Sensors for Automatic Passenger Counting

The Challenge

In order to highlight and target passenger safety and security on public transport, Plextek was tasked to develop non-camera, sensor-based technology, which was highly accurate, compact and unobtrusive and could be positioned in the doorway of buses, trains and trams.

The sensor needed to provide a resolution to identify multiple and simultaneous passenger movements, as well as present the client with a low material and manufacturing cost per unit.

The Approach

We first developed and optimised the necessary algorithms and produced a demonstration of how the customised technology would work. Downward-pointing rows of sensor modules above or next to the doors were installed to count the number of passengers as they entered.

A range of different ultrasonic and infrared modules were tested. The performance was then evaluated in real-world transport environments to see if there was any discrimination between the recording of people and objects.

The materials and manufacturing costs of the sensor assemblies were then value engineered and investigated to see if the project was viable.

The Outcome

Rigorous testing of the sensors proved that they had the potential to be able to overcome camera-based limitations and were able to distinguish individuals entering or leaving to very high accuracy. It was also found to be a feasible and effective solution on a variety of forms of transport, including trains, the tube, buses and also at airports.

We delivered two evaluation options; a single sensor and a dual-sensor system, for additional accuracy and resilience. Finally, we established mechanisms to reduce manufacturing costs and recommended the next pre-production steps.

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Personal Location Beacon

The Challenge

Personal Locator Beacons (PLBs) are personal safety devices for land or sea, best attached to your lifejacket or rucksack for alerting emergency services. PLBs transmit coded data bursts conforming to C/S T.001 specification.

To maximize the chance of detection our client wanted to create a product capable of transmitting on 3 different frequencies. Plextek’s challenge was to design the RF front end to accommodate triband operation, which had never previously been developed.

The Approach

Plextek designed the electronics with a particular focus on that RF front end development. This included the design of power amplifiers, antenna and antenna matching circuits. During the development stage, particular focus was paid to the power consumption requirements.

The Outcome

First Personal Location Beacon to have achieved a tri-band capability with stringent limitations on size, weight, power and cost. Plextek played a key role in helping the client to manage the electronics development whilst keeping to constraints such as battery life, cost and physical dimensions.

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Microwave Camera for Detecting Hidden Objects

Home » Case Study » Security

The Challenge

Our client, the Department for Transport (DfT), awarded Plextek with the Transport Technology Research and Innovation Grant (T-TRIG) to conduct a research study into the improvement of aviation security and screening procedures at airport checkpoints.

Objects concealed on a person or in luggage remain a threat in all public places but especially in airports. Methods currently used to image people and hand luggage, such as x-ray and terahertz systems, typically require subjects to be stationary and cooperative.

This leaves a wide range of trade-offs including equipment cost, measurement speed, screening safety and passenger congestion and discrimination.

The Approach

Plextek proposed a Microwave Camera, capable of real-time detection imaging of hidden objects, with a non-intrusive implementation approach.

Microwaves, due to the low frequency, are intrinsically safe to pass through the body and can characterise and discriminate a range of materials, including explosive devices and weapons.

A parabolic reflector enables a system of significantly lower cost compared to existing large-area sensing arrays. Technical modelling and analysis were then implemented to calibrate the reflector to receive real-time imaging. Capable of imaging people at 2-4 metre distances, this architecture can allow the scanning of people walking towards it in a ‘free flow’ passenger channel.

The Outcome

Our solution provides a safe, low cost, a fast alternative technology that had to be less intrusive and time-consuming than the current system.

Our solution uses lower frequencies and channels passengers through a corridor, allowing them to walk freely while being scanned by the microwave camera. We think this will reduce error ratings and ease passenger flow.

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Our client’s vision was for a low size, weight and power solution that could be easily deployed into the market without compromising high accuracy performance.
- Gareth Williams, Engineering Director, Plextek

The Challenge

Wave Tech, a Korean-based RF signal technology company, required a short-range Foreign Object Detection (FOD) system for airport runways.

FOD is an important security, safety and quality control in any aviation environment; where small debris, loose objects and wildlife has the potential to cause damage to airport equipment and delays to runway operation.

Our client’s vision was for a low size, weight and power solution that could be easily deployed into the market without compromising high accuracy performance.

The Approach

Our recent studies into millimetre-wave radar enabled us to produce a dual fixed and mobile antenna solution capable of detecting objects and movements from a fixed radar range of 400m.

Plextek designed and mounted a fixed antenna along the runway for stationary scanning and detection. A mobile system, a 300mm antenna for rapid rotation, was also delivered and was designed to be mounted onto the roof of a vehicle to scan the runway while moving.

Enhancing the situational awareness of the technology required utilising advanced signal processing algorithms to discriminate between wanted and unwanted signals and to separate detection of targets in close proximity to each other.

The Outcome

Our mm-wave radar solution was able to deliver 100% target illumination results in early-stage development tests, displaying accuracy and detection equivalent to a single fixed antenna.

The advanced design enabled our client to produce highly accurate FOD results with reduced deployment costs and time to market.

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