Back-Lighting with LEDs

Liquid crystal displays require back-lighting. This is because liquid crystal displays do not generate any light, and their visibility depends on light passing through the display. Opaque sections in the display become visible when they block light from behind the display. To make the display readable, manufacturers resort to providing them with light from behind the display.

The back-lighting in liquid crystal display panels may come from sources like incandescent, fluorescence, electroluminescence, woven fiber optics, or LEDs. Appearance, cost, and features consideration decide the ultimate choice for the selection of source for the back-lighting. The most popular is solid-state lighting using LEDs, as these devices offer better luminance and power efficiency, as compared to all other sources. Another advantage of LED back-lighting for LCD panels is the long life of LEDs.

Earlier, LED back-lighting typically used direct lighting, with large numbers of LEDs mounted behind the display. This arrangement provided excellent image quality along with the ability of local dimming. However, the high cost of this method did not allow it to gain market share. Rather, back-lighting technology changed over to edge-mounted LED back-lighting. An added advantage of edge-mounted LED back-lighting was that the edge-lit LCD panels could be made in extremely thin designs.

By using edge-lit LED back-lighting, manufacturers could reduce the number of LEDs necessary, by concentrating them along the edges. Initially, manufacturers used LEDs on all four edges. Very soon, they placed the LEDs along two shorter edges only, and eventually, they were placing the LEDs on only a single short edge of the LCD panel.

LEDs are a good choice for back-lighting. They are compact, operate in a wide temperature range, offer a good color selection, have a low operating voltage, and have a long operating life of at least 50 thousand hours. Over a specified range of drive current levels, LEDs offer a predominantly fixed voltage drop. However, LED back-lighting also offers some challenges. For instance, the light provided by the LEDs is uneven, which improves with a suitable light pipe or diffuser. Another challenge is the current through the LEDs depends on the ambient temperature, and requires close monitoring to allow safe operation over a wide range of temperatures.

The driver for such constant-current devices requires building up the drive voltage until it is supplying the desired current level. It reaches a stabilization point when the drive voltage equals the sum of the forward drops of all the LEDs in series. The maximum voltage of the driver limits the number of LEDs in series that it can drive at a time. However, even the simplest of drivers requires holding some voltage in reserve, for dropping across a current limiting resistor. This means a driver will never be able to apply the entire power supply voltage across a chain of LEDs.

The number of LEDs required depends on the size of the LCD panel, and its brightness. High-brightness and ultra-high-brightness LCD panels require a larger number of LEDs. Driving large numbers of LEDs requires sophisticated constant current drivers and high-efficiency power supplies.

Controlling BLDC Motors in Trapezoidal Form

One of the easiest motor control methods for brushless DC motors is the trapezoidal, six-step, or 120° block commutation control. Optimum torque generation requires applying square-wave currents to motor phases in alignment with the trapezoidal back-EMF profile of BLDC motor. MOSFETs of the inverter drive can exhibit only six combinations of on/off states. Therefore, this method has another name—the six-step—resulting in six possible orientations of the stator field within the plane of rotation of the magnetic field of the rotor.

Depending on the desired direction of rotation of the motor, the six possible inverter states must follow a specific sequence. This is necessary so that the orientation of the stator and rotor magnetic fields produces the maximum torque. There are two ways of sensing the rotor position for determining proper commutation timing—sensing through Hall-effect sensors on the motor, or a sensorless way of back-EMF sensing of the rotating motor phases.

Of the two, using sensors requires no voltage or current feedback signals for proper operation. Rather, the position feedback from the Hall sensors is adequate to determine the proper sequence for energizing the motor phases. Hall sensors in strategic positions in the motor can sense rotor position as a result of the rotating magnetic field of the permanent magnets in the rotor. Trapezoidal control using sensors is easier to implement, as it allows for proper commutation even during startups—the information about the rotor position is available even at zero speed.

For trapezoidal control without sensors, the proper motor commutation sequence depends on the back-EMF that the motor’s rotation generates. Such trapezoidal control requires energizing only two motor phases at a time. As the non-energized phases have no current flowing through them, it is possible to sense the back-EMF they are producing during the non-energized times. Typically, such back-EMF positional feedback in BLDC motors is trapezoidal and is either linearly increasing or decreasing. Therefore, most positional feedback techniques using back-EMF use a zero-crossing detection for determining the moment when it crosses a reference point. This can be either half the DC bus voltage or the neutral motor voltage.

Sensorless control has a major drawback. As the magnitude of the back-EMF is proportional to the rotational speed, the rotor must be rotating at a minimum speed to generate a back-EMF of adequate magnitude for sensing the rotor position properly. Therefore, it is necessary to use a startup mechanism for kick-starting the motor until it reaches an adequate rotational speed.

Although it is easier to implement a trapezoidal control with sensors, the Hall sensors add an increased cost. Additionally, signals from Hall sensors may be noisy and may require hardware or software filtering. The motor also requires more wiring, which in some environments, may be a challenge. On the other hand, sensorless control is more complex. It is necessary to tune it to meet specific loads or operating conditions and may face difficulties in starting up under heavy loads. That makes sensorless control well-suited for applications with a well-known load profile that increases with speed, such as for a fan.

What are RTDs?

RTDs or Resistance Temperature Detectors are the simplest way to measure temperature. RTD sensors work on the principle that a metal’s electrical resistance changes with temperature. For instance, the electrical resistance of pure metals typically increases with an increase in temperature, that is, they exhibit a positive temperature coefficient. RTDs operate over a huge temperature range, starting from -200 °C, right up to +850 °C. They offer excellent long-term stability, high accuracy, and repeatability.

An RTD sensor, being a passive device, does not produce a signal by itself. An electronic circuit is necessary to send an excitation current through the sensor. This produces a voltage across the RTD, proportional to the excitation current and the resistance of the RTD. Further electronic circuitry amplifies the voltage across the RTD and delivers it to an analog-to-digital converter, whose output produces a digital output, a representative of the temperature of the RTD.

The electronics in an RTD circuit have some basic trade-offs. For instance, the excitation current must be small enough to prevent self-heating in the RTD element. Any excitation current produces Joule or I2R heating in the RTD. This self-heating effect can raise the sensor’s temperature to a value higher than that of the environment that the RTD is measuring. By keeping the excitation current low, it is possible to keep the self-heating low to a great extent. Moreover, the amount of self-heating also depends on the medium surrounding the RTD sensor, and how effectively it allows heat to accumulate. For instance, placing the RTD element in still air produces a more pronounced self-heating effect than immersing it in moving water.

System noise, offsets, and drift of different system parameters also affect the minimum detectable change in temperature. Therefore, the RTD voltage must be large enough to overcome them. As the excitation current must be low enough to prevent self-heating, it is necessary to use an RTD sensor with sufficiently large resistance, so that it will produce a relatively large voltage. Although it is necessary to use a large RTD resistance to reduce measurement errors, it is not advisable to arbitrarily increase the resistance. This is because a large RTD resistance leads to an increase in the response time.

Theoretically, any metal should work for constructing an RTD. In fact, Siemens used copper wire for constructing the first RTD in 1860. However, he soon discovered that by using platinum, he could produce RTDs that were more accurate over a wider temperature range.

Precision thermometry typically uses platinum RTDs as the temperature sensor. This is because platinum has a linear resistance-temperature relationship, higher repeatability, and a wider temperature range. Moreover, platinum does not react with most of the contaminant gases in the environment. However, the industry also uses two other materials for making RTDs: nickel and copper. Among the three metals, copper offers the highest linearity and the lowest cost. However, as copper has the highest conductivity of the three, it offers a lower resistance. A copper RTD, therefore, produces a relatively lower voltage and can be difficult to use for measuring small temperature changes.

What is Thermorite?

Kemet has developed and patented a type of ferrite material that is sensitive to temperature. They use this material to make various types of thermal sensors. The electronic industry uses thermal sensors and switches for monitoring temperature and maintaining various applications in stable modes of operation. A reed switch inside the thermal sensor makes or breaks the current flow.

Kemet offers three basic types of thermal sensors. The first type is a Kemet sensor using a reed switch inside a thermos-ferrite body. The second type is a thermal sensor using a bi-metal switch. The third type is thermistors.

The Kemet thermos-ferrite and reed switch combination works by sensing the temperature of the surrounding environment. The thermos-ferrite has a curie point and as the temperature crosses this curie point, the magnetic reed switch switches on or off.

The bi-metal switch contains two metal plates that have different thermal expansion coefficients. As the temperature changes, the two metals deform and disconnect at a particular temperature.

Thermistors are semiconductor sensors and may have a negative temperature coefficient (NTC) or a positive temperature coefficient (PTC). They change their resistance in accordance with changes in temperature.

Thermorite is a ferromagnetic material with soft magnetic characteristics when under curie temperature. As the temperature goes up, the saturated magnetic flux density of the material decreases, and the material becomes paramagnetic. That is, the material loses its magnetic property rapidly as its temperature reaches the curie point, becoming close to zero. Time does not affect curie temperature as it is a function of the compounding ratio of the material. That means Kemet can make Thermorites with different curie points by changing the material’s permeability.

Kemet offers two types of thermos-ferrite thermal sensors—the Break type and the Make type. The Break type thermal sensors consist of a reed switch surrounded with a Thermorite jacket around the switch part and two permanent magnet cylinders on each end. The Break type switch remains ON when the operating temperature is lower than the trigger temperature. The switch opens as the temperature rises and reaches the trigger temperature or crosses it. When the temperature goes down, the switch closes again only when the temperature goes below the recovery temperature.

When the temperature is below the trigger temperature, the Thermorite jacket is magnetic, and it generates an annular magnetic field. The magnetic field induces the N tip and the S tip of the reed switch to touch due to magnetic attraction. This turns the switch to its ON position. As the temperature rises and reaches the trigger temperature, the Thermorite jacket loses its magnetic flux. This allows the tips of the reed switch to pull apart, and the switch turns OFF.

Construction of the Make type thermal switch is similar to the Break type. The only difference is the former has two Thermorite jackets with a gap in between. The two Thermorite jackets create annular magnetic fields when the temperature is below curie point. This causes the reed switch poles to stay apart, and the switch remains OFF. As the temperature rises to the curie point, the Thermorite jackets lose their magnetic flux. This allows the two reed switch tips to close, and the switch turns ON.

What is the Pyroelectric Effect?

With the electronic industry trending more toward automated devices, their safety and reliability are assuming the utmost importance. Pyroelectric sensors help to make these devices work properly, by indicating changes that require specific types of reactions. Many types of ceramic materials can absorb infrared rays and generate an electrical signal in response.

Certain crystalline materials demonstrate Pyroelectricity. These materials, which are electrically polarized, demonstrate a change in their polarization when they undergo a change in temperature. The change in polarization of the crystal material generates a temporary but detectable voltage across it. Different materials exhibit differences in pyroelectric coefficients that show their sensitivity to temperature.

Infrared radiation heats pyroelectric ceramic crystals to generate a detectable voltage. It is possible to detect the infrared rays the object is generating by using passive infrared sensors. The sensor can detect the wavelengths that the pyroelectric ceramic crystal absorbed when it is in position between the hot object and the sensor. Pyroelectricity has several applications.

Motion Sensors—Typically, there are two types of infrared motion sensors, active and passive. Active infrared sensors have a long range of operation, and the emitter and sensor can be far apart. A garage door safety sensor is a good example of an active sensor. Anything blocking the infrared beam across the opening of the garage door generates a signal to prevent the garage door from moving.

Passive infrared sensors can also detect motion by sensing infrared radiation or heat direct from a source. Such sensors can detect the presence, or absence, of an object emitting heat, such as a human body.

Pyroelectric motion sensors can be surface-mount devices and are highly sensitive. Manufacturers offer them in single-pixel configuration or as a 2×2 pixel configuration, allowing users to determine the direction of the motion it has detected. The sensors have a high dynamic range and a fast response time that ensures rapid and accurate motion detection.

Gas Sensors—Infrared pyroelectric sensors can detect and monitor gases. In fact, this is one of their most popular applications. The sensors operate by directing infrared radiation from an emitter through a sample of the gas. The detector senses if a certain IR wavelength is present on the other side. If the sensor does not detect that wavelength, it means the gas that absorbs this wavelength is present in the sample. Optical IR filters allow fine-tuning the sensor to a specific wavelength, thereby permitting only the desired wavelength to pass through to the sensing element.

Pyroelectric gas sensors are available in small SMD packages and most have a digital I2C output, although analog outputs are also available. The sensor consumes very low power but offers high sensitivity and extremely fast response times.

Food Sensors—Similar to gas sensors, infrared pyroelectric food sensors can detect food-related substances like sugar, lactose, or fat. These are typically general IR spectroscopy sensors for monitoring commercial, medical, or industrial substances or processes.

Flame Sensors—With pyroelectric elements, it is easy to construct sensors for detecting flames. As flames are strong, flame sensors, apart from detecting the presence of the flame, can also discriminate the source of the flame. Typically, they compare three specific IR wavelengths and their interrelated ratios. This allows them to detect flames with a high degree of accuracy.

MEMS Vibration Sensor

Analog Devices Inc. has unveiled their MEMS or Micro-Electro-Mechanical System-based accelerometer technology at the Sensors + Test Conference in Nuremberg, Germany. The MEMS vibration sensor can track vibrations at frequencies of 22 kHz. This is especially helpful for sensing high-frequency vibrations in industrial equipment.

The MEMS technology from Analog Devices is unique in the sense that it uses two MEMS mechanisms placed beside each other. The arrangement helps to cancel out common mode noise, favoring only the differential mode noise. Vibration and shock sensors from ADI are small format sensors that enable equipment designers to build vibration-detection chips within devices for industrial process-control, rather than as add-on modules.

Most vibration sensors today are piezo-electric-based modules. They have two disadvantages—it is not possible to mass-produce them, and their range is limited to 5-kHz frequencies. On the other hand, ADI makes their accelerometers in CMOS processing lines, and they can mass produce them easily. Additionally, ADI can undercut the prices of piezo-based vibration sensors by about 50 percent. For instance, the prices of ADI vibration sensors are around $35 as opposed to piezo-based sensors at $70.

With manufacturers looking for whatever they can get for improving the production and efficiency of their equipment, MEMS vibration sensors from ADI are the right products in the right place and at the right time. Although, when comparing unit shipments, the industrial market is small compared to the consumer electronics market, revenue-wise, the former is incredibly important and offers better margins. MEMS sensors address identified needs within the industrial market sector, and therefore, provide tangible value.

In the case of piezo-based vibration sensor modules, the standard practice is to bolt them onto the side of vibrating industrial equipment. However, using the chip-based accelerometer sensor from ADI is simpler, as it is possible to integrate it right within the circuit board of the device when assembling. ADI is of the opinion that some piezo-based vibration sensor manufacturers may retrofit MEMS chips into their bolt-on modules. However, ADI also expects OEMs of industrial equipment to stop using modules and rather start integrating ADI MEMS chips directly into their pumps, motors, gearboxes, and other pieces of industrial equipment.

Industrial equipment manufacturers are increasingly using vibration sensors as these can sense on-coming failure before it happens. For instance, a deteriorating bearing will vibrate at high frequencies before it fails. As it nears failure, its vibrating frequencies will drop until it finally disintegrates totally, possibly causing damage to the rotor. This is why predictive maintenance is increasingly becoming popular.

The present trend in the industry is to move towards predictive maintenance from preventive maintenance. Early detection through predictive maintenance can cut down repair costs by as much as 25 percent. Waiting to repair equipment until something fails can push up the maintenance costs more than ten times. Compared to other predictive maintenance techniques such as ultrasonic analysis or infrared thermography, vibration analysis offers better return-on-investments, by as much as three times.

ADI offers its vibration and shock sensors in ceramic packages, available in 70g, 250g, and 500g ranges.

Types of EV Connectivity

Technologies related to EVs or electric vehicles are undergoing enormous research and development efforts with the ultimate aim of achieving widespread EV adoption. Although at present, extending the driving range is occupying much of the direction of this effort, future benefits will ultimately extend beyond progressive battery and charging technologies.

For instance, for future EVs, there are exciting value propositions like the number of different connectivity technologies they will be featuring. This is the V2X or vehicle-to-everything connectivity that includes in-use technology like V2G or vehicle-to-grid, V2N or vehicle-to-network connectivity, and the emerging technology like V2V or vehicle-to-vehicle, which engineers expect will change the future working of EVs.

The recent production of EVs includes V2G or vehicle-to-grid connectivity. This refers to the EV’s ability to allow electricity to flow bidirectionally from the vehicle to the grid and back. The concept is that the batteries in the EV, being relatively large, can not only act as energy storage for the vehicle but also as energy storage for the grid and as V2H, energy storage for the home.

V2G, therefore, relies on a power electronics technology, bidirectional charging. Such an EV requires a versatile power conversion and control circuit, allowing conversion between the AC of the grid and the DC of the battery. There are innumerable benefits of V2G for both the vehicle owner and the grid.

The owner can use the EV not only as a vehicle but also as a backup generator for home use in case of a disaster like a blackout. The vehicle owner can offset their cost by selling excess energy in their EV to the grid.

For the infrastructure of the grid, V2G technology can supplement the grid stress when the demand is at its peak. During low demands, or when the energy generation is higher, the grid can recharge the EV.

V2N is another type of EV connectivity, and it refers to the ability of the vehicle to connect to the Internet and communicate with anything else on the network. This mostly refers to the vehicle connecting to the internal network and cloud service of its manufacturer. This allows the manufacturer to closely monitor the vehicle, update it dynamically, and thereby, ensure maximum performance.

Companies use V2N connectivity for extracting information related to performance from their vehicles. They gather metrics such as battery charge cycles, energy throughput, and range. With such feedback information from all vehicles connected to the V2N network, EV manufacturers conduct statistical analysis for understanding the real-time operating conditions of their vehicles and improve their performance. V2N-connected vehicles can also receive necessary updates for their software and firmware for introducing performance improvements.

However, V2V connectivity will bring the biggest impact of all these, although, currently it is far from being a reality. This connectivity is the interconnection of all connected vehicles on the road. V2V allows all vehicles to wirelessly communicate between themselves, information like position, speed, road conditions, and other important driving information. V2V-enabled vehicles can also share real-time road and traffic condition information for achieving the optimal path to their destination.

3D Printed PCBs

The world over, electronics manufacturers are facing difficulty with supply disruption. Those struggling with circuit board production are trying out a new and innovative method for solving their problems. They are using 3D printers for making printed circuit boards. Not only are these boards faster to make as compared with traditional production methods, but they are also more versatile. Moreover, this method provides significant cost savings, and it can produce more complex circuits also.

The biggest advantage of 3D printed PCBs is that manufacturers can control their circuit board supply. They can eliminate disruptions from shipping slowdowns, plant shutdowns, or other geopolitical maneuverings. All these have been stretching circuit board supply chains to their breaking point while leaving manufacturers to look for alternatives frantically.

At present, this technology is in its nascent stages and requires more R&D to scale it to large-scale production levels. However, manufacturers are finding 3D printing of producing printed circuit boards in-house a viable alternative for validating iterations and gaining practical intuition that would take a long time by outsourcing fabrication. This is especially helpful in rapid prototyping, small-scale production, and making unique electronic products.

Manufacturers have been making rapid advancements in this technology. They have successfully disrupted traditional methods of PCB manufacturing, thereby accelerating the speed to market for their newer products. For instance, Optomec, a 3D printer manufacturer, claims its semiconductor solution has helped increase 5G signals by 100%.

Whereas traditional methods of fabricating PCBs can take days or weeks to produce, 3D printers can do the job within 30 hours. Another significant factor is design freedom, as compared to the traditional rectangular board, 3D printers can create more complex shapes, including flexible boards, boards with honeycomb structures, and even boards with three-dimensional structures. For some applications, it is possible to use a common desktop printer with conductive filaments.

There are two ways to fabricate printed circuit boards with 3D printers. The first method uses conductive materials to print the circuitry directly. The other makes circuit boards with hollow channels that the user fills with conductive materials.

3D printers construct the printed circuit board entirely through additive manufacturing. This is different from the traditional methods of etching or CNC milling that remove unwanted material to retain conductive traces.

Most 3D printers are capable of handling conductive printing materials. These 3D PCB printers actually lay down a path of conducting material to form the circuitry. These materials may be inks or filaments with conductive particles infused in them. The conductive material may be graphite, copper, or silver. It is also possible to spray these materials as an aerosol-laden stream.

Commercial 3D PCB printers can also use inks as an option. These are similar to 2D printers, and deposit droplets of insulating and conductive inks to build the circuitry. While some printers are capable of printing the entire board including the substrate, others need a prefabricated substrate board. The former can fabricate complex, multi-layered circuit boards that contain embedded components like LEDs, resistors, and inductors. One example of such a 3D printed board is a 10-layer high-performance structure with components on both sides.

Underwater, Battery-less, Wireless Camera

At the Massachusetts Institute of Technology, engineers have built a wireless camera that does not require a battery to operate underwater. The necessity arose when scientists wanted to observe life under the oceans. They realized they knew less about earth’s oceans than the surface of Mars or the far side of the moon.

An underwater camera must remain tethered to a research vessel for receiving power or sent to a ship periodically to recharge its batteries. This limitation is a big challenge, preventing easy and widespread explorations underwater.

MIT engineers took up the challenge of overcoming the problem. They came up with a camera that does not require batteries, works underwater, and transmits wirelessly. Compared to other underwater cameras, the new camera is more than 1000,000 times more energy-efficient. The device even takes color photos, transmitting them wirelessly through the water.

Sound powers the new autonomous camera—converting the mechanical energy of sound waves into electrical energy for powering its imaging and communications circuitry. After capturing the image, the camera encodes the data and uses underwater waves to transmit it to a receiver for reconstructing the image.

As the camera does not need a rechargeable power source, it can run for a long time before retrieval. This enables scientists to explore remote areas under the ocean. The camera is helpful in capturing images of ocean pollution and monitoring the health and growth of fish.

For a camera that can operate autonomously underwater for long periods, engineers required a mechanism for harvesting underwater energy by itself while using up very little power internally.

The camera uses transducers made of piezoelectric materials that the engineers placed around its exterior. The transducers produce an electrical signal when sound waves hit them. The sound waves may come from any source, such as from marine life or a passing ship. The camera then stores the energy it has harvested, until it has enough for powering its electronics.

The camera has ultra-low-power imaging sensors to keep its power consumption at the lowest possible levels—but these sensors capture only gray-scale images. Moreover, underwater environments are mostly dark, so the camera also needs a low-power flash.

MIT engineers solved both problems simultaneously by using three LEDs of red, blue, and green colors. For capturing an image, the camera first uses the red LED, then repeats the process with a blue LED, and finally with the green LED.

Although each image is black and white, the white part of each photo has the reflection of its respective colored light. Combining the image data during post-processing reconstructs the color image.

The engineers use an underwater backscatter process to transmit the captured image data after encoding it as bits. A nearby receiver transmits sound waves through the water to the camera, reflecting it back just as a mirror would. The camera can choose to either reflect the sound back to the receiver or act as an absorber and not reflect it.

The transmitter has a hydrophone next to it. If it senses a reflected signal from the camera, it treats it as a bit 1. If there is no signal, then it is a bit 0. The receiver uses this binary information for communicating with the camera.

What are Radar Sensors?

Autonomous driving requires the car to have radar sensors as its ears. Originally, the military and avionics developed radar for their applications. Automobiles typically use millimeter wave radar, with a working frequency range of 30-300 GHz, and wavelengths nearer to centimeter waves. These millimeter wave radar offer advantages of photoelectric and microwave guidance to automobiles, because of their significant penetration power.

Automobile collision avoidance mainly uses 24 GHz and 77 GHz radar sensors. In comparison with centimeter wave radar, millimeter-wave radar offers a smaller size, higher spatial resolution, and easier integration. Compared to optical sensors, infrared, and lasers, millimeter wave radar has a significantly stronger ability to penetrate smoke, fog, and dust, along with a good anti-interference ability. Although the millimeter band radar is essential for autonomous driving, heavy rain can significantly reduce the performance of radar sensors, as it produces a large interference. 

Automobiles first used radar sensors in a research project about 40 years ago. Commercial vehicle projects started using radar sensors only in 1998. Initially, they were useful only for adaptive cruise control. Later, radar sensors have developed to provide collision warnings also.

Radar sensors are available in diverse types, and they have a wide range of applications. Automobile applications typically use them as FMCW or frequency-modulated continuous wave radars. FMCW radars measure the air travel time and frequency difference between the transmitted and received signals to provide indirect ranging.

The FMCW radar transmits a frequency-modulated continuous wave. The frequency of this wave changes with time, depending on another triangular wave. After reflection from the object, the echo received by the radar has the same nature of frequency as the emitted wave. However, there is a time difference, and this tiny time difference represents the target distance.

Another radar in common use is the CW Doppler radar sensor. These sensors use the principle of the Doppler effect for measuring the speed of targets at various distances. The radar transmits a microwave signal towards the target, analyzing the frequency change of the reflected signal. The difference between the two frequencies accurately represents the target’s speed relative to the vehicle.

Autonomous vehicles use radar sensors as their basic but critical technical accessories. The radar sensor helps the vehicle to sense objects surrounding it, such as other vehicles, trees, or pedestrians, and determine their relative positions. Then the car can use other sensors to take corresponding measures. Radar sensors provide warnings like front vehicle collisions and the initial adaptive cruise. Vehicles with autopilot radars require more advanced radar sensors such as LIDARs that offer significantly faster response speeds.

Autonomous vehicles must develop technologically. Autonomous driving basically requires an autonomous vehicle to quickly understand and perceive its surrounding environment. This requires the coordination of various sensors, allowing the car to see six directions and hear all. Reliable and decisive driving by an autonomous vehicle requires timely and accurate sensing of roads, other vehicles, pedestrians, and other objects around the vehicle.

Automotive electronics mainly uses radar sensors to avoid forward collisions, sideways collisions, backward collisions, automatic cruises, automatic start and stop, blind spot monitoring, pedestrian detection, and automatic driving of vehicles.