In addition, the increasingly fierce competition has forced the industry to be the first to launch products before the market has yet to shape. This article focuses on how many innovations in RF and microwave technology remove regulatory barriers and assist drone manufacturers in highlighting The difference in the solution, in order to attack the market opportunities.
With the advent of industrial robots, automatic driving, new propulsion technology, and power-saving systems, the transition to UAVs has evolved into a natural progression. Unmanned aerial vehicles have been set to perform a variety of hazards, time-consuming, or difficult to implement Our work, this wave of great leap forward, is leading us towards a more automated and higher-productivity world. The concept of UAV/UAS is not new. Similar patterns have appeared as early as during the heavy use of manned aircraft. the use of.
However, due to limitations in material science, advancement, power and battery, sensors, and software technology capabilities, the applicability of drones to specific industries and uses is limited. In the past, only the military had sufficient financial resources to develop and The use of drones in the environment where personnel are dispatched to the site must bear a high degree of risk. It can replace the task of officers and soldiers in the pursuit of intelligence. Even today, many people still use drones and often listen to news. The military mission arrived at.
On the other hand, low-cost drones with no bare equipment (Bare Bone) quickly set off a boom in casual gamers and enthusiast circles. Drones have not been widely used in commercial applications in the past, but with the industry in parts technology and Computing software has made great progress, and this situation is gradually being reversed.
The commercial drone market is optimistic
The size of the drone market is expected to grow to 21 billion U.S. dollars in 2020. The main force of the current market territory (about 82%) is focused on military applications. Commercial UAV market revenue is expected to reach 25 by 2021. Billion US dollars, annual growth rate will reach 19%.
Commercial and industrial drone markets have a wide range of use scenarios. Drones are pioneering applications such as precision agriculture (spraying pesticides), geomorphology and environmental monitoring, infrastructure monitoring (bridges and reservoirs), public safety surveillance, Commercial freight, border control, oil and gas pipeline monitoring, and many other uses. Each month, dozens of newcomers launch products and services, using drone technology to solve business problems. Simply put, commercial UAV applications There is almost no boundary in the foreground.
Although the drone market heat continues to heat up, many manufacturers have begun to expand their various uses, such as Amazon and Google, which is owned by Alphabet Holdings. The industry is facing many challenges that limit growth.
Regulations/Talents become obstacles to the development of drones
The United States Federal Aviation Administration (FAA) has severely restricted the use of UAVs in public airspace. According to regulations in 2015, UAVs weighing less than 55 pounds are limited to flying within sight of the operator during the day. In other words, the authorities prohibited such drones from flying completely autonomously without personnel monitoring. The FAA established these rules in order to prevent accidents and maintain public safety. From the government’s standpoint, these drones are not equipped with reliable Precise sensors, resulting in too high a risk of derivation, should not be allowed to fly in open public areas. However, authorities still have some open airspace (for example, in open, open farmland), but in most cases, given the limited number of sensors Technology and reliability of sensors that have not been actually verified, FAA took a more conservative position in order to prevent accidents and maintain public safety.
In addition to the obstacles caused by laws and regulations, the competition in the UAV market has become increasingly fierce, creating pricing pressure on manufacturers. Due to the growth potential and business opportunities of drones, there are currently more than 400 companies investing in research and development of drones worldwide. At the same time, the focus of most vendors is to highlight the differences in their hardware rather than to emphasize the added value created by their own drones.
For commercial and consumer drones to be widely used, these flying tools must be equipped with navigation sensors to help them navigate safely and reliably. Like the automotive and industrial equipment market, many of these wireless sensors use RF and microwave technologies. However, most of the companies that use UAVs today are start-up companies. The number of talented people who specialize in RF and microwave design is limited. Even the long-established OEM OEM factories have some RF expertise. However, it is often forced to quickly evaluate, design, and manufacture radar sensor solutions to cater to the rapidly changing UAV market.
Lack of radio frequency talent and commercially available radar solutions have created a vicious circle for the industry. The drone market does not have the ability to provide reliable sensors to support full autonomous flight, which in turn has led to the inability of government authorities to relax the current restrictions on autonomous drones. The ordinance.
Sensing technology protects drone safety
Analog Devices believes that drone manufacturers have the opportunity to influence the drone flight authorities by using radio frequency, microwave, and millimeter-wave technologies and deploying mature sensors on drones to maintain the safety of flying. One example is the use of drones. The deployment of 24GHz radar is one of the most basic and versatile solutions, demonstrating the ability to navigate safely in many contexts because it is a globally accepted industrial/scientific/medical (ISM) utility band.
The 24GHz ISM band radar can be used anywhere in the world without having to obtain a license. It can be used to operate equipment such as car collision avoidance systems and radio altimeters. The radar band can also be used to detect and track multiple different objects, as well as to measure Human-robot flying altitude, and these two are the most basic functions of safe drone flight.
Also note that a common misconception is that the 77GHz radar can be used with the 24GHz ISM radar. According to the current regulations, the 77GHz band is automotive-specific and does not include UAV/UAS. From a technical perspective, the 77GHz radar does provide higher The bandwidth helps improve the resolution, but according to current regulations, it cannot be used on UAVs.
By providing solutions that can operate autonomously on a technical level, manufacturers can take the initiative to influence existing regulations rather than passively wait for the authorities to specify how the industry should operate.
To this end drone manufacturers must take three steps:
1. Establish basic understanding of radar and its various modes.
2. Understand the elements of the RF signal chain that make up a complete radar solution.
3. Use appropriate radar solutions that provide complete hardware configuration and software algorithms that enable them to bring products to market faster.
These steps are described below, as well as constructing one of the possible solutions to assist UAV manufacturers in developing applications such as collision avoidance and radio altimeters using 24GHz radar.
Establish basic understanding of radar and its various modes
The automotive and industrial equipment market often uses radar sensors to detect, measure and track objects, such as blind spot detection and advanced driver assistance systems (ADAS). Compared to optical/visual or ultrasonic sensors, radar sensors can accurately detect And measuring objects, even in harsh environments such as dust, smoke, snow, fog, or poor light, can also detect extreme distances and wide angles.
Typical RF/microwave radars can operate in a variety of modes to match the desired mode of detection and tracking.
. FMCW radar mode measurement of multiple objects
In the FMCW mode, the radar DVD-R/RW is the distance from the stationary object. By adjusting the frequency wave, also known as the FMCW ramp or chirp, the radar can measure To reflect the response of the wave, and then calculate the distance of the target object, speed, and resolution of the angle
Figure 1 shows the FMCW slant wave or chirp generation mechanism during radar transmission and the entire set of important radar equations used to define the radar sensor design information:
Fig. 1 FMCW radar concept
·Distance resolution:
Depends on the transmitter carrier sweep bandwidth (Sweep Bandwidth); the higher the transmitter sweep bandwidth, the higher the radar sensor's ranging speed.
Speed resolution:
It depends on the Dwell Time and the carrier frequency; the higher the carrier frequency or the longer the illumination time, the higher the speed resolution.
·Angle resolution:
Depends on the carrier frequency; the higher the carrier frequency, the higher the angular resolution.
Compared to laser detection or camera detection methods that measure a single location point, only a 2D image is captured from the camera's field of vision. FMCW lasers not only measure continuously, but also measure the target. The reflection information takes the average of multiple data, and then integrates information such as velocity, angle, and distance of the measured object, and draws a 3D view. The distance ranges from several centimeters to hundreds of meters. It can measure single objects and multiple objects.
Distance - Doppler mode analysis distance/speed
In Distance-Dupuy mode, the distance and speed of the object can be analyzed. Distance-Doppler mode is one of the most powerful modes of operation because it can measure two-dimensional Fourier transforms, thereby simultaneously processing Multiple Transmit Ramps or Radon frequencies. The distance after processing - Doppler data is displayed on a map to distinguish objects of different velocities, even if they are distanced from the sensor. The same can be distinguished. This is useful for distinguishing objects that are in different orientations and moving at high speed; for example, when many vehicles are traveling in the opposite direction, or when they are passing, they can use this method to solve the problem. Calculate the complex traffic situation.
Digital beamforming mode display target angle
In the digital beamforming (DBF) mode, the distance and angle of the target can be displayed. The signals received from the four channels are used to estimate the azimuth angle of the target. The displayed message reflects the target in the xy coordinate plane. Spatial distribution. In the DBF mode, the system setting is similar to the FMCW mode, but the intermediate frequency (IF) down-converted signal is treated differently. After the distance is calculated, the target is solved according to the four received channel information. Azimuth angle.
In the DBF mode, the radar's front-end system must be calibrated to eliminate qualitative phase shifts between the received channels. The Analog Radar display (Demorad) system contains factory calibration data that is loaded when the GUI GUI is running. Then, the system will correct the sampled IF signal, and then evaluate the data measured by the sensor.
Because of its high accuracy, low power consumption, and micro-size features, the 24GHz radar is widely used in commercial and industrial applications. These features also make the 24GHz radar suitable for assisting most commercial and consumer drone manufacturers. It can reduce the need for payload and electricity. Figure 2 shows a complete multi-channel radar signal chain. Table 1 shows the radar solutions from Analog Devices to the antenna, enabling engineers to rapidly develop applications.
Figure 2 Analog Devices' 24 GHz Multi-Channel Radar Solution
24GHz radar advantage
When developing radar sensors, a one-dB improvement in receiver sensitivity affects the detection distance. The majority of solutions on the market focus on reducing costs, so the phase noise performance must be sacrificed, and the number of channels must be reduced. .
As a result, the overall receiver signal-to-noise ratio (SNR) will decline, limiting the ability of the radar to detect smaller objects or targets, so that no small objects next to large objects can be detected. In practical applications, radar applications, Frequently busy or congested situations can cause system phase noise to accumulate, causing the radar receiver's sensitivity to degrade. Higher system noise can obscure or hide smaller objects, causing radar to detect objects, which in turn leads to sensors. Security issues. For example, when detecting fine branches, they may be obscured by buildings and cannot be detected. Most single-channel, single-chip, low-cost solutions cannot provide the required performance to perform such identification.
Utilizing the 24GHz multi-channel platform, UAV manufacturers will be able to:
1. Use FMCW radar to detect distances and speeds from objects. The maximum detection distance is up to 200 meters and the resolution is up to 60cm (if the antenna design of the specific application is adopted, the resolution can even be improved to 15cm. ).
2. The horizontal viewing angle is about 120 degrees, and the vertical viewing angle is 15 degrees. The actual visual field range depends on the antenna array design. Combining the antennas with multiple digital beams, the radar can use DBF to calculate the angle information so as to spell a wider field of vision.
3. Compared to traditional low-cost, single-channel radar solutions achieve at least 2 times the sensitivity, up to 1.5 times the detection distance and reduce power consumption.
Demorad system helps development efficiency
The 24GHz radar Demorad system is a novel radar evaluation platform solution with out-of-the-box software examples that allow users to start designing radar sensors in just minutes. In addition, Demorad allows users to quickly build products. Prototype, evaluating various factors of radar R&D, and developing ideal radar sensor products, energy measurement of various real-time information such as the presence/absence of a target/object, movement, azimuth, velocity, and distance from the sensor.
The system hardware solution consists of a radio frequency antenna, a complete RF-to-baseband signal chain and a DSP. The user can quickly connect to the laptop/PC using only GUI software and radar algorithm software.
Users can use this kit to connect to a computer in just a few minutes and load software to construct a fast Fourier transform (FFT) including 2D/3D radar, fixed false alarm rate (CFAR), and classification algorithms to make a complete radar. Prototypes, and the accelerated launch of new drones equipped with functional radars.
Figure 3 shows different perspectives of the 24 GHz Demorad kit with built-in dual-channel transmitter and 4-channel receiver antenna.
Figure 3 Demorad 24GHz Radar Platform Solution
Demorad comes with a complete library of GUI and DSP radar support functions. The Radar signal chain within Demorad contains many basic software algorithms that allow designers to develop R&D work without having to write program code. Use these built-in software algorithms to make Engineers can quickly use radar from the host PC to detect and distinguish targets.
In addition, developers can also edit existing software program code to detect and distinguish various objects in their applications. Demorad provides manufacturers with a higher level of design flexibility, whether or not they have experience in RF design. Can quickly develop applications to facilitate safe drone flight.
The UAV/UAS market has not only grown rapidly, but has also brought endless potential for many new commercial applications. However, to realize this vision, drone manufacturers must lead the industry, use RF, microwave, and millimeter wave sensors to prove their own Drones can fly autonomously and safely. In addition, sensor technology is rapidly evolving. New technologies including LiDAR, ToF, and ultrasound are also emerging.
Drone manufacturers should continue to pay attention to these novel solutions in order to select the latest technologies for their drones. When evaluating these technologies, critical evaluation standards should incorporate radar performance and diversified functions, not just hardware the cost of.