Category: Engineering

LEXUS SUSPENSION INNOVATIONS

Tom Denton1 Comment

Throughout the six generations of success, the Lexus ES has been famous for its smooth, quiet and refined ride. Now this signature quality has been taken to an even higher level in the all-new 7th generation of the luxury sedan thanks to a detailed and innovative approach to suspension design and packaging.

The attention to detail produced a new Swing Valve Shock Absorber with an ultra-low velocity valve – a world-first in the industry. In simple terms, this innovation makes sure an appropriate damping force is provided when even the slightest movement is experienced in the car’s wheels and suspension. This makes for a comfortable, unruffled ride and a stable feel, whether you’re pulling away slowly, or driving at speed on the highway.

The benefit is gained in the way the flow of oil is controlled inside a new valve arrangement. As well as a main valve, the ES’s shock absorbers have an additional ultra-low velocity valve, which allows for very low oil speed operation; at low to high oil speeds, the main valve opens to suppress the damping force, giving supple ride comfort.

Delivering superior standards of both handling stability and ride comfort is a big ask but it was a challenge Lexus was ready to meet by drawing up a new double wishbone rear suspension design. Critically, the system’s trailing arms have been located with pinpoint accuracy to give the set-up the rigidity it needs to give true, linear steering response to the driver’s use of the wheel and excellent handling stability.

Much of the testing to evaluate the new ES’s ride and handling took place in Europe where the development team could be sure of a wide range of road types and surfaces, from no-limit German highways, to winding mountain routes and urban streets with rough surfaces. Further testing was carried out on track, including at the famous Nürburgring, and in California.

At the same time as Lexus’ engineers determined the optimum suspension performance, they also took care to produce a design that doesn’t compromise the size or convenient shape of the boot. To meet this requirement, they placed the shock absorbers closer to the back of the rear seats and mounted them separately from the coil springs.

  • Lexus applies new technologies and designs to further enhance ride comfort and handling stability in the all-new ES luxury sedan
  • World-first Swing Valve Shock Absorber has ultra-low velocity valves for precision damping performance at very low speeds
  • New-design double wishbone rear suspension
  • Systems optimised for rigidity, light weight and compact design

(Source: Lexus Europe Newsroom, https://newsroom.lexus.eu/lexus-pushes-the-boundaries-of-ride-comfort-with-world-first-suspension-innovations-in-the-all-new-es/)

 

Cycle recognition and emergency braking

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Introduction

 

Another narrow escape: a cyclist appears as if out of nowhere and suddenly crosses the road. Distracted by the search for somewhere to park, the driver is powerless to avert what appears to be an inevitable disaster. Yet Bosch’s new emergency braking system with cyclist detection prevents any serious consequences, automatically bringing the car to a full stop from 40 kph. Everyone makes it through the incident, shaken but unharmed. As soon as the emergency braking system’s radar or video sensor detects an imminent collision, the Bosch iBooster initiates full braking in just 190 milliseconds – less time than it takes to blink twice. “Driver assistance systems are the next step along the path toward accident-free driving,” says Bosch board of management member Dr. Dirk Hoheisel. “These electronic assistants are always vigilant and, in emergencies, they respond more quickly than people can. They provide support just where drivers need it – in busy city traffic.” Emergency braking systems are one of the most useful assistance systems, particularly when it comes to responding to cyclists and pedestrians, the most vulnerable of road users.

 

More protection where most needed

In Germany, bicycles are involved in one-fourth of all accidents resulting in personal injury. According to the German Federal Statistics Office, 393 people were killed in such accidents in 2016 alone – roughly 12 percent of the country’s total road fatalities. Some two-thirds of these accidents involve a car. Equipping every car in Germany with an emergency braking system that can detect cyclists would prevent almost half (43 percent) the bicycle/motor vehicle accidents that result in personal injury, or at least mitigate their severity. “An emergency braking assistant may reduce braking distance by the few crucial centimeters that can mean the difference between life and death,” says Gerhard Steiger, president of Bosch’s Chassis Systems Control division. The European New Car Assessment Program, or Euro NCAP, has also recognized the importance of emergency braking systems for road safety. Starting in 2018, the consumer protection association’s star rating system will include emergency braking with cyclist detection. Emergency braking systems with pedestrian detection have been part of the rating system since 2016.

Electronic assistants growing in popularity

In light of rising volumes of road traffic, driver assistance systems offer the full package – and hold the key to increased road safety. They keep cars in their lanes, warn of obstacles in the blind spot when changing lanes, provide support for pulling into and out of parking spots, and help maintain following distance, to name just a few examples. Bosch is constantly honing the technology behind these driver assistance systems: sensors supply increasingly precise images of the car’s surroundings, and their interaction with actuators, such as braking and steering, is steadily becoming faster and more efficient. In this way, driver assistance systems are not only preparing the path toward automated driving, but are already delivering stress-free and relaxed driving. No wonder, then, that the spread of electronic assistants is picking up. A Bosch survey found that half of all new cars (52 percent) in Germany have at least one driver assistance system on board. The trend is toward consolidating multiple assistance functions on one sensor, as demonstrated by car exit warning, a new function developed by Bosch.

Radar offers a constant over-the-shoulder view

Bosch’s rear mid-range radar sensors, which monitor lane changes on the freeway, can also keep city drivers from making a dangerous mistake: after parallel parking at the curb, drivers often get out of their cars right away – without looking over their shoulder. This has led to countless cyclists getting painfully up close and personal with car doors as they are knocked unceremoniously to the pavement. But Bosch’s car exit warning can help. It is active for all car doors and warns the occupants – even several minutes after the ignition has been turned off – before they carelessly get out of the vehicle. Mounted to the left and right of the rear of the car, the Bosch sensors monitor traffic. Within a 20-meter radius, the sensors can detect other road users who are approaching from the rear, or who are already to the side or rear of the car, and promptly warn the driver before they open their door.

 

(Source: Bosch Media)

What is WLTP and how will it work?

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The current lab test – called the New European Driving Cycle (NEDC) – was designed in the 1980s. Due to evolutions in technology and driving conditions, it has become outdated today. The European Union has therefore developed a new test, called the Worldwide Harmonised Light Vehicle Test Procedure (WLTP). The EU automobile industry welcomes the shift to WLTP and has been contributing actively to the development of this new test cycle.

 

Good update here: http://wltpfacts.eu/what-is-wltp-how-will-it-work/

Electrification and internet in the car

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Bosch is linking new technologies to gasoline and diesel

  •     Gasoline engines: 350 bar for direct injection
  •     Diesel engines: 48-volt hybrid to reduce nitrogen oxide emissions
  •     Dr. Rolf Bulander: “Bits and bytes are making cars more efficient”

Paper for download: Dr. Rolf Bulander – Powertrain optimization using a comprehensive systems approach

Lawmakers have mandated economical, low-emission vehicles. Car buyers want vehicles that are safe and that offer more convenience and engine performance. At the International Vienna Motor Symposium 2015, Bosch presented numerous innovations that meet all of these requirements. “Bosch technology is making cars more efficient, more convenient, and more fun to drive,” said Dr. Rolf Bulander, member of the board of management of Robert Bosch GmbH and chairman of the Mobility Solutions business sector. All three aspects come together in the Bosch boost recuperation system. In the New European Driving Cycle, the 48-volt hybrid can cut CO2 emissions by 7 percent (based on compact class). Thanks to its electric-supported coasting, the car offers a smoother ride and can deliver up to 150 Nm more torque on demand.

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Connected electronic horizon: efficiency thanks to real-time data
Innovative advances will transform automotive powertrains over the next few years. “Electrification and connectivity will give a further boost to gasoline and diesel engines,” predicted Bulander. “Bits and bytes are making cars more efficient.” Electrified vehicles stand to gain tremendous benefits from connectivity. They are safer, more efficient, and more fun to drive. One example of how this works is the connected electronic horizon. In the future, this Bosch technology will supply essential traffic information about construction sites, traffic jams, and accidents in real time. From this basis, it will be possible to further improve existing functions such as start-stop coasting. At the same time, plug-in hybrids can use the system to implement a predictive operating strategy. Such technologies can cut CO2 emissions by a double-digit percentage.

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Even after 2020, the vast majority of new cars will be powered by fossil fuels
In his presentation, Bulander reaffirmed that internal-combustion engines will remain the basis of efficient mobility. Even ten years from now, the vast majority of new vehicles worldwide will be powered by fossil fuels. Europe, the U.S., and China will raise the legal requirements for engine efficiency still further over that same period. Starting in 2021, the average new car in the EU will have an emissions cap of 95 g of CO2 per kilometre. Based on the current situation, advances in engine design should make it possible to achieve these values. The CO2 emissions for a gasoline engine in the subcompact class can be reduced to 85 g per kilometre, and for a diesel engine, that figure can be even lower than 70 g per kilometre. Enhanced aerodynamics and reduced rolling friction could once again lead to further improvements. Vehicles in the premium class and SUVs will need additional electrification.

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Engineering turns its attention to real driving emissions
In addition to current emission regulations, engineers are increasingly focusing on real driving emissions. The European Union is discussing whether to introduce real driving emission tests starting in 2017. This measuring method for diesel cars concentrates primarily on the emissions of nitrogen oxides and carbon monoxide in real-life driving situations. For cars with gasoline direct injection, the focus is on the level of particulates emitted. A number of vehicles currently in production already expel an extremely low amount of emissions – for example, during rapid acceleration or at high speeds. Now it’s time to drive the spread of this capability and develop cost-effective technologies that will ensure compliance, whatever the driving conditions. Bosch presented several approaches at the International Vienna Motor Symposium that support this endeavor. Bulander put special emphasis on interlinking the domains of electrification, automation, and connectivity: “Bosch pools these aspects in the vehicle and creates ideal systems,” he said.

One example of this approach is the innovative direct injection system with laser-drilled spray holes in gasoline engines. The holes’ precise edges swirl the fuel in the combustion chamber in such a way that it burns extremely efficiently. Increasing the injection pressure from 200 to 350 bar cuts particulate emissions to an even greater extent – especially under high load points and dynamic engine operation. Bosch debuted this refined version of its gasoline direct injection system at the Vienna Motor Symposium.

In diesel engines, electrification reduces nitrogen oxide emissions right in the engine, making exhaust gas treatment still more efficient. Bulander demonstrated this by presenting Bosch’s new 48-volt boost recuperation system. Through the judicious application of boosts, the system can markedly reduce untreated nitrogen oxide emissions, especially at high loads or when the car is accelerating. The crucial factor here is that this effect cuts emissions directly at the point of combustion by up to 20 percent. This has the effect of significantly lowering exhaust pipe emissions: Bosch believes the system could allow the storage catalytic converter to reduce nitrogen oxide emissions by up to 80 percent. Electrification will also increase the level of efficiency for urea-based systems as well (SCR catalytic converters). These exhaust gas treatment applications consume much less AdBlue, which means the fluid doesn’t need to be refilled as often.

(Source: Bosch Media)

Automated driving

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Bosch makes Hollywood fiction a reality

K.I.T.T. replica co-stars at the CES in Las Vegas

  • Test cars fitted with Bosch technology can already drive themselves
  • Bosch is developing automated driving in California and Germany
  • Bosch sensors are the eyes and ears of modern vehicles
  • Bosch iBooster paves the way for automated driving
  • Bosch to present its technology portfolio at the Vehicle Intelligence Marketplace

Figure 1 At the CES in Las Vegas, Bosch will not only be presenting its extensive product portfolio for driver assistance functions and braking systems at the Vehicle Intelligence Marketplace. The company will also be exhibiting a true Hollywood legend: K.I.T.T. from the action series “Knight Rider”.

Hollywood did it first: in the 1980s, the dream factory created the action series “Knight Rider”, featuring a speaking and – more importantly – self-driving Pontiac Firebird Trans Am named K.I.T.T. Nearly 30 years later, automated driving is no longer just another TV fantasy. “Bosch is making science fiction reality, one step at a time,” says Dr. Dirk Hoheisel, who sits on the Bosch board of management. Cars equipped with Bosch technology can already drive themselves in certain situations, such as in traffic jams or when parking. Bosch will be presenting its solutions at the Vehicle Intelligence Marketplace during the CES in Las Vegas (January 6-9, 2015).

Figure 2 On the Las Vegas Strip, a Bosch vehicle demonstrates how the traffic jam assist function works. In congested traffic up to a speed of 60 kph, the function brakes, accelerates, and keeps the vehicle in its lane – without any intervention by the driver.

As one of the world’s largest providers of mobility solutions, Bosch has been working on automated driving since 2011 at two locations – Palo Alto, California, and Abstatt, Germany. The teams at the two locations can draw on a worldwide network of more than 5,000 Bosch engineers in the field of driver assistance systems. The motivation behind the development at Bosch is safety. Worldwide, an estimated 1.3 million traffic fatalities occur each year, and the numbers are rising. In 90 percent of cases, human error is the cause.

Figure 3 Thanks to the traffic jam assist, drivers can now reach their destination more safely and with less stress. Driving along the Las Vegas Strip in a demonstration vehicle, drivers can see for themselves what the function is capable of.

From predictive emergency braking to traffic jam assistance

Assisting drivers in critical traffic situations can save lives. Studies suggest that, in Germany alone, up to 72 percent of all rear-end collisions resulting in casualties could be avoided if all cars were fitted with the Bosch predictive emergency braking system. Drivers can also reach their destinations safely and with minimum stress using the Bosch traffic jam assistant. At speeds of up to 60 kilometers per hour, the assistant brakes automatically in heavy traffic, accelerates, and keeps the car in its lane.

Figure 4 As one of the world’s largest providers of mobility solutions, Bosch has been working on automated driving since 2011. Cars equipped with Bosch technology can already drive themselves in certain situations, such as traffic jams or when parking.

“With driver assistance systems, Bosch expects to generate sales of one billion euros in 2016,” Hoheisel says. Assistance systems are the cornerstone for automated driving, which will become established in a gradual process. Bosch already has its sights on highly automated driving, in which drivers no longer have to constantly monitor the vehicle. “With Bosch highway pilots, cars will be driving automatically on freeways by 2020, from entrance ramp to exit ramp,” Hoheisel predicts. In the decade that follows, vehicles driving fully automated will be available, capable of handling any situations that arise.

Figure 5 Bosch is developing and testing automated driving at two locations – in Palo Alto, California, and Abstatt, Germany. The teams at the two locations can draw on a worldwide network of more than 5,000 Bosch engineers working in the field of driver assistance systems.

Bosch sensors are the car’s eyes and ears

Automated driving affects every aspect of the car – powertrain, brakes, steering – and requires comprehensive systems expertise. It is based on sensors featuring radar, video, and ultrasound technology, sensors Bosch has been manufacturing by the millions for many years. “Sensors are the eyes and ears that let vehicles perceive their environment,” Hoheisel says. Powerful software and computers process the collected information and ensure that the automated vehicle can move through traffic in a way that is both safe and fuel efficient.

As vehicles gradually take over more and more driving tasks, safety-critical systems such as brakes and steering must satisfy special requirements. Should one of these components fail, a fall-back is needed to ensure maximum availability. Bosch already has such a fall-back for brakes: the iBooster, an electromechanical brake booster. Both iBooster and the ESP braking control system are designed to brake the car – independently of each other – without the driver having to intervene.

Figure 6 Bosch has been testing automated driving with special demonstration vehicles on public roads in the U.S. and Germany since the beginning of 2013. Several thousand test kilometers have already been driven.

iBooster: essential for automated driving

In this way, the Bosch iBooster meets an essential requirement for automated driving. The brake booster can build up brake pressure independently, three times faster than an ESP system. If the predictive brake system recognizes a dangerous situation, the vehicle stops much faster. At the same time, the iBooster can also provide the gentle braking required by the ACC adaptive cruise control, all the way down to a complete stop. Moreover, it is practically silent.

Figure 7 The motivation behind the development of automated driving at Bosch is safety. Worldwide, an estimated 1.3 million traffic fatalities occur each year. Drivers can reach their destinations safely and with minimum stress using systems such as the Bosch traffic jam assistant. At speeds up to 60 kilometres per hour, the assistant brakes automatically in heavy traffic, accelerates, and keeps the car in its lane.

The iBooster is also a key component for hybrid and electric cars. One reason is that it does not require a vacuum, which otherwise has to be generated in a complex process by the combustion engine or a vacuum pump. Second, because in conjunction with ESP hev (designed especially for hybrid and electric vehicles), the brake booster can recover nearly all braking energy and convert it into electricity, which extends the e-vehicle’s range. Thanks to the iBooster, nearly all typical traffic delays can be used to recover maximum braking energy for the hybrid or electric vehicle’s electric motor. If the car has to brake sharply, or if the generator is unable to provide the necessary brake torque, the brake booster generates any additional brake pressure required in the conventional way, using the brake master cylinder.

Figure 8 Driver assistance systems are the cornerstone of automated driving, which will become established in a gradual process. Bosch has already set its sights on highly automated driving, in which drivers no longer have to constantly monitor their vehicle. With the Bosch highway pilot, cars will be driving themselves on freeways by 2020, from entrance ramp to exit ramp. In the decade that follows, vehicles will become fully automated, capable of handling any situations that arise.

Bosch technology at the Vehicle Intelligence Marketplace

At 2015 International CES in Las Vegas, Bosch will not only be presenting its extensive product portfolio for driver assistance functions and braking systems at the Vehicle Intelligence Marketplace. The company will also be exhibiting a true Hollywood legend: K.I.T.T. replica from the action series “Knight Rider”.

Additional links:

www.automated-driving.com

YouTube: http://bit.ly/1osJDai

Motor Control Tutorial

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This is a tutorial for beginners to motor control design. The tutorial describes motor types and demonstrates signal control strategies through graphical animations. The tutorial also provides descriptions and schematics for basic motor control power semiconductor topologies.

It is supplied by Freescale semiconductors and is aimed a design engineers but is also good background for us top technicians!

http://www.freescale.com/webapp/sps/site/training_information.jsp?code=WBT_MOTORCONTROL_TUT#

How do I measure… everything from voltage to the speed of light

Tom Denton2 Comments

Here is a selection of some interesting and fun information about measurement from my favourite ‘scope’ company Pico. Visit the site to see more.

Tom

How do I measure… everything from voltage to the speed of light

How Do I Measure…

Our oscilloscopes and data loggers are capable of measuring a large variety of measurements — everything from voltage to the speed of light.

Select the type of measurement you want to make from the drop-down list below and find out how you can measure it using Pico products.

how do I measure… 4-20 mA  signals acceleration audio signals automotive signals battery discharge current flow food temperature frequency humidity light level liquid level output of a dynamo oxygen in air pH pressure rainfall resistance sound level speed of a car speed of light speed of sound strain, force and load temperature the beating of a bird’s wing the swing of a pendulum video signals voltage wet bulb globe temperature (WBGT)

4-20 mA  Signals

Pico products for measuring 4-20 mA  signals

Pico has several products suitable for measuring and recording 4-20mA signals, but the input circuit has to be slightly modified.

shunt resistor

A simple shunt resistor can be used to convert the current in the loop to a voltage that is suitable for the ADC to measure. A 250 ohm resistor will give a voltage output of 1 to 5 V. This method can be used in systems where the signal can be grounded.

Other resistor values can be calculated using the formula below:

Rb = Vmax / Imax

where Vmax is the maximum input voltage of the ADC, Imax is the maximum measured current and Rb << Rin.

Other information

Pico has four products where this resistor can easily be placed on a terminal board:

Acceleration

Pico products for measuring acceleration
  • PicoScope 4224 Oscilloscope: The most popular product for measuring acceleration. Most moving-coil and piezo sensors can be plugged directly into the PicoScope. Silicon sensors are often 10 V bridge-type sensors that require a 10 V excitation voltage and produce a millivolt output. An additional precision 10 V power supply is required when using silicon sensors with Pico products.
  • PicoScope 4224 IEPE Oscilloscope: The ideal instrument for use with a phantom-powered accelerometer, as it has a built-in IEPE power output. Just plug in the accelerometer and use like a normal scope. We can supply a suitable accelerometer — the TA095 — with a ±50 g measurement range.
Other information

There are several types of accelerometer:

Piezo resistor

A piezoresistive sensor uses a piece of material whose resistance changes when it is compressed, attached to a weight. When the weight is accelerated, it exerts a force on the piezoresistor. If a constant current is passed through the piezoresistor, the voltage changes. Current is about 4 to 8 mA and voltage is 8 to 24 V. Typical sensitivity is about 100 mV/g over the range 0 to 50 g. This type of sensor responds to frequencies up to 10 kHz.

Piezoelectric

A piezoelectric sensor generates charge when it is accelerated: typically 50 pC per g. It is necessary to integrate the charge to give a voltage which is related to the acceleration: this means that it is not suitable for low-frequency work, but piezoelectric sensors respond to frequencies up to 30 kHz.

Silicon bridge

A silicon bridge sensor is a piece of silicon that has been etched to leave a block of silicon at the end of a beam. When subjected to acceleration, the block exerts a force on the beam and the resistance of the beam changes. Maximum frequency is about 5 kHz. The sensor is a bridge, and so it requires an excitation signal of 5 to 10 V. Temperature compensation is required.

Micromachined silicon

Micromachined silicon accelerometers are a form of differential capacitor. One of the advantages of this type of sensor is the ability to measure DC acceleration (and consequently tilt). The maximum frequency is about 1 kHz. The popular Analog Devices ADXLxxx range of single and dual-axis sensors have built-in signal conditioning circuits that produce a voltage output suitable for use with our data loggers and oscilloscopes.

Voice coil

Voice coils work on the same principle as microphones, hence the name.

Audio Signals

Pico products for measuring audio signals

For measuring high-quality audio signals and for audio spectrum analysis the PicoScope 4000 Series precision oscilloscopes are ideal. For less demanding applications, the lower cost PicoScope 3000 Series can also be considered.

Other information

The PicoScope software includes common audio measurements such as THD, SINAD and SFDR. It is included with all our oscilloscopes and data loggers.

We also have the following application notes on audio measurement:

Automotive Signals

Please visit our automotive diagnostics website for more information.

Battery Discharge

Pico products for measuring battery discharge

Pico has several products suitable for recording battery discharge. They all connect to a USB port on the computer.

  • PicoLog 1012: This 12 analogue input channels. The input voltage range is 0 to 2.5 V and the resolution is 2.5 mV. This device is suitable for measuring multiple channels at higher speed.
  • PicoLog 1216: This has 16 analogue input channels. The input voltage range is 0 to 2.5 V and the resolution is 625 µV.
  • ADC-20: This has 8 single-ended or 4 differential high-resolution analogue inputs. The input voltage range is -2.5 V to +2.5 V and the resolution is about 5 µV. This device should be used if more precise measurements are required at a slower speed.
Other information

Terminal connector boards are available for the PicoLog 1000 Series and ADC-20 data loggers.

We also have the following application note on battery discharge:

Current

Pico has several products suitable for measuring and recording current.

The Pico range of current clamps allow current to be measured without having to break into the circuit. All of them can be used with any of our data logging or oscilloscope products:

Current Monitoring kit

The Pico Current Monitoring Kit contains current clamps, power monitor, data logger and everything else you need to start logging currents from up to three separate circuits. It is ideal for measuring and balancing 3-phase power supplies as well as machine monitoring and energy efficiency studies.

shunt resistor

For small currents, a simple shunt resistor can be used to convert the current into a voltage, which the ADC can then measure. This can be done providing the signal can be grounded.

The resistor value can be calculated using the formula below:

Rb = Vmax / Imax

where Vmax is the maximum input voltage of the ADC, Imax is the maximum measured current and Rb << Rin.

WARNING: This method is NOT suitable for monitoring mains currents.
To monitor mains currents with data acquisition or oscilloscope products, use a current clamp.

Pico has four products where this resistor can easily be placed on a terminal board:

Flow

There is a wide variety of flow sensors that can be used with Pico products.

Flow is commonly sensed by measuring differential pressure across two points in a pipe. This can be done using the Venturi effect (by placing a restriction in the flow). An alternative approach is to use a Pitot tube. The main advantage of this type of approach is that disturbance of the flow can be kept to a minimum. One disadvantage is that two holes are usually required in the pipe, making cleaning difficult. Also be aware that many differential pressure sensors are intolerant to aggressive gases and chemicals. The method for measuring these sensors is described in the section on pressure sensors.

For applications where pipes regularly need cleaning, consider using a bending vane type of sensor. As the name suggests, this consists of a vertical vane that deflects as flow increases. This deflection is measured using a strain gauge. The method for measuring such sensors is covered in the section on strain.

‘Paddle wheel’ sensors rotate in proportion to flow. The rotation is detected by either optical or magnetic means. These sensors produce a pulsed output. The main advantage of such sensors is low cost, and some are also suitable for measuring aggressive gases and liquids. The main disadvantage is disruption to the flow. For information on interfacing to such sensors, see measuring frequency.

Ultrasonic and magnetic flow sensors allow flow to be measured with no moving parts. This minimises (or eliminates) disturbance to flow and provides for increased reliability. The main disadvantage is cost. These sensors tend to have built-in signal conditioning with either voltage or 4 to 20 mA current loop outputs.

Frequency

Pico products for measuring frequency

Many Pico products can be used to measure frequency. The choice of device is dependent on the frequency range, the voltage input range and the number of channels required.

There are four possible measurement requirements:

  • Logging frequency variations over time:
    PicoLog can be used to record fluctuations in frequency over time.
  • Measuring spot frequencies:
    PicoScope’s automatic measurements can be used to take spot frequency measurements and to show variation statistics.
  • Investigating the frequency components of a signal:
    PicoScope’s spectrum analyser shows the frequency spectrum of a signal, allowing the measurement of any frequency component within the signal.
  • Viewing frequency variations over time:
    When used with the PicoScope 4000 Series 12-bit scopes, PicoScope can be used to graph fluctuations in frequency over time.

Oxygen in Air

The DD103 oxygen sensor can be connected to the external sensor sockets on the DrDAQ Data Logger to measure oxygen in air.

Unlike previously available oxygen sensors, the DD103 oxygen-in-air sensor can measure the full 0 to 100% range. This makes it ideal for many chemistry, biology and physics experiments.

pH

Pico products for measuring pH

ph probe connection circuit

The DrDAQ Data Logger has a dedicated pH input. Optional pH electrodes are also available. DrDAQ measures pH over the full 0 to 14 range with a resolution of 0.02 pH.

Despite the low cost of DrDAQ, options are provided for calibration and temperature compensation, allowing very accurate pH measurements.

The circuit on the right allows any of our oscilloscope and data logging products to monitor signals from pH probes. The op-amp needs to have a very high input impedance — an LT1114 is suitable.

Pressure

Most pressure sensors are ‘10 V bridge’ type that require a 10 V excitation voltage and produce millivolt outputs. An additional precision 10 V power supply is required to provide this excitation voltage when using this type of pressure sensor with any of our products.

Note that some pressure sensors have signal conditioning built in. These sensors usually have a voltage output or a 4-20 mA output. See the appropriate sections in this guide for information on measuring these signals.

Resistance

Pico products for measuring resistance

Pico has two products that can be used for measuring and recording resistance:

Other information

Other Pico products can also be used to monitor resistance. This is achieved using a precision voltage reference and a known resistance. The two resistances are connected in series and fed by the precision voltage source. The voltage developed across the unknown resistor can then be measured and used to infer the resistance.

Pico has two products where the resistors and voltage source can easily be placed on a terminal board:

  • ADC-20 with terminal board: can monitor 8 channels with high accuracy.
  • PicoLog 1000 Series with terminal board: can monitor 12 or 16 channels at higher speed.

Sound Level

Pico products for measuring sound level
  • The DrDAQ Data Logger has a built-in microphone that can directly measure sound level over the 55 to 100 dB range. The low cost of DrDAQ makes it ideal as either a sound-level meter or sound-level data logger.
  • PicoScope 4224 IEPE Oscilloscope: The ideal instrument for use with a phantom-powered,calibrated microphone, as it has a built-in IEPE power output. Just plug in the microphone and use PicoScope like a normal scope.

Speed of a Car

One of our series of educational technical notes, this experiment looks at measuring the speed of a car. (Unfortunately due to budget restrictions a rather small car had to be used!)

Speed of Light

This topic is covered in the science experiment “Measuring the Speed of Light”.

Speed of Sound

This topic is covered in the science experiment “Measuring the Speed of Sound”.

Strain, Force and Load

The strain gauge is perhaps the most popular sensor for measuring force and deflection. As a strain gauge is stretched or compressed, its resistance changes. By mounting the strain gauge on a calibrated carrier, force can be indirectly measured. Such a sensor is commonly referred to as a load cell. Load cells consist of one or more strain gauges configured in an industry-standard ‘10 V bridge’ arrangement. Sensitive load cells are used in weighing scales, while at the other extreme heavy industrial load cells can be used to measure loads of several tonnes.

As mentioned, most load cells are ‘10 V bridge’ types that require a 10 V excitation voltage and produce millivolt outputs. An additional precision 10 V power supply is required to provide this excitation voltage when using this type of pressure sensor with any of our products.

Temperature

Temperature is the most commonly measured real-world signal. We have several products dedicated to measuring temperature. In addition, if you wish to monitor a mix of temperatures and other parameters, our data logging products provide a simple plug-and-play solution.
Other information

We also have the following application notes available:

See also:

Voltage

The majority of Pico products can be used for measuring voltage. To ensure you choose the correct product you must consider the following:
  • How many voltages (channels) need to be measured
  • How big (or small) are the voltages
  • How fast the signals change
  • How long you wish to record the voltage for
How many voltages (channels) need to be measured

If your requirement is to measure a large number of channels, then consider the PicoLog 1012 (12 channels) or the PicoLog 1216 (16 channels). If more channels are required then it is possible to use multiple ADC units on the same PC to give very high channel counts. If you have a number of voltages to record over a wide area, then the EnviroMon networked data logging system can measure up to 30 channels per logger.

How big (or small) are the voltages?

Most of our data logging products have fixed input ranges (2.5 V or 5 V). These can be easily increased through the use of simple potential divider circuits. Our oscilloscope products have software selectable ranges (10 mV to 100 V).

If you wish to measure high voltages then the range of our oscilloscope products can be extended to 1000 V using suitably rated x10 scope probes. For higher voltages, and high-current supplies such as mains (house current), we recommend the use of one of our oscilloscope products with an isolating x100 differential scope probe.

If you wish to measure small voltages, you need to consider the input range of the device and also the resolution.

If your signals have frequency components above 1 kHz then consider our oscilloscope products. If all your signals are lower than 1 kHz you can use either our data logging or oscilloscope products.

How long you wish to record the voltage for

If you wish to record voltages for long periods of time (more than say 5 minutes), then use one of our data loggers or, if you need a stand-alone system, use EnviroMon.

 

Pico Technology — for all your oscilloscope and data acquisition needs

How do I measure… everything from voltage to the speed of light