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Universal Technical Challenges in IMUs

As sensors continuously enhance our everyday interactions with technological devices, glitches in these applications can interfere with the user experience. Our latest blog explores universal technical challenges with sensors and the UX issues they create. 

Monday, December 10, 2018

IMU sensor technology is becoming nearly ubiquitous today, and it’s changing the consumer electronics and industrial automation markets. Sensors already enable or enhance many of your daily interactions with tech—from helping your robotic vacuum cleaner navigate your house, to producing true-to-life experiences when playing the latest VR video game, to ensuring the high-quality network connections you enjoy on your smartphone. However, sometimes these applications have glitches that interfere with user experience.

Exploring real-world user challenges:

Robotic vacuum cleaner performance problems

When robotic cleaners can’t navigate accurately, they frustrate consumers by getting lost in a random corner of the home, getting stuck on furniture, or failing to clean certain parts of a room. All of these issues lengthen the cleaning process and damage the user experience.

VR issues with motion sickness

In VR, motion reproduction and low latency are key metrics. A system missing one or the other creates a visual lag that makes what the viewer sees fall out of alignment with what their other senses are reporting. And when that happens, users can end up with motion sickness and a bad overall experience.

Antenna point-of-installation issues

When wireless companies add new areas of service, they will mount new antennas to structures and poles, and align them with a particular point. Calibrating and maintaining the correct orientation on the installation point keeps the network performing at its best and can help reduce physical check-ups by a technician.

When user experience is compromised due to challenges with sensors, you could end up with a floor that never got cleaned, nausea from your VR experience or connection issues in your data transmissions.

Defining the sensor challenges

In order to correct for universal sensor challenges, it's important to identify what they are in the first place.

Since they are composed of mechanical parts that are incredibly small (microns in size), sensors aren’t able to be manufactured with absolute consistency from unit to unit. This manufacturing limitation leads to statistical measurement anomalies. These anomalies are then exacerbated by common environmental factors, like temperature. This combination results in sensor performance inconsistencies and the poor user experiences mentioned earlier.

Even when engineers are able to identify technical anomalies, they often don’t have the expertise to account for these anomalies in their sensor calculations. These challenges can be conquered using a combination of data collection, analysis, and software.

What causes inconsistent sensor output?

All sensors are prone to statistical anomalies, including:

  • Gain: the sensitivity measuring how much the output will change when the device moves
  • Offset: a shift in the output that is independent of the motion
  • Non-linearity: change in the gain that depends upon the speed of motion
  • Cross-axis: the output that is not in the direction of motion. It is sometimes useful to analyze the cross-axis effects to distinguish between rotation and skew:
    • Rotation: the orthogonal rotation between the input motion axes and the output axes
    • Skew: the remaining cross-axis output that can’t be explained by an orthogonal rotation
  • Noise:  any output that is not explained by the above effects.

 

 Char of inconsistent statistical outputs from sensors

 

When accounting for these inconsistent statistical outputs from sensors, it's important to also measure and account for the following external environmental factors:

  • Temperature: change in sensor parameters due to changes in temperature. These will often be linear. Sometimes they are non-linear and can have hysteresis, where the value depends upon not only the current temperature, but the history of temperature
  • Voltage: change in the sensor parameters due to change in the sensor voltage applied to a sensor, within its operating range
  • Operating mode: change in sensor parameters and operation due to different modes (i.e. low power vs. performance mode).
  • Aging: change in the sensor parameters over time and not explained by any of the previous conditions.

Over time, these external environmental factors exacerbate the universal sensor anomalies already described. This leads to degraded performance and a shortened sensor lifespan.

How do sensor challenges impact your bottom line?

Stretched resources slow your time to market

Companies can spend hundreds of man-hours and thousands of dollars in R&D trying to solve sensor challenges. This is compounded when they try to enable sensor fusion with limited expertise.

Opportunity costs hurt innovation elsewhere

In a fast-paced technology landscape, user experience and product innovation are critical factors in future adoption. Time and money otherwise lost solving sensor challenges can be better spent on developing product innovation to maintain a competitive edge.

Poor performance damages your brand

Failure to truly solve these sensor challenges leads to non-competitive products, user-experience nightmares or total product failures. Ultimately, this leads to a loss of trust in your brand.

Enabling the sensor solution

Over the last 15 years we have investigated these sensor challenges and designed sensor fusion software solutions. We developed a proprietary Sensor Qualification Test System (SQTS) that collects data over a wide range of motions with varying environmental effects, all with statistically significant spread (210 sensors at once). By analyzing this wealth of information, we are able to update our sensor fusion algorithms to dynamically account for environmental impacts. The result is a more cost-effective sensor that performs just as well as its much more expensive counterparts.

The right sensor manufacturer identifies and addresses anomalies early on so that their application partners can realize a better user experience. And that's important because growing demand in consumer electronics, coupled with the increasing industrial applications enabled by rapidly advancing capabilities means that even more companies will need reliable sensor technology in the future.