Position sensor key term – Ottonix

Incremental sensors

Only bearing change information is provided so that the practice bearing is unknown at startup. Each time the index is made/marks the zero or zero bit of the signaling community. Detected in the homing procedure. Regarding the commutation of brushless motors, motors generally have three magnetic Hall sensors that provide rough positive orientation information for the initial alignment of the magnetic field. Incremental sensors are generally small in size, high in accuracy, and cost-effective.

Affirmative sensors

Provides hands-on physical orientation within one revolution or on a linear travel scale. The motor does not require Hall, and only when the scale of movement exceeds one revolution, it needs to be homing for the rotary application. Sensors are generally larger and more expensive than incremental devices.

Position sensor key term – Ottonix

Multi-turn

Rotating equipment, sensors provide multi-turn practical orientation. It is possible to completely eliminate homing. Multi-reverse devices with internal gearing devices are the bulkiest and most expensive solution.

resolution

The boundary is the smallest azimuth increment that can be moved or measured, which is generally expressed as "count". High-performance servos require high resolution. The positioning system "jitters" between the two counts, so the higher the resolution, the less jitter. Resolution also has a significant impact on speed fluctuations at low speeds. Since velocity is derived from the azimuth reaction, the data in the sample may not be sufficient to accurately derive velocity if the resolution is low. At high speeds, high-resolution devices are capable of generating data rates that exceed the ability of controllers or servo drives to track.

interpolation

As you can see, many sensors generate both sine and cosine signals. The period of these signals is determined by the "pitch" inherent to the device. Using sin/cos information, it is theoretically possible to calculate the signal ratio to achieve infinite resolution. This skill is called interpolation. In practice, the fidelity and signal-to-noise ratio of the sin/cos signal limit the achievable resolution.

accuracy

The boundary says that each measured direction is the distance from the actual physical direction. Accuracy is largely a system issue and can be affected by mechanical errors such as eccentricity, straightness and flatness. Sensor errors include non-cumulative random variation of the fundamental tone (linear), accumulation of fundamental errors (slope), and variation in the fidelity of the internal sin/cos signal. Precision machine builders typically calibrate for errors with offset look-up tables.

repeatability

The scale of the measurement of the azimuth when the system returns the same physical bearing multiple times. Repeatability is more important than affirmation of accuracy. In order to effectively calibrate for system errors, it is important to keep each azimuth reading consistent. Sensor hysteresis (different readings depending on the direction of approach to the azimuth measured) is an important factor in repeatability.

modularization

The most common way to rotate reaction equipment is encapsulated in a housing with internal bearings and a shaft connected to a motor by a flexible coupling. Enclosures come in a range of sealing levels, and bulky modular devices have no housings or bearings, making it necessary to be built into the mechanical system. They are significantly more compact, but perhaps require a more friendly environment, depending on the skill.

On/off shaft

For rotary applications, the sensor is typically located off-axis on the circumference of the scale around the axis of rotation. When radial space is constrained, some implementations position the sensor on a scale with an axis minimization.

potentiometer

Despite the trend towards non-touch sensors, potentiometers ("potentiometers") are still widely used in low-end applications. A potentiometer measures the voltage drop when a contact slides along a resistive trajectory. They are available in rotary, linear or curved ways and are generally compact and simple. A simple device will cost a few cents, while a more accurate device may cost more than $200. The resistance trajectory is laser-trimmed to achieve a linearity of less than 0.01%.

Potentiometers are best suited for low-performance applications with low duty cycles in benign environments. They are susceptible to abrasion and foreign objects such as dust or sand particles. Potentiometers theoretically have infinite resolution, but in practice the resolution is limited to the analog-to-digital converter (ADC) interface and the entire noise environment.

Advantages: low cost; Simple; Compact; Simple. Be able to be accurate

Disadvantages: wear and tear; Vibration; Pollution, pole temperature.

Position sensor key term – Ottonix

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