Non-Contacting Hall-Effect Rotary Position Sensors

Principles of Operation and Ideal Applications

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Hall-effect Rotary Position Sensors are electro-mechanical devices, used to measure the displacement and position of an object. They are capable of determining angles of rotation by providing feedback in form of a linear signal output which makes them highly suitable for various applications where precise measurement of angular position is essential. 

While some rotary position sensors utilize contacting elements such as a wiper to generate an output signal, these devices are non-contacting thanks to their operating principle and namesake, the Hall-effect.

What is the Hall-effect, and how is it utilized?

The Hall-effect refers to the electrical potential difference across a conducting or semi-conducting material when it is subjected to a magnetic field perpendicular to the direction of the current flow. As current passes through the conductor, the magnetic field will bend the electrons to one side, creating a voltage difference across the conductor&#;s surface.

A typical Hall-effect rotary position sensor consists of a magnetic disk attached to a rotating shaft and a stationary integrated circuit sensing element. As the magnetic disk rotates, it causes a change in the voltage across the sensing element, proportional to the strength and polarity of the magnetic field. The voltage is then used to determine the exact angular position of the target object relative to the sensor&#;s reference point.

Advantages of Hall-effect rotary position sensors

Hall-effect rotary position sensors generally offer a good blend of accuracy and resolution. They produce an analogue output similar to contacting potentiometers, but do so without the aid of physical wiper contact. With no internal contacting parts, these sensors are not subjected to the same degree of mechanical wear and tear as their contacting counterparts, resulting in much longer rotational life spans. As such, applications utilizing non-contacting Hall-effect technology are likely to have their rotational life extended by a factor of at least 20. This also greatly reduces the need for maintenance and service replacement, translating to cost-savings in the long run.

Additionally, Hall-effect rotary position sensors can operate reliably in a wide temperature range, and they are largely unaffected by humidity or dry environments. Shock and vibration exposure has little detrimental effect on their performance, making them excel in static and dynamic applications that operate in harsh, hazardous and/or dirty environments.

Finally, Hall-effect rotary position sensors are often compactly built and can be designed in various factor forms, offering great flexibility. These features make them highly suitable for applications where space restriction is a factor to consider. Overall, Hall-effect rotary position sensors are flexible, reliable and cost-effective with the price range directly tied to the accuracy and rotational life specifications. 

Ideal applications of Hall-effect rotary position sensors

Material Handling Applications where careful positioning and placement of goods, materials and valuables are essential, e.g., fork lifts, cranes and platform trucks, will greatly benefit from implementing Hall-effect rotary position sensors. Asthese applications often operate in locations with varying degrees of environmental influence such as docksides, construction sites, airports and warehouses, the temperature, and vibration resilience of Hall-effect rotary position sensors will certainly come in handy. At the same time, these sensors will provide more than sufficient accuracy and resolution to complete associated tasks - with the added benefits of reducing calibration, maintenance and equipment down time.

Process Automation
Non-contacting rotary position sensors utilizing the Hall-effect are the ideal choice for several process automation applications. Examples of this are valve controllers and actuators, where the sensors enable remote actuation and flow adjustment, and automated robotics systems, where the sensors are used to provide feedback on the position of robotic arms, grippers and other moving parts, ensuring accurate and safe operation. For automated assembly lines where welding and/or soldering are performed, the sensors are also a good positioning solution thanks to their high temperature resistance and overall sturdiness.

Off-Road and Marine Transportation
Hall-effect rotary position sensors often find use in off-road transportation such as construction vehicles and agriculture equipment where they are deployed in e.g., throttle body and position sensing. Their non-contacting nature makes them capable of withstanding great amounts of vibrational forces which is a common occurrence in these fields. Marine applications include boat throttle controls, ship propulsion and rudder position feedback. In challenging sea environments, these sensors provide reliable operation despite changing temperatures and influence of the elements. Their compact design also allows for easy system integration without the need for drastic changes to the overall architecture.

Medical
Applications in the medical field typically include patient table positioning for laser treatment, radiation and/or x-ray as well as patient chairs for laser surgery and dental work. Non-contacting Hall-effect rotary position sensors can provide the accuracy and reliable performance which many high-precision medical procedures are contingent on. The long rotational life cycles and general durability of these products are also greatly beneficial across the global healthcare systems as reduced equipment maintenance and down time will help shortening treatment waiting times.

Today&#;s article is about calipers. Calipers are also called calipers or vernier calipers. Calipers are used to measure inner dimensions, outer dimensions and depth dimensions. More about this in this blog post.

One of the most important tools for thread cutting is the caliper gauge, also known as caliper rule. You can use it to determine diameters, measure core holes in diameter and depth or the distance between two threads, i.e. the pitch of the thread.

Which calipers are available?

There are an incredible number of variants available on the market. There are basically two variants: the so-called analog caliper and the digital version. With the analog version, you read the measurement result on the scale on the caliper. However, you need to know the procedure.

How do I use the analog caliper correctly?

To avoid measuring errors, it is important to master the correct use of the caliper gauge. Correct reading also requires practice.

Nonius scale on analog calipers

The correct reading of the vernier scale. Here we explain step-by-step how to do it. The measuring accuracy is exactly 1/10 mm. The reading device is called nonius. It divides 9 mm into 10 equal parts. One part corresponds to 9/10 mm.

How do I measure with an analogue calliper and the vernier scale?

There are two scales on an analogue calliper: one on the fixed part, one on the moving part. On the fixed scale you read the mm, on the movable scale the 0.1 mm. But how? Well, reading is very simple: you look along the movable scale where a line corresponds to a line on the fixed scale. If it is a smooth mm, then the line at zero is in agreement with the upper scale. For example, if you move the lower scale to the middle of two lines on the upper scale, the result is most likely 5. If you do this between 10 and 11 mm, our measurement result is 10.5 mm. These &#; decimal places &#; are important for example for core hole measurements.

That leaves two questions: why is this so and how does it work?

Imagine, how would you insert further small lines between 10 and 11 mm to determine the decimal places. We would probably not be able to distinguish nine lines in this small space with the human eyes. Therefore, a clever mathematician came up with the idea of introducing this second movable scale. This principle is known as nonius. And now comes the point at which some people would like to bite the calliper: how can I explain this principle in two sentences. We will try it this way, but it is not entirely without mathematics: you all know a row of nine. It goes like this: 9,18,27,36, etc. What stands out? With the first nine you need a 1, with the second a 2 and with the third a 3 to advance to a full ten.

If we transfer this to the calliper, then a tens value means that the lines match. If we move the calliper to the right by 3 units, then we reach the tens value at three. The prerequisite is the following ingenious idea of the mathematician Vernier: he simply made the length unit of the movable scale a little shorter (by 1/100). To get a match, you have to move the calliper to the right to get exactly the length units that are missing on the shortened scale.

Simply put, the vernier is a &#;mathematical&#; magnifying glass mounted on a movable length scale!

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Therefore it does not matter where the movable scale is located. The principle can be applied everywhere, because the ratio of the scales is always 10 : 9.

How do I use the digital caliper correctly?

With the digital calliper the procedure is much more comfortable. Here the measuring result is shown on a display and can be read in plain text. This is very simple. In addition, you can choose between the indication in metric or inches. Some calipers also offer the possibility of transferring the data via an interface. Another advantage is the free selection of the zero point on the measuring scale.

So far, so good. However, two disadvantages should be mentioned. Firstly, you need a battery for the power supply and its capacity is limited, as with all current storage devices. If the digital calliper is not used regularly, the battery will discharge. Please also make sure that the digital calliper switches off automatically. Because people quickly forget to switch it off. Another drawback is system-related:

The digital calliper works on the capacitive linear encoder principle. There must always be a certain distance between the plates of capacitors in the fixed part and the signal generators in the sliding parts. The measuring principle can fail if exposed to dust, water or oil. If you work in such environments, you should remain analog or make sure that the parts are well encapsulated. As a result, you will have to prefer very expensive models.

The way of measuring is the same for both versions:

Error when measuring with the caliper gauge

You should pay attention to the following errors:

• Damage to the caliper gauge
• Tilting the calipers
• Measuring force too strong or too weak
• Incorrect reading
• Measuring on a rotating workpiece
• Contaminated calipers
• Non-compliance with the reference temperature (20 degrees Celsius)

Source: Basic knowledge of metal: technical knowledge &#; technical calculation &#; trade marks of trade and technology

Components of a caliper gauge

• Fixed limb
• Movable leg
• Clamping screw
• Slider
• Nonius scale
• Slider
• Ruler
• Cutting edges for measuring incisions

You can find calipers HIER in our shop

Conclusion: Digital or analogue calliper?

&#; Advantages of the digital calliper:

• &#; Convenient and fast reading
• &#; Metric and inches

&#; Disadvantages of the digital calliper:

• &#; Battery for power supply
• &#; Not resistant to dust, water and oil

&#; Advantages of the analogue calliper:

• &#; Robust and durable

&#; Disadvantages of the analogue calliper:

• &#; Practice reading the vernier scale

Calipers are available in our shop:

Caliper gauge &#; How do I measure threads?

To determine the thread you need a caliper gauge to determine the diameter of the thread.

Please read our instructions:

If you have specific questions, please do not hesitate to contact us.

For more information, please visit Non-contact rotary caliper.