In the previous article, we learned about the origin, principle and types of gyroscopes. So, how does it relate to our daily lives?
Originally used for maritime navigation, gyroscopes have found widespread application in aviation and aerospace with the development of science and technology. Beyond their function as indicating instruments, gyroscopes can also serve as sensitive components in automatic control systems, acting as signal sensors .
As needed, gyroscopes can provide accurate signals such as azimuth, level, position, speed, and acceleration, so that pilots or autopilots can control aircraft, ships, or space shuttles to fly along a certain route. In the guidance of missiles, satellite launch vehicles, or space exploration rockets, these signals are directly used to complete the attitude control and orbit control of the vehicle.
As stabilizers, gyroscopes enable trains to travel on single rails, reduce ship swaying in rough seas, and stabilize cameras mounted on aircraft or satellites relative to the ground. As precision testing instruments, gyroscopes provide accurate positioning references for ground facilities, mine tunnels, underground railways, oil drilling sites, and missile silos.
Gyroscopes have a wide range of applications and play an important role in modern national defense and economic development.
Applications of gyroscopes in aviation
Due to the high-tech development of various electronic devices and computer controls, most modern aircraft designs are statically unstable and must utilize electronic devices and computers to assist in control in order to achieve good flight control.
Controlling this type of aircraft solely with the pilot's fingers would be much more difficult. While the aircraft could still fly, it would experience varying degrees of swaying and would always be in an unstable flight state. Sometimes, even slight deviations in the center of gravity setting could cause instability.
Turbulence in the air can make an aircraft less stable. In such cases, gyroscopes are used to stabilize the aircraft, allowing it to fly smoothly and making it easier for the pilot to control the aircraft and perform various maneuvers more accurately.
The gyroscope's effects are most noticeable to pilots during landing, and it's also the part of landing where the aircraft needs the most assistance. Because landing aircraft are moving slowly and nearing the stall point, they are more susceptible to wind, causing the wings to sway up and down. Pilots must constantly use their fingers to adjust the aircraft's attitude to keep it level and gradually descend. Many novice pilots sometimes make excessive corrections, causing the aircraft to sway even more, easily leading to a stall and a failed landing.
However, if the gyroscope is set to stabilized mode, because the gyroscope's sensors are extremely sensitive, even a slight dip in the wing will trigger the gyroscope to immediately instruct the ailerons to level off the aircraft. This process happens so quickly that you might not even see the wing dip being corrected by the gyroscope. Therefore, you will see the aircraft consistently maintaining a very smooth level while gradually descending, which is very helpful for the pilot.
For fighter pilots, the gyroscope's lock-on function greatly enhances the flying experience. For example, when a fighter jet is flying inverted at extremely low altitude, if the aircraft's performance is good or the adjustments are made correctly, it can usually maintain upright flight even without moving the elevator. However, when flying inverted, it usually requires a slight push on the elevator to maintain inverted flight. Unless one has extremely high skill, it is difficult to keep the elevator push constant with one's fingers to keep the aircraft flying inverted in a straight line.
This is why most people dare to do ultra-low-altitude forward flight but not ultra-low-altitude inverted flybys, or they dare to fly very low in forward flight but usually not inverted flight. When flying forward, the fingers don't need to move the elevator to maintain a straight flight, but when flying inverted, the fingers have to constantly push the control surfaces. With the aircraft's high speed and low altitude, even a slight movement of the finger could result in a crash. Using the gyroscope's locked state makes this very easy.
Because in inverted flight, the gyroscope automatically locks onto the inverted attitude. Even if the elevator stick is centered and not moved, the gyroscope will automatically keep the aircraft in a straight inverted flight, so you don't need to worry about the accuracy of the rudder input. Therefore, you can confidently control the aircraft at the far end of the runway to enter an ultra-low-altitude inverted flyby state, and then you don't need to make much control; the aircraft will maintain ultra-low-altitude inverted flyby indefinitely.
Application of gyroscopes in vehicle navigation devices
In-vehicle navigation works by receiving GPS satellite signals, successfully locating the target, determining the route based on the navigation software's built-in database, and then navigating. Because GPS requires the in-vehicle navigation system to be within the direct line of sight of geostationary satellites to function, tunnels, bridges, or tall buildings will obstruct this line of sight, rendering the navigation system inoperable.
Furthermore, navigation systems use trigonometric and geometric principles to calculate a car's position, so the car must be within the line of sight of at least three geostationary satellites simultaneously to determine its location. The more geostationary satellites within the direct line of sight of the navigation system, the more accurate the positioning.
Of course, most geostationary satellites are located over densely populated metropolitan areas, so when you are far from urban areas, the navigation system will not be very effective or may not work at all. This is known as the "navigation blind spot".
To address this problem, some navigation manufacturers have found a solution, and the secret to achieving accurate navigation lies in a small device—the gyroscope.
When gyroscopes are applied to in-vehicle navigation systems, they significantly improve navigation accuracy. Their benefits include:
1. The gyroscope can continue to function as a navigation device and correct GPS positioning inaccuracies even when the GPS signal is weak.
When GPS signals are weak, the gyroscope can continue precise navigation based on the known location, direction, and speed, which is the basic principle of inertial navigation technology. It can also correct for excessive positioning errors when GPS signals are weak.
2. Gyroscopes can provide more sensitive and accurate direction and speed readings than GPS.
GPS cannot detect changes in a vehicle's speed and direction in real time; it can only detect them after a certain distance has been traveled. Therefore, when your car changes direction without navigation, a situation like Xiao Chen's occurs: the navigation system cannot recognize the change in direction and consequently provides incorrect guidance. A gyroscope, on the other hand, can detect changes in direction and speed instantly, allowing the navigation software to promptly correct the route.
3. Gyroscopes provide more sensitive and accurate identification when going over overpasses.
While civilian GPS devices lack the precision to detect whether a vehicle has entered or exited an overpass, gyroscopes can detect whether a car has moved upwards, allowing navigation software to adjust its route accordingly. By combining GPS satellite signal navigation with gyroscope inertial navigation, navigation accuracy is significantly improved. Even after losing GPS signal, the system can continue navigation through autonomous calculations, providing drivers with accurate driving directions.
Application of gyroscopes in UAV flight control systems
The flight control system is one of the most important components of a drone, and attitude stabilization control is an effective method for the drone to successfully perform various tasks. In current drone manufacturing and applications, some drone products use a three-axis gyroscope and tilt sensor to form a full attitude stabilization control system.
UAV attitude stabilization control is an internal loop control system, which includes modes such as attitude maintenance and control, and speed control. Internal loop control, based on the flight attitude acquired by the three-axis gyroscope and tilt sensor, achieves flight attitude stabilization and control by controlling the elevator and rudder.
The three-axis gyroscope is mainly used to measure the angular velocities of pitch, roll, and yaw angles during UAV flight, and calculates the angle changes based on the integral of the angular velocity. A dual-axis tilt sensor is typically used, forming a full-attitude stabilization control loop with the three-axis gyroscope.
The angular velocity information measured by the gyroscope is used for stability augmentation feedback control, making the aircraft more "sluggish" to maneuver. The roll and pitch angles are then measured using a tilt sensor. The angular velocity information from the gyroscope and the attitude angles from the tilt sensor are then strapped together to obtain the fused attitude information. This relatively complex strapdown algorithm can significantly improve attitude accuracy.
Applications of gyroscopes in photography/videography
When we shoot videos or take photos, have you ever considered using a device to keep your "camera" fixed in the same position, maintaining relative stability no matter how your hand is tilted or your body shakes? We all know that only when a phone or camera is relatively "stable" can we capture beautiful images or videos. The core secret to keeping a "stabilizer" stable is the "accelerometer and gyroscope" sensor.
Why are accelerometer and gyroscope sensors considered the core secret of selfie stabilizers? Because the core of a stabilizer is the detection of the camera's posture, followed by real-time control of the motors connected to the camera based on these posture changes. As long as the motors are controlled quickly enough, the camera remains stable in a fixed position. No matter how much your hand moves left or right, or up or down, the stabilizer will keep your camera perfectly still, resulting in stable photos and videos.
The general framework of the stabilizer is shown in the figure below, where the orange part is the working part of the accelerometer and gyroscope sensor.
It feeds back the posture of the "camera device" to the central MCU processing unit. The central MCU unit controls the motor to perform corresponding actions based on the detected posture and movement of the "camera device". The motor's actions keep the "camera device" in a stable and unmoving state, so that the photos taken are clearer and the videos recorded are more stable.
Applications of gyroscopes in smartphones
The closest application of gyroscopes to our lives is in our mobile phones. The main applications of gyroscopes in mobile phones are as follows:
1. Navigation.
Since its invention, the gyroscope has been used for navigation. The Germans first applied it to the V1 and V2 rockets. Therefore, if combined with GPS, the navigation capabilities of mobile phones will reach an unprecedented level.
In fact, many professional handheld GPS devices are also equipped with gyroscopes. If the corresponding software is installed on the mobile phone, the navigation capability is no less than that of many navigation devices used on ships and airplanes.
It can also achieve GPS inertial navigation: when a car is driving in a tunnel or near tall buildings in the city and there is no GPS signal, the gyroscope can be used to measure the car's yaw or linear displacement, so as to continue navigation.
2. It can be used in conjunction with the phone's camera, such as for image stabilization, to maintain image stability during shooting and prevent hand shake from affecting photo quality. When the shutter button is pressed, the phone records the hand's shaking motion and feeds this feedback to the image processor, allowing the phone to capture a clearer and more stable image.
3. Sensors in various games, such as flight games, sports games, and even some first-person shooters, use gyroscopes to fully monitor the player's hand movements, thereby achieving various game operation effects. Those who have used the Nintendo Wii will likely have a deep understanding of this.
4. It can be used as an input device. The gyroscope is essentially a 3D mouse. This function is very similar to the gaming sensor mentioned in the third major application, and can even be considered the same type. By tilting or turning the phone slightly, menus and directories can be selected and operations executed. (For example, tilting the phone forward or backward allows scrolling through contact entries; tilting the phone left or right allows moving pages horizontally or zooming in and out.)
5. This is also the most promising and widely applicable use in the future: enabling mobile phones to perform many augmented reality functions. Augmented reality is a relatively new concept, and like virtual reality, it's an application of computers. Essentially, it allows people to gain a deeper understanding of objects in the real world through the processing power of mobile phones or computers.
If you don't understand, let me give you an example. If there's a building in front of you, point your phone camera at it, and you can immediately see the building's parameters on the screen, such as its height, width, and altitude. If it's connected to a database, you can even see the building's owner, construction date, current use, and capacity.
A Brief Introduction to the Latest Gyroscope Technologies and Development Trends
Currently, gyroscope technology is shifting from traditional mechanical rotor gyroscopes to new types of gyroscopes represented by optical gyroscopes. Below is a brief introduction to several new gyroscope technologies at the forefront of the field, hoping to help readers broaden their horizons and understand the latest developments in gyroscope technology abroad.
Helium-neon ring laser gyroscope
Compared to traditional mechanical rotor gyroscopes, its main advantages are no mechanical rotor, simple structure (less than 20 parts), good vibration resistance, fast start-up, high reliability, and digital output.
In addition, some researchers have proposed replacing helium-neon gas with a solid gain medium, which could make the gyroscope have a longer working life, lower cost and simpler to manufacture. This type of gyroscope is also known as a solid-state ring laser gyroscope (solid-state RLG).
Currently, inertial navigation systems based on helium-neon ring laser gyroscopes have been widely used in aviation and maritime navigation, as well as in the navigation, guidance, and control of strategic missiles, becoming one of the main high-performance gyroscopes.
Fiber optic gyroscope
Beginning in the 1960s, the U.S. Office of Naval Research sought to develop a fiber optic angular velocity sensor that was cheaper, simpler to manufacture, and more accurate than a helium-neon ring laser gyroscope, commonly known as a fiber optic gyroscope.
Currently, the most common fiber optic gyroscope is the phase-sensitive fiber optic gyroscope, which measures the phase shift of two counter-propagating beams in a fiber optic coil to sense the rotation of a carrier and thus calculate its angular rate.
Therefore, the accuracy of a fiber optic gyroscope mainly depends on the type of fiber optic cable and the photoelectric detection system used, with the bias typically ranging from 0.001 degrees/hour to 0.0002 degrees/hour. Currently, fiber optic gyroscopes are widely used in torpedoes, tactical missiles, submarines, and spacecraft.
Integrated optical gyroscope
With the development of integrated optical circuits, very complex functions can be realized on a single chip. Integrated ring cavity lasers and photoelectric detection circuits with a diameter of a few millimeters can be integrated on the same chip as the sensing element of an integrated optical gyroscope. This can greatly reduce the mass and size of existing optical gyroscopes, reduce costs and power consumption, better control thermal effects, and increase reliability. Therefore, optical gyroscopes manufactured using integrated optical technology have good development prospects.
Currently, extensive research has been conducted on integrated ring cavity lasers, but key technologies still need to be mastered.
In addition, cutting-edge technologies, including nuclear magnetic resonance and superfluidity, have been validated and will be applied to new gyroscopes in the future.
