Category Archives: Newsworthy

Advantages of Additive Manufacturing

Additive manufacturing, like those from 3-D printers, allows businesses to develop functional prototypes quickly and cost-effectively. They may require these products for testing or for running a limited production line, allowing quick modifications when necessary. This is possible because these printers allow effortless electronic transport of computer models and designs. There are many benefits of additive manufacturing.

Designs most often require modifications and redesign. With additive manufacturing, designers have the freedom to design and innovate. They can test their designs quickly. This is one of the most important aspects of making innovative designs. Designers can follow the creative freedom in the production process without thinking about time and or cost penalties. This offers substantial benefits over the traditional methods of manufacturing and machining. For instance, over 60% of designs undergoing tooling and machining also undergo modifications while in production. This quickly builds up an increase in cost and delays. With additive manufacturing, the movement away from static design gives engineers the ability to try multiple versions or iterations simultaneously while accruing minimal additional costs.

The freedom to design and innovate on the fly without incurring penalties offers designers significant rewards like better quality products, compressed production schedules, more product designs, and more products, all leading to greater revenue generation. Regular traditional methods of manufacturing and production are subtractive processes that remove unwanted material to achieve the final design. On the other hand, additive manufacturing can build the same part by adding only the required material.

One of the greatest benefits of additive manufacturing is streamlining the traditional methods of manufacturing and production. Compressing the traditional methods also means a significant reduction in environmental footprints. Taking into account the mining process for steel and its retooling process during traditional manufacturing, it is obvious that additive manufacturing is a sustainable alternative.

Traditional manufacturing requires tremendous amounts of energy, while additive manufacturing requires only a relatively small amount. Additionally, waste products from traditional manufacturing require subsequent disposal. Additive manufacturing produces very little waste, as the process uses only the needed materials. An additional advantage of additive manufacturing is it can produce lightweight components for vehicles and aircraft, which further mitigates harmful fuel emissions.

For instance, with additive manufacturing, it is possible to build solid parts with semi-hollow honeycomb interiors. Such structures offer an excellent strength-to-weight ratio, which is equivalent to or better than the original solid part. These components can be as much as 60% lighter than the original parts that traditional subtractive manufacturing methods can produce. This can have a tremendous impact on fuel consumption and the costs of the final design.

Using additive manufacturing also reduces the risk involved and increases predictability, resulting in improving the bottom line of a company. As the manufacturer can try new designs and test prototypes quickly, digital additive manufacturing modifies the earlier unpredictable methods of production and turns them into predictable ones.

Most manufacturers use additive manufacturing as a bridge between technologies. They use additive technology to quickly reach a stable design that traditional manufacturing can then take over for meeting higher volumes of production.

New Requirements for Miniature Motors

Innovations in the field of robotics are resulting in the emergence of smarter and smaller robotic designs. Sensor technologies and vision systems use robotic applications in warehousing, medical, process automation, and security fields. Disruptive technologies are creating newer opportunities for solving unique challenges with miniature motors. These include the robotic market for efficient and safe navigation through warehouses, predictable control of surgical tools, and the necessary endurance for completing lengthy security missions.

With industries transitioning to applications requiring collaborative robotics, they need systems that are more compact, dexterous, and mobile. Tasks that earlier required handling by human hands are driving the need for miniaturized motors for mimicking both the capability and size of the hands that accomplished the work.

For instance, multiple jointed solutions representing the torso, elbow, arm, wrist, etc. require small, power-dense motors for reducing the overall weight and size. Such compact solutions not only improve usability but also improves autonomy and safety, resulting in faster reaction times due to lower inertia. Therefore, robotic grippers, exoskeleton, prosthetic arms, and humanoid robots require small, high-power density motors. Power density is the amount of power a motor generates per unit of its volume. A motor that generates greater amounts of power in a small package, has a higher power density. This is an important factor when there is a space constraint, or where a high level of output is necessary when a limited space.

Manufacturers can miniaturize motors with high power densities. Alternately, they can increase the capability of current designs. Both options are critical in reducing the space that motion elements occupy. High efficiency is necessary to obtain the maximum power possible from a given design. Here, BLDC or brushless DC motors and slot-less motor designs in combination with efficient planetary gearboxes can offer powerful solutions in small packages. Brushless solutions are flexible enough for engineering them to meet customer requirements like long and skinny designs, or short, flat, low-profile configurations.

Smooth operation and dynamic response can result in these miniature motors being dexterous and agile. Slot-less BLDC motors achieve this by eliminating detent torque, thereby providing precise dynamic motion with their lower inertia. Applications requiring high dynamics, such as pick-and-place systems and delta robots, must be able to accelerate/decelerate quickly and constantly. Coreless DC motors and stepper motors with disc magnets are suitable for applications requiring critical characteristics like high acceleration as they have very low inertia.

Ironless brushed DC motors with their high efficiency, are the best choice for battery-powered mobile applications to extend their operational life between charges. Several robotic applications now run on battery power, thereby requiring motors with high efficiency for longer running times. Other applications require high torque at low speeds, and it is possible to achieve this by matching the motor with a high-efficiency gearbox.

Some applications that are inhospitable to humans may need robot systems capable of enduring difficult environmental conditions. This may include tremendous vibration and shock. With proper motor construction, it is possible to improve their reliability and durability when operating under such conditions.

Mobile Screen Over Your Eyes

It is no longer necessary to hold a mobile with the hands. How? Thanks to AR or Artificial Reality eyeglasses, it is now possible to transfer the screen of the mobile device to the lens of a pair of eyeglasses. Although this technology was around for a while, the glasses were rather cumbersome and bulky.

Now, Trilite Technologies of Vienna, Australia, has a newer approach to AR glasses that make them look and feel just like normal glasses. According to their CEO, Dr. Peter Weigand, so far, there have been three types of light engine technologies.

The first was the LCoS technology. This is a panel-based technology, and it requires optics with illumination. It is necessary to have a nice, homogeneous, and smooth illumination, and a waveguide must carry the input image. This is not a very efficient technique, and it has a number of optical elements, making it bulky.

The other was the MicroLED display technology. This is semiconductor-based and far superior to a reflective display as it emits its own light. However, it is still a challenge to make the display visible in outdoor applications. And, the two-dimensional display does not scale up when moving to higher FOV or Fields of View and higher resolutions.

The third was the Laser beam scanner technology. This has the highest level of miniaturization. Typically, it has an RGB laser module with three separately mounted lasers as the red, blue, and green light sources. Optics follows the laser module to merge the three beams of lasers into a single ray. A set of MEMS mirrors follows, generating the image scans for the eyeglass display. Two mirrors are necessary, one for the X- and the other for the Y-axis.

According to Weigand, the latest generation of these scanners uses a single MEMS mirror that can move in both x and y-direction. This two-dimensional mirror helps to achieve a lighter and smaller product.

Electronics create the image for display by modulating the lasers. Coupling the image to an optical waveguide allows it to be sent to the display. For this, the laser scanner uses relay optics, a rather large optical element. Coupling the laser beam scanner into the input coupler of the waveguide directly, allows the display engine to be made to a small size. The entire arrangement contains the collimating optics, the MEMS mirrors, and the three lasers.

Trilite Technologies is able to make very small scanners because of its design philosophy. They have designed their scanner such that software rather than hardware handles many of the scanning functions. The other significant contribution to the small size comes from using a single two-axis MEMS mirror rather than one mirror for each axis.

The waveguide contains the optical input coupler as an integral part. This coupler has a pattern of microstructure gratings on its surface, allowing light to enter. The output side, where the light emerges from the waveguide, also has a similar structure. The waveguide conveys the image to the lens and, at the same time, combines the incoming with the generated digital light, allowing the user to see both the digital image and the real-world scene through the eyeglass lens.

Optical Microphone Watches Sound

A research team from Carnegie Mellon University has claimed to have developed an optical microphone or camera system that can monitor sound vibrations very precisely. The precision is so high that the camera can capture separate audio of individual guitars playing simultaneously. That allows the camera to reconstruct the music faithfully and accurately from a single instrument even when it is playing in an orchestra or band.

Even using the most directed and high-powered microphones it is not possible to totally eliminate neighboring sounds, effects of acoustics, and ambient noise when capturing audio. The research team has used a novel approach. They used two cameras along with a laser beam. This allows them to sense the high-speed but low-amplitude vibrations from the surface of the instrument. The team uses these vibrations for reconstructing sound. The unique arrangement allows them to isolate the audio and capture it without a microphone and with no interference.

The team claims to have invented a new way of seeing sound. The camera system is innovative, represents a new device for imaging, and makes it possible to see things that are not visible ordinarily to the naked eye. The team has successfully completed several demonstrations for showcasing the effectiveness of sensing vibrations and reconstructing sound faithfully and with quality.

During their demonstrations, the team was able to successfully capture isolated audio from separate guitars that were playing together, and the audio of individual speakers that were playing assorted music at the same time. For instance, they analyzed vibrations from a tuning fork. They also captured the vibrations on a bag of burritos placed near a speaker thereby capturing the sound from the speaker.

The team significantly improves the work done earlier for capturing sound by computer vision. Where earlier researchers used high-speed cameras for producing a high-quality recording, the present researchers used ordinary cameras costing only a fraction. The dual-camera is necessary for capturing vibrations from moving objects, such as the movements of the instrument when the musician is playing it, while at the same time, sensing individual sounds from many other points.

The team claims they have improved the optical microphone to make it more usable and practical. They claim to have improved the quality while reducing the expenses.

According to the team, the system operates with two types of shutters—a global shutter and a rolling shutter. An algorithm analyzes the difference in speckle patterns between the two streams of video. It converts the differences into vibrations for the reconstruction of the sound.

A speckle pattern is a result that coherent light or laser generates after its reflection off a rough surface. By aiming a laser beam at the vibrating surface, the team created the speckle pattern. This speckle pattern changes with the changes on the surface as it vibrates. The rolling shutter rapidly scans the speckle pattern from top to bottom and produces the image by stacking rows of pixels one on top of the other. At the same time, a global shutter captures the entire speckle pattern in a single instance.

Comparing Polyimide Flex Heaters and Silicone Rubber Heaters

Commercial, industrial, military, and aerospace applications use flexible heaters to deliver particular amounts of heat to specific places. The heaters serve multiple purposes, starting from warming food in cafeterias, drying the condensation on aerospace control panels, to controlling temperatures in medical equipment.

These tiny heaters are unique in the sense they are flexible. It is possible to bend them without compromising their heating operations. As flex heaters are very thin, they can squeeze into inter-component space without dislodging. However, the types of materials that make up these heaters impose certain limitations. These are temperature limitations, and the limitation on how much they can bend. Understanding these limitations is necessary for creating designs suitable for the application.

Flexible heaters are typically made from two types of materials—Polyimide and silicone rubber. The thickness of the materials used defines the amount the heater can safely bend without damage. Polyimide flex heaters with etched foil heating elements can be as thin as 0.0007 inches. This thickness allows Polyimide flex heaters to bend around multiple curves within the application.

In contrast, silicone rubber flexible heaters, with etched foil elements, can only go down to a thickness of 0.03 inches. Those with wire-wound elements can at best be 0.056 inches thin. Therefore, although the heater with etched foil elements can have a bend limitation of 1.5 inches, those with the wire-wound elements can bend still less.

Therefore, applications with curved and bent surfaces prefer using Polyimide flex heaters, and those with flat surfaces can do with either Polyimide or silicone rubber.

The range of temperatures offered by a flexible heater depends on the elements and the types of materials it uses. The application defines the temperature desired from the flex heater, depending on the ability of the system to remove the heat and disperse it away from the heater. The heat transfer is important to prevent the heater from overheating and malfunctioning.

Silicone heaters have an operating range of -70 °F (-56.66 °C) to +400 °F (204.44 °C). This makes them ideal for medium to higher temperature applications. However, they tend to fail if the environment cools below the minimum temperature.

On the other hand, Polyimide flex heaters can operate between -320 °F (-195.55 °C) and +392 °F (+200 °C). This makes Polyimide flex heaters suitable for applications working in very low temperatures, such as in spacecraft and satellites. They can help keep electronics functioning in such low temperatures.

Apart from the outer silicone rubber or the Polyimide covering, there are other structures also that add to the overall thickness. These are the solder tabs, wire connections, and other electronics that must connect to the heater.

Both silicone and Polyimide flex heaters with etched foil elements can have a maximum size of 10 X 70 inches. Their size cannot be larger as the heat produced will not be uniform. On the other hand, wire-wound elements can be as big as 36 X 144 inches. However, the wire-wound elements are strictly for silicone heaters, and suitable for large applications.

MEMS Microphones for Laptops

In the recent pandemic, people took to virtual meetings using their computers and laptops. However, most often, the substandard quality of the audio led to an unsatisfactory experience. That’s because people’s expectation of consumer devices has increased significantly. They want to make high-quality calls from wherever they may be. They could be on the street, in an open office, or in a crowd.

People expect their devices to have ANC or active noise cancellation, transparent hearing, and voice control. However, these require more sophisticated and better microphones.

For instance, people engaged in video conferencing, want their experience to be as close as possible to a real, face-to-face meeting. Now this depends, to a great extent, on the audio quality, and people expect high-quality audio without having to put on additional devices, such as headphones.

Achieving good quality audio requires the application to use a combination of high-quality hardware and software. It is necessary to have algorithms that provide good noise reduction, reverberation reduction, enhanced beamforming, and good direction of arrival detection. These are essential for high-fidelity transmission and audio recording in a wide variety of conditions and situations. However, the quality of the entire chain is dependent on the primary sensor, the microphone.

Most good-quality microphones that have been around for a long time tend to be large and expensive, and primarily confined to audio recording studios. However, consumer equipment typically requires microphones that are mass-produced with tight manufacturing tolerances, and physically small. MEMS microphones suit these requirements very well.

For a microphone to be qualitatively described as good, it must possess some performance characteristics. The first among them is the SNR or signal-to-noise ratio. SNR of a microphone is the difference in its output between a standard reference signal input and the microphone’s self-noise. All elements of a microphone contribute to its self-noise. This includes the MEMS sensor, package, ASIC, and the sound ports.

SNR is important when the microphone is detecting sounds or voices that are at a distance from it. This is because the input signal decreases with distance, as sound level halves at twice the distance. Further, signal losses can come from the system design, room conditions, and sound channel. A good microphone with a large SNR can capture sound even at large distances. This helps with capturing input signals for algorithms, voice commands, and recording.

The next important characteristic of a good microphone is its THD or total harmonic distortion. This refers to the presence of harmonics in the microphone’s output that are not present in the input signal. The point where the THD reaches 10% is important as this represents AOP or acoustic overload point. At this point, the output from the microphone contains clipping and other noises, because the signal is too loud for the microphone.

The latest MEMS technology allows building of studio-level microphones for consumer devices like laptops. This has been aptly demonstrated by Infineon using their XENSIV IM69D127 and IM73A135 MEMS microphones that are allowing OEMs to build laptops with the next level of audio quality.

Reducing Downtime with Remote Alarm Systems

Converting an automated plant to a smart factory is definitely a leap forward. However, it requires enabling a flexible and fully connected system to learn and adapt to new requirements, using a steady stream of data coming from production systems and connected equipment.

Nowadays, there is a convergence of extreme challenges facing manufacturing plants. Most consist of an aging workforce with issues of knowledge transfer, there is increasing demand for high-quality products, the need to use fewer resources, coupled with pandemic situations like that from COVID-19. Not only must these issues be navigated, but manufacturing plants must also maintain ongoing operations while controlling costs. Additional situations like unplanned downtimes can often cause financial disasters and logistical nightmares.

However, there is a silver lining to this dark cloud. IIoT, coupled with machine connectivity and monitoring solutions, is providing solutions for mitigating the above-unexpected problems including challenges of staffing.

A report from Deloitte and the Manufacturing Institute had forecasted an expected shortage of 2 million workers for US manufacturing during 2015-2025. The pandemic has only exacerbated the situation. In their latest report, Deloitte and the Manufacturing Institute claim that by 2030, roughly 2.1 million manufacturing jobs will remain unfulfilled. According to the report, this will cost the US economy about $1 trillion by 2030.

Manufacturing plants spend millions of dollars each year as capital for improving equipment and facilities to protect employees, increase product safety, and reduce costs. This is very important, as equipment may run from 16-20 hours a day, every day, 24/7, especially in food processing plants. Downtime primarily is from equipment failure, causing an astounding $30,000 per hour in these food processing facilities.

This is where the iFIX SCADA system along with the WIN-911 Advanced remote alarm modification software from GE can help ensure the plant continues to operate non-stop.

One of the main ideas is having a sensor monitoring if the machine is working properly, rather than having someone crawl under it to check it out. The other is to use a remote alarm monitoring notification software, allowing fewer people to monitor far more assets with devices they already have—smartphones and tablets. For continuous monitoring of systems, uninterrupted remote availability is essential. The advantage of the system is staff need not remain onsite, and the facility needs fewer people.

Earlier, remote monitoring involved emails, texts, and phone calls. However, monitoring critical plant systems now extend beyond these. They include apps featuring time-saving tools like team chats, real-time alarm acknowledgments for troubleshooting, and resolving plant problems. They also provide detailed reporting so that future incidents do not occur. While this leads to fewer emergency shutdowns, it also requires fewer resources and lower spending on maintenance and overtime.

The mobile alarm notification app is software integrating seamlessly with the HMI or SCADA software of an industrial operation. This allows employees to monitor, receive and acknowledge alarms from machines and plants on smartphones and tablets. This way they can remain free to work from any remote location such as their homes.

Optical Chip is Faster than GPU

Although a typical GPU setup can solve the Ising problem with ease, now a silicon photonics accelerator can also do the same, but at a speed a hundred times faster. The optical computing startup Lightelligence has demonstrated this feat.

The photonic arithmetic computing engine from Lightelligence is an integrated optical computing system, and it is known as Pace. It consists of about twelve thousand photonic devices that run at 1 GHz each. Compared to Comet, the earlier 100-device prototype from Lightelligence that they unveiled in 2019, Pace has a speed advantage of 1 million times. This is the first time that Lightelligence has demonstrated a use case on its hardware that goes beyond AI acceleration.

Lightelligence has designed Pace to run algorithms for problems that belong to the NP-Complete class. These represent one of the most difficult computational issues, requiring much higher speed systems compared to existing accelerators. Pace did not demonstrate optical superiority for all applications. However, it beat a typical GPU when executing the Ising problem by a factor of 100. In fact, it was even defeated by a factor of 25 a system that Toshiba assembled especially for solving the Ising problem—the simulated bifurcation machine running on FPGAs.

With a huge state space, NP-complete problems require very large computing resources for tackling them. The computing time depends on a polynomial of the size of the problem, scaling in proportion. This class includes the Ising problem, traveling salesman problem, and the graph max-cut/min-cut problem. In reality, NP-Complete problems can be found in scheduling, bio-informatics, material discovery, circuit design, power grid optimization, and cryptography applications.

According to their CEO Yichen Shen, Lightelligence decided to demonstrate the acceleration of NP-Complete problems as this best illustrated the advantages of optical computing.

The chief advantage of the optical compute engine from Lightelligence is it can compute matrix multiplications much faster than GPUs can. Typically, GPUs take several hundreds of clock cycles to complete a 64 x 64 matrix multiplication. According to Lightelligence, Pace can do it in about 5 nsec. As NP-Complete problems require several iterative matrix multiplications, Pace has the upper hand. Lightelligence wanted a problem that best demonstrated the superiority of this new technology.

The major factor for Pace is the iterative nature of the algorithms that the NP-Complete problems use. Moreover, the successive matrix multiplications depend on the result of the previous calculations. In GPUs, system electronic parts cause the bottleneck, as data must shuttle to and from the memory in between multiplications. With bigger commercial use cases, the read and write cycles in digital electronics increases tremendously such that the entire computing system slows down. Lightelligence is confident it will be able to demonstrate advantages at least several times faster, if not 100 times.

Optical computing has numerous advantages. Based on silicon photonics, Its main advantage is its speed—several orders of magnitude improvements in power efficiency and computing speed. Basically, the system directs modulated infrared light within silicon wires or waveguides. Scientists accomplished this by using standard CMOS processes.

Improvements in Machine Vision

The way consumers now interact with retailers, banks, and the hospitality industry, has undergone a sea of change. There are many self-service kiosks and ATMs for the consumers to interact, and this is undergoing a revolution. However, these improvements mean the back-end systems must undergo a huge improvement in terms of new hardware, firmware, software, and connectivity.

New businesses are getting the most out of their kiosks, with the role of machine vision creating a seamlessly connected experience for their customers. Initially, they had started with a software platform that helped customers execute their requirements more quickly. However, they realized very soon that machine vision could integrate software and physical-device designs.

Customers typically try to create or replicate a better experience. It is not just about pushing through quicker, building lines, or going through traditional use cases. They want to create a richer and more engaging experience with the minimum number of touches. They relish a more personal experience.

The businesses deploying the kiosks want to offer their customers a more seamless experience. Machine vision is playing a massive part in these applications in making the entire process seamless. For instance, postal services can be quite complex, such as when a customer needs to send a parcel through, and machine vision makes sure they fill out their forms the right way.

Machine vision has improved to the extent of recognizing handwriting. It can automatically detect the destination and verify the address. As the customer fills in the form, machine vision, along with the AI system, cleans and corrects the data as the parcel goes through. This ensures the parcel reaches its destination.

Another example is a kiosk connected to a retail bank. Tokenization distinguishes the customer’s skill level when they use the kiosk. This allows it to bypass any instructional content, taking the customer right to the point. That is what the customer expects—when they have used the kiosk once or twice—-they prefer a seamless experience.

Machine vision and AI applications are very useful during hotel check-ins. Most hotels look for a universal premium experience for their customers when they are using the kiosk service, like check-in, valet, or similar services.

Most cases such as the above require tightly integrated machine vision and AI solutions within their kiosk applications. Customers also expect the high-traffic kiosks to stay clean and safe to use.

For this, businesses are opening their kiosks to various options, such as finger and eye-tracking. These new techniques do not require the customer to physically touch the device. However, most customers did not quite adapt to the touchless techniques, and these did not add to their best experiences.

Therefore, businesses have developed advanced techniques like antimicrobial and heat-mapping touched areas on the kiosk. It uses AI and a combination of touchscreen and pressure sensors. With the presence of physical cameras on the screen, the kiosk allows the creation of a complete digital manifest of areas that others have touched. After a threshold, the kiosk shuts down, until a local attendant physically cleans it. The kiosk maintains a complete manifest of who cleaned it and when.

Human-Machine Interaction in Automobiles

In automobiles, there is a need to realize sensing of force, proximity, ambient light dimming, and gesture control with digital optoelectronics components. Optoelectronics sensor devices enable HMI or Human-Machine Interaction. This requires sensing user inputs and lighting conditions, allowing drivers to keep their eyes on the road. It is possible to connect most optical sensors nowadays to the central controller via the I2C interface.

By setting the internal settings of ASICs or Application Specific Integrated Circuits, it is possible to adjust and fine-tune sensitivity, driving currents, measurement speed, and other parameters to the specifications of the application. This allows force measurement on a given surface for detection or inputs, proximity, and gesture control on the central console, and contrast regulation for adjusting the screen backlight.

Force sensing is necessary to detect an input or control function requiring a force or pressure, adequately strong, to trigger a function. Force sensing in automobiles can also detect false forces, such as from an accidental brush over a touch screen or button. Proper sensing of force allows expanding on input possibilities, like coupling it with menu selections. Low-profile, AEC-Q101-qualified proximity sensors with high sensitivity can have programmable driver current, adjustable in 10 mA steps, flowing through the internal infrared emitter.

Such sensors are popular in force sensing applications. Such applications typically require fine-tuning of sensor performance depending on the given mechanical setup. Implementation of this function requires placing the sensor underneath a surface where the application of force is likely. The high sensitivity of the sensor within a region of 3-10 mm allows the detection of small changes in the displacement of the surface.

Center displays in vehicles use AEC-Q101-qualified proximity sensors. This allows for both gesture and proximity control. Rather than use an internal emitter, the proximity sensor has three current drivers, each with a designated pin. These can directly drive external infrared emitters without needing additional circuitry. This results in a highly flexible solution, where it is possible to choose a specific external infrared emitter to use and their placement with reference to the sensor.

For detecting gestures, it is typical to use narrow-angle emitters. This allows properly defining the area wherein it is necessary to detect motion. For wide areas, it is customary to use wide-angle emitters, such that the sensor solution can cover a wide area. This allows the sensor to cover a wide area, and allows detection of user input, regardless of the direction of the user’s hand entering the sensor’s field of view.

Furthermore, it is possible to have individual ADCs on each channel to allow differentiation of the direction of detection. For instance, this allows detecting user inputs from the passenger side, without distracting the driver.

While proximity sensors gather information about happenings in front of the display, ambient light sensors help with the dimming of the display. The main challenge in such applications is the increasing use of dark cover material used in the interiors of vehicles. At times, these cover materials allow the passing of less than 1% of visible light. Therefore, it is necessary to use a sensor with high sensitivity.