Feature Sensors & sensing systems
The USB sensor solution
The sensors industry has responded to changing demands by creating a USB technology for the load cell and sensors market. Navid Mokhberi, of FUTEK Advanced Sensor Technology, takes a look at the technology and its benefits, and explains what applications it could be used in
it now offers USB output on its line of load cells, torque sensors and pres- sure sensors, as well as any strain gauge type transducers.
Developments
In January 2008, engineers at the company began their research and development into the new USB sensor solution, having originally worked on USB technology for sensors back in 2004 with FUTEK VCAL – a portable calibration verification platform. The advantage of offering a USB
solution was clear. Sensors with analogue output could seamlessly interface with digital devices. As the Traditional Sensor System
W
ith the engineering field being challenged by innova- tive and complex sensor applications, the need for
a low cost way of capturing data more effectively has grown in impor- tance. Today, applications across the board are becoming more and more involved, so it was only a matter of time before a quick and more efficient solution was needed to obtain output data. USB drives have been popular for
a long time in consumer markets. As this trend moved into the industrial electronic arena, however, the sensor industry responded by creating a USB sensor technology for the load cell and sensors market. The USB solution offers portability as well as universal capabilities with computers, handheld displays and PDA devices. One of the main reasons why
mechanical engineers decided to go digital was due to the speed in which a USB output could obtain data compared to the traditional ana- logue output. Basically, the USB technology is capable of transferring larger amounts of data in a much shorter amount of time. FUTEK Advanced Sensor
Technology is one manufacturer that has integrated the USB solution, and
Design Solutions MARCH 2010
Compared to a traditional sensor system, the USB solution removes the need for an amplifier, analogue filter, power supply and multimeter
diagram (left) indicates, in order to build a traditional sensor system platform there are a number of instru- ments to consider. An ideal platform would include an amplifier/signal conditioner with an active analog filter, which will require an external power supply. In addition, a multimeter (display) and data storage is necessary. The traditional
sensor systems also had some shortcomings, including the power consumption, unwanted noise and voltage drop out, that would occur if the cable range between the amplifier and display instrument was too long. Even if one disregards the economic factor behind such a platform, the task of integrating these instruments all together is no simple feat. The USB sensor solution, however,
removes the need for an amplifier (signal conditioner), analogue filter, power supply and multimeter. As well as lower costs, this offers the benefits of high resolution digital output and an integrated digital filter to reduce 50HZ/60HZ, plus high frequency noises and the ability to increase the sample rate for high speed applications. This also has the capability to store calibration values inside the on-board non- volatile memory (to apply the real time calculation to account for non-linearity) and other configurations which are usually stored in a TEDs chip which is no
longer needed. The presence of a powerful
micro-controller beside a high accuracy delta-sigma Analog to Digital Converter (ADC) not only eliminates analog circuitry (reducing the sensitiv- ity to environment conditions such as temperature, humidity and noise), but also introduces an intelligent digital system which can activate internal
Monitoring race cars with pressure transducers
G
inetta Cars, a designer and builder of cars for both the race track and road, has chosen Variohm’s lightweight EPT3100 pressure transducers to monitor oil, fuel and water pressure across its G50 series race cars.
The 300 bhp G50 ‘Cup’ race car is used for the single-make Michelin G50 Championship which starts again in April. With
an upgrade this car is eligible for British, European and World GT4 racing and took the British GT4 title in 2008. A newly intro- duced G50Z version has a 400 bhp Ford Zytek engine and is aimed at top level GT sprint and 24 hour racing. The latest deriva- tive, the G50HC (Hot Climate), is built for the Middle East race car market and is designed for track temperatures up to +60ºC. Throughout the G50 series, engine control unit and data logging systems are used to ensure optimum performance, and
Variohm’s EPT3100 series pressure transducers are built for such challenging applications. These have a thin film measuring cell and high level output circuit technology that provides pressure out- put from 0.25 to 4000 bar in several range options with accuracy better than ±0.8% and stability more than ±0.1%. Output options include 0 – 5 V, ratiometric and 4-20 mA with up to 32 V input. Additional features of the IP66 rated sensors include a 1000g shock rating and 25g peak
vibration rating at 20 to 2000Hz. There is also a choice of miniature or standard DIN43650 connectors, or flying leads, and, for tough applications, these have an over-range pressure rating of 2x and burst pressure capability to 5x, with a rated life of more than ten million pressure cycles.
Variohm Eurosensor T: 01327 351004 www.variohm.com Enter 252
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