Interesting applications from the automation industry

Sensors often play a very important role in automation technology. Sensitec MagnetoResistive sensors are used in many applications, such as simple switching functions in pneumatic cylinders, highly dynamic and high-resolution motor feedback systems or even in complex process monitoring. These deliver flawless, high-precision measurement results to the upstream control unit.

Due to the variety of requirements, all possibilities and benefits of magnetic sensor technology are fully utilized in automation. These include durability, precision and dynamics as well as high signal resolution, a broad temperature range and naturally also the possibility of extremely compact sensor integration.

In the following descriptions of use you will find various examples of how and where Sensitec MagnetoResistive sensors are used as a solution for measurement tasks.

Further applications

Further applications

Position and speed measurement Measurement system to record the angular position and speed of the motor shaft

Background

Local solutions, high power density and cost efficiency are the demands that are also being called for in the field of development of electric motors. The high integration density and the simultaneous increasingly harsh conditions, pave the way for magnetic solutions. Dust, oil and grease cannot touch the magnetic measurement principle – integration without any housing is preferable to avoid unnecessary costs as well as the space saving. The high power density leads to higher temperatures and also to larger magnetic stray fields. The challenges for a customized measurement solution for recording speed and position are extremely complex and can only be solved reliably with a special design.

Sensor solution

  • Compact sensor module with an AL796 AMR FixPitch sensor for a high installation tolerance.
  • Reference signal is implemented using a GMR field sensor which also allows a large sensor distance.
  • Signal conditioning and conversion into a digital quadrature signal using a specially coordinated interpolator.
  • The sensor module is integrated near the power electronics, just above the motor winding – as such, no additional space is needed at the end of the motor.
  • With compact plastic bonded hard ferrite pole ring with 32 poles – resulting in up to 8192 measuring steps per rotation.
  • Speeds of up to 8,000 rpm are possible.

Advantages

  • Low cost and extremely compact
  • Broad range of temperatures up to +105°C and large installation tolerances
  • High measurement resolution and accuracy of approx. ± 0.35°
  • Extremely durable in harsh environmental conditions
  • Sensor module can be used flexibly with a power supply of either +3.3 V or 5 V.

Project request

Angle measurement robots Angle measurement in the motors of robotic joints

Background

The changing face of industrial robotics: The image of classic industrial robots – that perform their services on heavy and cumbersome components, locked in cages in order to protect the life and limb of the employees in the area should a malfunction occur – is a thing of the past in the new generation of robots. The trend is towards "collaborative work" – not just between people, but also between people and robots. If robots can indeed easily carry larger loads and operate as delicately as a human being using modern sensor components, then they can learn the motion sequences of people – “hand in hand” in the truest sense of the phrase. With their strength, they can assist people in adjusting and exact positioning of components in the mounting processes. More fields of use are being revealed practically every day.

Sensor solution

  • AL797 AMR FixPitch sensors for the highest performance and minimization of mechanical influences.
  • The system concept generates vernier signals adapted to the motor for further processing in the controller.
  • Extremely simple implementation of the assembly design for integration in the motor.
  • The assembly has storing components for sensor parameters. These are recorded during production and saved in the module. The controller can select these and use them for correction calculations.
  • The assembly delivers the amplified raw sensor signals and has been certified for the system with SIL3.

Advantages

  • Extremely high sensor signal performance for positioning and torque control
  • Very compact integration with flat construction and a very durable design adapted to the application
  • Safety applications possible thanks to SIL3 certification

Project request

Process controls & process documentation Process monitoring for mechanical riveted joints

Background

It pops and is over in less than 500 µs: A nail-like "tac" joins two materials together - and the whole thing is absolutely perfect! The connection is stable – which can be seen very easily in a diagram – because the fusion process is monitored by sensors. But take a step back: What’s this all for?

Plastic bonded materials are increasingly being used in modern car body production, meaning that classic welding technology is no longer an option. Riveted joints have the disadvantage of requiring a counterpart in order to produce a safe connection. As a result, a new joining method has established itself, which closely resembles a nail connection. Due to the high demands for a demonstrably secure connection, the process must be monitored and documented. 

This requires a measuring and evaluation system, which virtually completely records the joining process. The analysis is carried out using a systematic "fingerprint”. Driving in the tac too strongly or too weakly results in an unclean connection and can be clearly recognized by a number of points in a recorded distance-time diagram. The same is true for a correct, clean join.

At a speed of more than 50 m/s, the roughly 3-cm-long tac is "shot" into the materials - a highly dynamic process that places high demands on the sensor solution.

Sensor solution

  • The compressed air driven driver piston for the tac features a 2-mm tooth structure. This is sealed with a non-magnetic material so that the piston has a smooth surface.
  • The sensor system, based on the GMR tooth sensors, was integrated in the piston guide. 
  • The sensor signals are amplified and sensor parameters, such as offset and amplitude, are corrected.
  • Within the controller, the position of the piston can be determined using a simple arc tangent procedure and can be converted into a distance-time diagram in combination with the time.
  • The assembly is extremely durable and is implemented in the system so that it can withstand the strong shock loads despite harsh conditions.

Advantages

  • Excellent sensor signals despite high dynamics in the process
  • Direct measurement principle on the driver piston is presented precisely via the tac-position
  • Distance-time diagram or “Finger print” of the process for high-quality proof of quality
  • Resistant to strong shock loads and dirt

Project request

Current measurement in drive controllers Typical high-resolution, 3-phase current measurement with galvanic isolation

Background

There are numerous options with a wide range of technologies for typical 3-phase current measurement in the field of drive technology. In principle, the requirement consists of ensuring a secure galvanic isolation between the load circuit and the signal circuit. Furthermore, good dynamics, low power losses and low installation space are required for current measurement.

The better the current measurement, the higher the control quality of the overall system. However, cost-effectiveness is also required. A cheap transformer often requires extensive wiring – so all the pros and con of the overall system must always be weighed up.

Sensor solution

  • Standard current sensor of the CDS4000 family with unipolar 5 V power supply.
  • 3 sensors with compact outer geometry for all 3 phases.
  • The current sensors are fitted onto the PCB as a THT component and no addition cables leading through the converter core are required.

Advantages

  • High signal bandwidth with 200 kHz
  • No iron core, very compact structure, hardly any internal losses
  • Current proportional analog output signal
  • Additional overcurrent output signal for direct shut down of the IGBTs

Project request

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