Gyroscopic Stabilization

 

Blog Published by Students of VIT, Pune

Dnyaneshwari Patil - C54

Kinjalk Patil - C55

Samiksha Patil - C62

Vaibhav Patil - C66

Vivek Pawar - C71

    A gyroscope is a device used for measuring or maintaining orientation and angular velocity. It is a spinning wheel or disc in which the axis of rotation is free to assume any orientation by itself. 

 

Schematic of Gyroscope

Gyroscopic Stabilization:

           The resistance of a rotating body to a change in its plane of rotation. Gyroscopic stability accounts for the stability of a spinning discus. A spinning body always tends to maintain the orientation of its spin axis in space, for example, a bullet fired from a rifle. The external torque in suitable direction is required to change the orientation of spin axis. Thus the basic property of the gyroscope is ,it opposes the precession of the axis of spin by applying the reactive gyroscopic couple. This property is used in automatic pilot for ships and air craft’s ,in stabilizing rifle bullet, in stabilizing air and sea vehicles ,etc. However, very little or no success is obtained in stabilization of single track land vehicles. In air or sea vehicles such as, aeroplanes and ships, always external disturbing couple is acting on the vehicle. For the stability of such vehicle it is essential to neutralize the effect of external disturbing couple by applying equal and opposite couple. This can be achieved with the help of gyroscope. In such vehicles the axis of gyroscope is made to precess by some external means such that the reactive gyroscopic couple should be as for as possible equal and opposite to the external disturbing couple.

            Spinning flywheels or gyroscopes can stabilize the orientation of objects. This property is exploited in a variety of applications including children’s toys, marine gyro-stabilizers, gyro-compasses, and many more. Apart from being of uttermost practical importance, gyroscopes fascinate physicists for their interesting behavior. The sometimes counter intuitive dynamics of gyroscopes are frequently among the most difficult subjects encountered by new students in physics. This is evidenced by a vast body of literature on illustrating and teaching gyro dynamics. The mathematics of the dynamics of bodies in contact with gyroscopes is far from trivial, and apparently simple phenomena turn out to be very complicated. For example, the stability of a bicycle seems to be related to the conservation of angular momentum of the front wheel, but the mathematical description is rather involved and even the fact itself is not without contradiction. The stabilizing effect of a gyroscope can be nicely demonstrated under conditions of weightlessness such that the position of the centre of mass is conserved, see Fig. When the astronaut kicks the gyroscope slightly, it translates in space, while its axis of rotation is conserved. Similar to the spinning wheel of a bicycle, angular momentum defines an axis whose orientation is stable. However, just as for the bicycle wheel, the object is free to rotate around this axis.

 

1.  Gyroscopic Stabilization of Ships

Gyroscopic Stabilization in Ships

Ships or sea vessels required stabilization when they face heavy sea waves. A disturbing couple acts on the ships due to sea waves, hence stabilization of ships is necessary. Due to sea waves, ships will either roll or pitch. The amplitude of rolling is much higher than the amplitude of pitching. The gyroscope can be used for reducing the amplitude of rolling and hence, stabilizing the ship. The fundamental requirement of the gyroscopic stabilization is that, gyroscope should be made to process by some external means (e.g. electric motor) in such a way that, the reactive gyroscopic couple exerted by the rotor should oppose any distribute couple which may act on the ship.

      The gyro stabilizes the boat through the energy it creates spinning a flywheel at high revolutions per minute. The subsequent angular momentum, or stabilizing power, is determined by the weight, diameter and RPM of the flywheel and measured in Newton meters. The output rating in Newton meters is the amount of power the unit is capable of generating to stabilize the boat. The more output, the more anti-rolling torque generated by the gyro to stabilize the boat.

 

2.    Gyroscopic Stabilization of Two-Wheelers

Self Balancing Scooter by Honda

The gyro stabilizer is designed to improve the stability of two wheelers for better safety. Torque is generated by the rotating front road wheel of a two-wheeler for balance.. A gyro stabilizer for a two-wheeler thus includes a sensor for detecting the angular momentum of the front road wheel. An electric gyro attached to the front fork of the vehicle is driven at a variable speed to generate a compensating angular momentum equal to the difference between the optimal angular momentum and the angular momentum of the road wheel.

When the angular momentum of the road wheel is below the optimum, the gyro is driven the same direction as the road wheel to provide supplemental momentum, so that the sum of their momentum is equal to the optimal angular momentum. When the angular momentum of the road wheel exceeds the optimum, the gyro is driven in the opposite direction as the road wheel to provide a counteracting momentum, so that the sum of their momentum is still equal to the optimal angular momentum. Thus the combination of the road wheel and gyro is always optimized for the best stability and steering response throughout the entire speed range of the motorcycle.

 

3.    Gyroscopic Stabilization of Airplanes

Flying Wing Aircraft

 

        A flying wing aircraft is superior to conventional fixed wing aircraft in terms of aerodynamic and structural efficiency which reduces fuel and weight required, thereby increasing fuel efficiency. Besides the above mentioned reasons, the flying wing configuration garnered special military interest for stealth based operations owing to its low radar reflections and subsequent low observability. Absence of tail and other vertical surfaces reduce the radar cross section of the aircraft which reduces its radar signature. But these advantages come at the cost of stability and control issues. Absence of vertical stabilizer renders the tailless aircraft with low yaw stiffness and damping. Therefore, tailless aircraft are often unstable in directional dynamics besides exhibiting poor lateral-directional response. In addition to the stability issues, absence of vertical deflector causes issues in yaw control. These handicaps have therefore forbidden the use of tailless aircraft in civilian flight domain despite them being the most efficient configuration for flying. Although, they have been used for military applications, the aircraft’s efficiency and control performance can still be improved. So, a very immense work is going on in this field regarding the stabilization of such systems with the help of gyroscopes.

4.    Gyroscopic Stabilization of Long Range Surveillance Cameras

 

Gyro-Stabilized Camera

Some may wonder why gyro stabilization is needed when the cameras they use like a cell phone or a GoPro produce usable images without it. This is because the need for stabilization is proportional to the camera’s field of view. An iPhone for example has a wide field of view (60°) and a GoPro has an extra wide field of view (120°). If the camera is bumped and consequently shakes by two degrees, this means an iPhone’s image shifts by 3% while a GoPro’s image only shifts by 1.5%. These are fairly mild fluctuations to account for, but Infiniti’s long-range zoom cameras often have fields of view that are less than 1°. A camera with a 1° field of view would experience an immense image shift of 200% from that same small vibration.

      With digital stabilization becoming more popular on smartphone cameras, video editing software and even a one-click YouTube option, it’s understandable that many people may think that advanced digital stabilization could then solve any stabilization problems, but for long-range images it’s simply not possible. Digital stabilization works by comparing the frames of the video and watching for sudden shifts in the overall scene. When these shifts occur, the algorithm digitally moves the image back to where it would be if the camera had remained stable. This means the edges of the video now have areas where there is no information. To compensate for this, the final video image is cropped to eliminate those jittery black edges. When the image is shifting by one or two percent, this method can work quite well, but when the image is shifting by over 100%, this is impossible as there is no overlapping image to track.

 

Gyro-Stabilized Camera Used for Surveillance

            Gyro stabilization works by mounting a state-of-the-art FOG (Fiber Optic Gyroscope) or MEMS (micro-electro-mechanical systems) gyroscope to the camera base that measures for any movements that might occur. When the gyroscope senses movement, it then sends a command to the pan/tilt unit to counteract that movement by applying the opposite rotation to the camera. This keeps the image on target, even with massive shifts in movement (up to the rotation limits of the pan/tilt). Performance is then dependent on the accuracy of the gyroscope, the latency in the system, and the speed and precision of the pan/tilt motors. These components can quickly become expensive, which is why we custom configure your camera for the needs of your situation.