versus the total cost of ownership (TCO)?
The initial cost is certainly an important factor but you also need to look at any indirect or hidden costs associated with each type of sensor. It is essential to understand how independent you want such a device to be. Do you want to install it and forget about it or do you need to maintain it on a regular basis? Does it work in harsh environments or does it require special care? Is it plug and play or will you need a 50-page user manual to install it? Can regular skilled staff install it or do you need a specialist engineer? Are the tools required for installation standard tools? What is the accuracy reading of the device and how mature is it? You need to test it as well as talk to other customers using your preferred choice of sensor to understand any reliability and operational issues they’ve uncovered during their journey.
An important factor to consider here is, whether you need the device to send accurate location information – in case the device or equipment is being moved regularly as part of operation, or inadvertently or maliciously? If this is important, you will need the sensor to have accurate position capabilities (i.e. GPS) which will affect cost and battery life to name just a couple of impacts.
When you identify a favourite sensor, start with a small pilot with clearly defined success criteria that is part of your overall strategy. During such a pilot, always consider, assess, and project how it would be if you are rolling out thousands of sensors. If it does not work at scale, you may need to revisit your choice.
The three major points to assess are sensor type, sensor cost and sensor performance.
Connectivity can have a significant impact on cost, roll out/scale and speed of deployment. Connectivity is a critical success factor for the device/sensor to send data from the field to the server.
For connectivity the key variables to consider are:
- Wired vs. wireless connection: If wireless, you may need to explore and assess various types of connectivity like Low Power Wide Area (LPWA) – LoRa or LTE, Personal Area Network (PAN) – Bluetooth or ZigBee, Wireless Local Area Network (WLAN) – Wi-Fi or traditional cellular – 2G/3G/4G. Each has its advantages and disadvantages, for example, the 3G/LTE offers roaming if required, does not work within some structures or underground. It also often has a high cost of connectivity.
- The lifespan of your connectivity method is another complexity. Is your sensor uses 2G or 3G for example or any other method that will become obsolete or unsupported in a year or two? Does the vendor provide a path forward for replacement of devices or will you write off all the investment?
- The interval of connectivity required. How time sensitive is your data? Do you need it always on or can you connect once every few hours for example (the duty cycle)?
- Availability and reliability of the connection: How critical is this data transmission for your business. If the connection is broken what will be the impact on your business?
- The quantity of data you are transmitting when you connect. Are you using a few KB of data, large images or real-time HD video that could take megabytes of data?
- Data costs: If you are paying per sensor per month you need to dig further to clearly understand what is included in the monthly fees. If your data transmission needs change how would the cost vary?
Connectivity requirements also have a significant impact on device energy consumption.
Connecting more regularly and sending larger data quantities means more battery usage and may mean additional costs.
In summary, the five major points you want to assess are the cost of connectivity, duty cycle, coverage area, data bandwidth requirement and availability requirement of connection.
If the device you choose is wireless, the battery becomes more important and the choice of connectivity protocol can be a major element in your decision. Wi-Fi, for example, allows high data throughput but is power hungry and will require battery recharging or replacing …3G is also power hungry vs LPWA which is less power needy but has speed/size limitations at present. As mentioned already, if a GPS is required, such technology is extremely power hungry. It is important to note here that certain devices coming to market are self-powered (kinetic capture, solar etc..) and offer a solution to the battery problem. Always remember, that in a wireless environment the choice of connectivity protocol is a critical factor impacting the battery life. And battery life could be a major challenge in realising the IoT solution value.
It is key to fully understand the duty cycle, the datatype/size you transmit, and the connectivity you have available in order to make an educated decision.
Short life battery does not necessarily mean that the solution is not suitable but rather that you will need to assess your business environment and how costly it is to change the battery. For example, if your equipment normally requires routine maintenance, then changing a battery may be a small cost to absorb. However, if you are looking to install and forget, then battery becomes a critical cost factor as you want to minimise trips to the device and avoid short device life.