A yaw rate sensor is a gyroscopic device that measures a vehicle’s angular velocity

Angular velocity

In physics, the angular velocity is a vector quantity which specifies the angular speed of an object and the axis about which the object is rotating. The SI unit of angular velocity is radians per second, although it may be measured in other units such as degrees per second, revolutions per...

 around its vertical axis. The output is usually in degrees per second or radians per second. The angle between the vehicle's heading and vehicle actual movement direction is called slip angle

Slip angle

In vehicle dynamics, slip angle or sideslip angle is the angle between a rolling wheel's actual direction of travel and the direction towards which it is pointing...

, which is related to the yaw rate. The measurement is based on the Coriolis effect

Coriolis effect

In physics, the Coriolis effect is a deflection of moving objects when they are viewed in a rotating reference frame. In a reference frame with clockwise rotation, the deflection is to the left of the motion of the object; in one with counter-clockwise rotation, the deflection is to the right...

.

Types

There are basically two types of Yaw rate sensors: Piezoelectric type and micromechanical

Micromechanics

Micromechanics is the analysis of composite or heterogeneous materials on the level of the individual constituents that constitute these materials.- Aims of micromechanics of materials :...

 type.

In the piezoelectric type, the sensor is a "tuning fork

Tuning fork

A tuning fork is an acoustic resonator in the form of a two-pronged fork with the prongs formed from a U-shaped bar of elastic metal . It resonates at a specific constant pitch when set vibrating by striking it against a surface or with an object, and emits a pure musical tone after waiting a...

"-shaped structure with four piezo

Piezo

"Piezo", derived from the Greek piezein, which means to squeeze or press, is a prefix used in:* Piezoelectricity* Piezoresistive effect* Piezometer* Piezo ignition* Piezoelectric sensor* Piezoelectric loudspeakers* Piezo Audio Amplifier...

 elements (two on top and two below). During straight ahead driving, the upper ones produce no voltage as no Coriolis force acts. But in cornering, the rotational movement causes the upper part of the tuning fork to leave the oscillatory plane creating an alternating current

Alternating current

In alternating current the movement of electric charge periodically reverses direction. In direct current , the flow of electric charge is only in one direction....

 voltage

Voltage

Voltage, otherwise known as electrical potential difference or electric tension is the difference in electric potential between two points — or the difference in electric potential energy per unit charge between two points...

 which is proportional to the yaw rate and oscillatory speed. The output signal's sign depends on the direction (left or right).

In the Micromechanical type, the Coriolis acceleration is measured by a micro mechanical capacitive acceleration sensor placed on an oscillating element. This acceleration is proportional to the product of yaw rate and the oscillatory velocity which is maintained electronically at a constant value. DSTC

Applications

Yaw rate sensors are used in aircraft and in the electronic stability control

Electronic stability control

Electronic stability control is a computerized technology that may potentially improve the safety of a vehicle's stability by detecting and minimizing skids. When ESC detects loss of steering control, it automatically applies the brakes to help "steer" the vehicle where the driver intends to go...

 systems of cars.

See also

• Attitude dynamics and control
  Attitude dynamics and control
  Spacecraft flight dynamics is the science of space vehicle performance, stability, and control. It requires analysis of the six degrees of freedom of the vehicle's flight, which are similar to those of aircraft: translation in three dimensional axes; and its orientation about the vehicle's center...
  
  
• Yaw rate
  Yaw rate
  A yaw rotation is a movement around the yaw axis of a vehicle. It is commonly measured in degrees per second or radians per second.In the general case, is a quite different movement from an increment of its heading angle. Nevertheless, in vehicles that move on a plane like a car or a vessel, both...
  
  
• Electronic stability control
  Electronic stability control
  Electronic stability control is a computerized technology that may potentially improve the safety of a vehicle's stability by detecting and minimizing skids. When ESC detects loss of steering control, it automatically applies the brakes to help "steer" the vehicle where the driver intends to go...
  
  
• Ship motions
  Ship motions
  Ship motions are defined by the six degrees of freedom that a ship, boat or any other craft can experience.- Translation :HeaveSwaySurge-Vertical axis:Vertical axis, or yaw axis — an axis drawn from top to bottom, and perpendicular to the other two axes...
  
  
• Aircraft principal axes
  Aircraft principal axes
  An aircraft in flight is free to rotate in three dimensions: pitch, nose up or down about an axis running from wing to wing), yaw, nose left or right about an axis running up and down; and roll, rotation about an axis running from nose to tail. The axes are alternatively designated as lateral,...