What is an RVDT Rotary Position Sensor？
Jul 27, 2024
RVDT is an abbreviation for Rotary Variable Differential Transformer, which is an angular displacement sensor. It adopts the same differential transformer principle as LVDT, i.e. the rotation of mechanical parts is transferred to the shaft of the angular displacement transducer, which drives the spoiler/core connected to it, changes the induced voltage/inductance in the coil, and outputs voltage/current signals proportional to the angle of rotation.
RVDT non-contact design, with infinite resolution, long service life, high precision, can realize 360 ° rotation measurement, widely used in ball valve position, hydraulic pumps, forklifts, robots, fans and other equipment transmission and feedback control.
RVDT angular displacement transducers are also reliable aeronautical measurement products for applications such as flight control systems (flight controllers), rudders, unmanned helicopters, flap control, and more.
The core features include:
Principles of operation: Through the change of electromagnetic coupling between the rotor and stator windings, the mechanical angle is converted into an electrical signal output.
Benefits:
- No physical contact → Unlimited lifespan (compared to potentiometer wear)
- Withstands extreme temperatures/vibration (Operating temperature: -55°C to 150°C)
- Accuracy ±0.1°, linearity ±0.25% FSO
Typical applications:
- Aircraft aileron/Rudder angle feedback
- Missile guidance system servo control
- Nuclear power valve opening monitoring
Difference with LVDT:
- LVDTs are used for linear displacement measurement; RVDTs are used for rotational displacement measurement.
Similarity: both use principle of electromagnetic induction, frictionless design.
Comparison Table of RVDT vs Optical Encoder vs Potentiometer
| Features | RVDT | Optical Encoder | Potentiometer |
|---|---|---|---|
| Principles of operation | Electromagnetic induction (non-contact) | Gratings/optical signals (non-contact) | Resistive sliding contact (physical contact) |
| Measurement Range | ±40° (standard) | 0~360° (single-turn) or multi-turn | 0~300° (limited mechanical stroke) |
| Accuracy | ±0.1°~±0.5° | ±0.01° (high resolution) | ±1°~±5° (susceptible to wear degradation) |
| Lifespan | Nearly infinite (frictionless) | Long (dependent on bearings/coder) | Short (brush wear, approx. 500,000 cycles) |
| Environmental Tolerance | Excellent (Operating temperature: -55°C to 150°C, vibration-resistant) | Fair (dust/humidity affects optics) | Poor (fear of dust/corrosion) |
| Anti-electromagnetic Interference (EMI) | Strong | Medium | Poor |
| Typical applications | Aircraft control surfaces, missile guidance, nuclear power valves | CNC machines, robot joints | Industrial knobs, low-cost control panels |
| Price | High | Medium | Low |
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