How does a magnetostrictive position transducer measure angular displacement?
1 Answer
A magnetostrictive position transducer, also known as a magnetostrictive sensor or a magnetostrictive encoder, is a type of sensor used to measure linear or angular displacement. In the case of measuring angular displacement, it typically works using the following principles:
Magnetostriction Effect: Magnetostriction is a property of certain materials that causes them to change their shape when subjected to a magnetic field. When an external magnetic field is applied to the magnetostrictive material, it causes a mechanical strain or deformation in the material. This deformation is proportional to the strength of the magnetic field.
Waveguide Wire: The magnetostrictive position transducer consists of a waveguide wire made of a magnetostrictive material, such as nickel or cobalt-based alloys. This wire is usually installed along the path of motion and secured at both ends.
Magnetic Pulse Generation: A special electronic circuit generates a short, high-intensity magnetic pulse along the waveguide wire. This pulse is typically generated by passing an electrical current through a coil wrapped around the waveguide wire.
Propagation of Stress Waves: When the magnetic pulse is applied, a stress wave (also known as a torsional wave or a magnetostrictive wave) is generated in the waveguide wire. The stress wave travels along the wire in both directions from the point of the magnetic pulse.
Interaction with Position Magnet: A position magnet is attached to the moving part whose angular displacement needs to be measured. The position magnet generates a magnetic field around itself.
Interaction of Stress Waves with Position Magnet: As the stress wave encounters the position magnet, the magnetic field of the magnet affects the propagation of the wave. The strength of the magnetic field at the position of the waveguide wire causes a change in the velocity of the wave.
Time-of-Flight Measurement: Sensors positioned at fixed locations along the waveguide wire detect the stress waves as they pass by. The time it takes for the stress waves to travel between the sensors is measured precisely.
Calculating Angular Displacement: By knowing the speed of the stress wave in the waveguide wire and the time it takes for the wave to travel between the sensors, the angular position of the position magnet can be calculated. The relationship between the time-of-flight and the angular displacement is well-defined, allowing accurate measurements.
By repeating this process for multiple positions of the moving part, the magnetostrictive position transducer can continuously monitor and provide precise measurements of the angular displacement of the object to which it is attached. These sensors are commonly used in industrial applications, robotics, and various other fields where accurate position feedback is required.
Magnetostriction Effect: Magnetostriction is a property of certain materials that causes them to change their shape when subjected to a magnetic field. When an external magnetic field is applied to the magnetostrictive material, it causes a mechanical strain or deformation in the material. This deformation is proportional to the strength of the magnetic field.
Waveguide Wire: The magnetostrictive position transducer consists of a waveguide wire made of a magnetostrictive material, such as nickel or cobalt-based alloys. This wire is usually installed along the path of motion and secured at both ends.
Magnetic Pulse Generation: A special electronic circuit generates a short, high-intensity magnetic pulse along the waveguide wire. This pulse is typically generated by passing an electrical current through a coil wrapped around the waveguide wire.
Propagation of Stress Waves: When the magnetic pulse is applied, a stress wave (also known as a torsional wave or a magnetostrictive wave) is generated in the waveguide wire. The stress wave travels along the wire in both directions from the point of the magnetic pulse.
Interaction with Position Magnet: A position magnet is attached to the moving part whose angular displacement needs to be measured. The position magnet generates a magnetic field around itself.
Interaction of Stress Waves with Position Magnet: As the stress wave encounters the position magnet, the magnetic field of the magnet affects the propagation of the wave. The strength of the magnetic field at the position of the waveguide wire causes a change in the velocity of the wave.
Time-of-Flight Measurement: Sensors positioned at fixed locations along the waveguide wire detect the stress waves as they pass by. The time it takes for the stress waves to travel between the sensors is measured precisely.
Calculating Angular Displacement: By knowing the speed of the stress wave in the waveguide wire and the time it takes for the wave to travel between the sensors, the angular position of the position magnet can be calculated. The relationship between the time-of-flight and the angular displacement is well-defined, allowing accurate measurements.
By repeating this process for multiple positions of the moving part, the magnetostrictive position transducer can continuously monitor and provide precise measurements of the angular displacement of the object to which it is attached. These sensors are commonly used in industrial applications, robotics, and various other fields where accurate position feedback is required.