What position is this thing in?

Associated questions could include: Has it moved? In what type of motion? How close is it?

While accelerometers, gyroscopes and magnetometers provide inertial measurement units (IMUs) for position sensing in smart phones and other portable products, many other sensing technologies have been used to determine position, long before the smart phone.

In industrial applications, more commonly used technologies include:

• Capacitive
• Eddy current killed oscillator (ECKO)
• Electrolytic
• Hall effect
• Inductive
• Linear Variable Differential Transformers (LVDTs)
• Magnetostrictive
• Multi-axis displacement transducer
• Photodiode array
• Piezo-electric transducer (piezo-electric)
• Potentiometric
• Proximity sensor (optical)
• Resolvers
• Rotary encoder (angular)
• Rotary Variable Differential Transformers (AC RVDTs)
• Rotary Variable Inductive Transducers (RVITs)

In fact, a recent report projects that the position sensor market is expected to reach USD 5.98 Billion by 2022, increasing at a CAGR of 6.27% between 2017 and 2022. Robotics is one of the industrial areas that provide a prime driver for position sensors. Others include:

• Test Equipment
• Material Handling
• Machine Tools
• Motion Systems

An earlier report forecasted that the global market for position sensors is projected to reach US$11.3 billion by 2020, driven by the growing popularity of advanced smart position sensors. The significant discrepancy in the two forecasts mainly involves the exclusion (recent) or inclusion (earlier) of smart phone position sensing. In any case, the growth is significant.

Companies that design and manufacturer position sensor often offer more than one type. Their websites frequently provide an advantages-disadvantages comparison of the types of sensors they offer.

Key parameters for specifying a position sensor include:

• Measurement type
  • Linear or rotary
  • Incremental or absolute
• Form factor
• Mounting
• Resolution,
• Repeatability
• Linearity
• Operating and storage temperature range, and
• Electrical output

There are many technology choices for position sensors. Choose wisely and you’ll be in the right position.