How does Inertial Positioning Solve the Problem of Gyroscope Drift and Magnetic Field Interference?

In order to solve the problems of integral error and magnetic field interference of gyroscope and electronic compass in attitude calculation of navigation system, a fusion algorithm of Kalman filter and complementary filter was proposed. First, the electronic compass and gyroscope are obtained through the Kalman filter to obtain the optimally estimated quaternion. Then, the complementary filtering algorithm is used to compensate for the drift of the gyroscope to obtain the corrected quaternion. Then, the obtained quaternion and Kalman filters are used to obtain the optimally estimated quaternion, and the second optimal estimation of the quaternion is conducted through the Kalman filter. Then output attitude Angle. The results of the proposed algorithm, the complementary filtering algorithm, and the non-filtering algorithm are compared in the experiment. Experiments show that the algorithm can not only effectively solve the divergence of azimuth error, but also effectively solve the magnetic field interference, and achieve high precision azimuth output.

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With the development of miniaturized inertial devices represented by MEMS (Micro-Electromechanical Systems) sensors, the inertial positioning technology based on strapdown inertial navigation principle and MEMS sensors is increasingly paid attention to. Especially in indoor, underground, mine, underwater, battlefield, and other occasions where satellite signals are difficult to receive [1].In view of the above problems, the electronic compass is often used to correct the gyro. In the indoor, underground, mine, underwater, and other processes, the magnetometer is more prone to interference, resulting in greater deviation of orientation. To solve the problems of magnetometer vulnerable to interference and gyro integral drift, there have been numerous fusion algorithms, such as Kalman filter, untracked Kalman filter (UKF), extended Kalman filter (EKF), etc. [2-4]. These filtering methods need to establish accurate state equations and observation equations. There is another filtering algorithm that extends on the basis of complementary filterings, such as classical complementary filtering and complementary filtering algorithm based on gradient descent method [3-6]. However, the accuracy of this filtering algorithm is not high. Face these problems, this paper proposes an inertial positioning algorithm of Kalman filtering and complementary filtering fusion, the algorithm in the design of Kalman filter, the accelerometer and magnetometer fusion of quaternion as observed value, using the gyroscope of a quaternion as a status value, through the data fusion filtering, complete the quaternion optimal estimate for the first time, For the gyro drift problem, the designed complementary filter is used to compensate the gyro drift, and the corrected angular velocity is obtained, and then the continuously updated quaternion after correction is obtained. Then, the optimal estimation quaternion completed at the first time is estimated through the second Kalman filter, and then the high-precision attitude angle is output.

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What are Tilt Switches and Tilt Sensors?

 

Tilt Sensor

A tilt sensor, or tilt switch, is a device used for measuring the tilt of an object in multiple axes with reference to an absolute level plane. They are small and compact instruments which make them a viable option for many applications where orientation or inclination detection is a key factor, such as warning systems on construction or agricultural vehicles.

Tilt sensors work by detecting changes in angle from a pre-set “zero” state. They are set with a maximum and minimum threshold in which the application will work or be safe to operate based on the specific application’s needs. If the tilt or inclination exceeds these threshold values in either direction, a relay will be engaged and the switch closed, thus sending an operation to an external device such as an alarm or warning light to indicate unsafe or non-working conditions.

Key applications include:

• Bank angle warning system for ride-on lawn mowers
• Safety cut-out for cranes with hydraulic levelling
• Tilt warning system for platform and hoist levelling
• Rollover warning system for agricultural vehicles
• Safety cut-out for aerial work platforms

Other Types of Tilt Switches

You may see many tilt switches today labelled as “non-mercury”. This is because tilt switches in the past, and some today, operate by opening and closing the switch using a small piece of mercury to close the circuit. Depending on the angle and direction of tilt, the bead of mercury comes into contact with an electrode on one end which would determine when it is at an angle exceeding the threshold.

Tilt ball switches are now more commonly used as an alternative to mercury ones, using a metallic ball to act as the mechanism which either opens or closes the circuit. Again, this is dependent on the angle and direction of tilt and therefore location of the ball. Ball switches are now much more common that mercury ones due to their safety and non-toxicity, but they have significant drawbacks such as a lack of noise filtering that means they cannot be used in high-vibration applications.

MEMS sensor switches have many benefits over these other types of tilt sensors. They are far more precise and reliable, as well as having an adjustable trip angle threshold. They also have the functionality to filter noise out for more heavy-duty applications.

What is the structure of a Gyro Theodolite?

 

A gyro theodolite consists of a gyroscope, theodolite and a tripod.

(1) Gyroscope
The gyroscope is the core of the system, which is mainly composed of gyro sensitive parts, electromagnetic shielding mechanism, suspension wire and guide wire, azimuth rotation servo drive device, damping device, inertial sensitive part locking device, support leveling device, photoelectric angle sensor, power supply, control and display.

The sensitive part of the gyro is equipped with a gyro motor that rotates at a constant speed. The gyro motor is suspended on the gyro frame by a suspension wire, and the power is provided by the guide wire.

The gyro sensitive part locking device is to ensure the safety of the gyro sensitive part in the transportation state, and the inertial sensitive part is fixed with the frame.

The purpose of the damping device is to attenuate the swing amplitude of the sensitive part of the gyro after the release, so that the swing state meets the north-seeking requirements, and finally overcome the northing moment, so that the sensitive part of the gyro is relatively stable in a fixed position.

The azimuth indentation servo drive system can realize the azimuth rotation of the gyro, provide rotational torque and stable transmission.

The supporting and leveling device can realize the mechanical and optical docking of the theodolite and the gyroscope, the leveling of the entire instrument and the installation and fixation of various components.

The photoelectric angle sensor includes a photoelectric angle sensor that detects the swing angle of the inertial sensing part and a grating code disk system that detects the azimuth rotation angle of the gyro.

Electro-magnetic shielding is mainly used to shield the interference of internal and external magnetic fields on gyro north finding.

The control and display part collects and processes signals through sensors, and completes the functions of locking and releasing the sensitive part of the gyro, damping control, azimuth tracking, communication, calculation, sending and displaying true north position.

(2) Theodolite
Theodolite is the bearing extraction device of the system. It is also possible to measure the geographic azimuth or coordinate azimuth of the target by aiming at the target. The theodolite has a self-collimation function, which is convenient for measurement and calibration. Usually theodolite has a serial communication interface, which can realize the serial data communication and command system with the gyroscope.

(3) Tripod
The tripod provides support for the gyro theodolite.

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How Does A Quartz Flexible Accelerometer Work?

 

Quartz flexible pendulum accelerometer is a force feedback pendulum accelerometer developed on the basis of liquid floating pendulum accelerometer. The main difference between the two is that the detection quality of the quartz flexible accelerometer is not floating, but is elastically connected to the flexible beam support, introducing elastic moment, so it has higher accuracy, strong anti-interference ability, large measurement range, and overload capacity.

The performance of flexible materials directly affects the performance of the accelerometer, and the materials that can be used as a flexible pendulum are mainly metal and quartz. The traditional liquid-floating pendulum accelerometer pendulum adopts metal materials. The thermal expansion coefficient of quartz is much smaller than that of steel, and the material performance is better than metal. In addition, quartz has high fatigue strength and low hysteresis of the material itself, which is very suitable for the pendulum of accelerometer. As soon as the quartz flexible accelerometer came out, it quickly replaced the liquid-floating accelerometer and became an indispensable key component in the inertial navigation and guidance system.

At present, quartz flexible pendulum accelerometers have been widely used in the measurement of various linear acceleration, vibration acceleration, speed, distance, angular velocity, angular displacement and other parameters, and are used in satellite microgravity measurement systems, high-precision inertial navigation systems, and rock-based drilling and oil drilling, continuous inclinometer systems, launch vehicles, ballistic missiles, spacecraft and other military and civilian fields.

What is the structure of a Gyro Theodolite?

 A gyro theodolite consists of a gyroscope, theodolite and a tripod.

(1) Gyroscope
The gyroscope is the core of the system, which is mainly composed of gyro sensitive parts, electromagnetic shielding mechanism, suspension wire and guide wire, azimuth rotation servo drive device, damping device, inertial sensitive part locking device, support leveling device, photoelectric angle sensor, power supply, control and display.

The sensitive part of the gyro is equipped with a gyro motor that rotates at a constant speed. The gyro motor is suspended on the gyro frame by a suspension wire, and the power is provided by the guide wire.

The gyro sensitive part locking device is to ensure the safety of the gyro sensitive part in the transportation state, and the inertial sensitive part is fixed with the frame.

The purpose of the damping device is to attenuate the swing amplitude of the sensitive part of the gyro after the release, so that the swing state meets the north-seeking requirements, and finally overcome the northing moment, so that the sensitive part of the gyro is relatively stable in a fixed position.

The azimuth indentation servo drive system can realize the azimuth rotation of the gyro, provide rotational torque and stable transmission.

The supporting and leveling device can realize the mechanical and optical docking of the theodolite and the gyroscope, the leveling of the entire instrument and the installation and fixation of various components.

The photoelectric angle sensor includes a photoelectric angle sensor that detects the swing angle of the inertial sensing part and a grating code disk system that detects the azimuth rotation angle of the gyro.

Electro-magnetic shielding is mainly used to shield the interference of internal and external magnetic fields on gyro north finding.

The control and display part collects and processes signals through sensors, and completes the functions of locking and releasing the sensitive part of the gyro, damping control, azimuth tracking, communication, calculation, sending and displaying true north position.

(2) Theodolite
Theodolite is the bearing extraction device of the system. It is also possible to measure the geographic azimuth or coordinate azimuth of the target by aiming at the target. The theodolite has a self-collimation function, which is convenient for measurement and calibration. Usually theodolite has a serial communication interface, which can realize the serial data communication and command system with the gyroscope.

(3) Tripod
The tripod provides support for the gyro theodolite.

If interested, pls contact us : info@ericcointernational.com

What Is The Difference Between MWD And LWD?

 At present, the main technology for horizontal well drilling is MWD, and the technology used for formation evaluation is called LWD (logging while drilling or FEMWD-measurement while drilling system for formation evaluation). The measurement while drilling system is composed of downhole sensor components, data transmission, downhole recording device and surface detection and processing equipment. The while drilling system uses sensors near the upper part of the bit to measure drilling parameters and formation parameters. The data measured during drilling is transmitted to the surface in real time. MWD can generally measure well deviation, azimuth and tool face direction.

In addition to the above, LWD can also measure formation parameters such as resistivity, natural gamma, lithological density, neutrons, and acoustic waves. In addition, drilling tool vibration analysis technology can also be used to guide directional drilling. The basis for successful horizontal well drilling is the logging while drilling data and the direction logging while drilling data. The information provided by the LWD tool can evaluate the strata in the borehole. This data determines how to change the direction of the borehole to achieve the desired goal. This method is called “geosteering”.

Geosteering technology includes reliable steering system (MWD), improved new type of geophysical measurement, logging data model, near-bit sensor and measurement transmission motor, and detailed structure drawing with three-dimensional seismic processing.

The following are typical bottom hole combinations and drill string combinations used in geosteering drilling: drill bit + geosteering system (measurement motor, near-bit resistivity, gamma and well deviation, transmitted to the receiving end section) + geosteering tool acceptance end section (Used to receive data from steering system, LWD logging quality, resistivity and Gamma data) + MWD inclinometer (the core of measurement, power inclinometer and data transmission) + non-magnetic drill collar (used to minimize MWD Or install LWD neutron porosimeter) + drill pipe.

What's IMU ? How is the difference between IMU Sensor and Gyroscopes?

IMU sensor stands for inertial measurement unit.IMUs are mostly used in devices that require motion control, such as cars and robots.It is also used in the application of precision displacement calculation with attitude, such as inertial navigation equipment of submarine, aircraft, missile and spacecraft, etc.

 

 

An inertial measurement unit (IMU) is a device that measures the attitude Angle (or angular velocity) and acceleration of an object on three axes.In general, an innovative marketing includes three accelerometer of single shaft and single axis of gyroscope and accelerometer to detect objects in the vehicle coordinate system independent triaxial acceleration signal, and relative to the navigation coordinate system of the angular velocity gyroscope detection carrier signal, measuring angular velocity and acceleration of objects in three-dimensional space, calculated and objects.

 

The difference between IMU and gyroscope

With the continuous development of modern microelectronics technology, the original mechanical gyroscope can now be made very small, small enough to be put into a mobile phone.Mid - and high-end smartphones are now widely equipped with MEMS inertial measurement units (IMUs) for navigation, function control and gaming.

Gyroscope:

Gyroscope is an instrument to measure the angular motion of an object.By measuring the offset of the biaxial base point of the gyroscope in different motion states, the horizontal, vertical, pitch, acceleration, course and azimuth of the object can be calibrated. 

 

IMU
The inertial measurement unit, which contains the gyroscope in the IMU.