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Seat Comfort Measurement & Testing

Of all the factors car buyers consider when deciding on their next vehicle, seat performance isn't high up in the list typically. But for all drivers, especially those who have back pain or who regularly drive long distances, a comfortable and supportive seat is just as important as other factors such as reliability, fuel economy, safety and styling. It's tough to enjoy a vehicle when driving causes physical discomfort.

Unfortunately, finding the right seat may not be as easy as comparing fuel economy or safety ratings. There is no perfect seat for every driver. It depends on a multiple factors such as:-

  • Driving Position,
  • Lumbar Support,
  • Leg Support, &
  • Other Seat Features- legroom, shoulder room, seat adjustment options etc.

Thus, testing for driver seat comfort is complex and challenging because it is somewhat subjective in nature (e.g. position, human mood, seat features). However, there are certain aspects of a seat comfort, which are objective (e.g. electromyography, anthropometrics, pressure distribution on seat) and can be modelled mathematically.

Below are some effects/causes of seating discomfort:-

Causes and Sources of Seat Discomfort

Automotive Seat Comfort Factors

Research has shown that some of the main factors that affect seating comfort are-

  • Seat-interface pressure distribution
  • Whole-body vibration
  • Pressure change rate
  • Body Posture

Studies of comfort rely on seat pressure measurement at the interface between the seat and human body part.

For instance, a greater uniformity on the seat pressure distribution, a lower peak of pressure and a wider and more symmetric contact surface area lead to improved seat comfort. Lower rates of pressure on the buttocks and higher on the back together with balanced pressure among buttocks, upper part and lower body lead to better seat comfort.

Points to be checked during automotive seat comfort measurement

Back Support

  • Amount of lumbar support
  • Amount of mid-back support
  • Amount of back lateral support
  • Seat back feel/firmness

Cushion

  • Ischial/buttocks comfort
  • Thigh comfort
  • Cushion lateral comfort

Objective Automotive Seat Comfort Measurement

  • These are few parameters and methods in which a seat can be evaluated objectively for its comfort.
  • In these, mostly seat pressure mapping is used to study the discomfort feeling. This method is the most used method for seat developers to measure the seat comfort and discomfort of seated person.
  • The instruments that are used in seat pressure mapping are pressure mat, pressure monitor system , force sensor, seat deformation measuring device and pressure imaging system.
  • Advanced Structures India uses the above seat pressure mapping method to objectively evaluate automotive seats using pressure mapping sensor. We follow a methodology which is used to correlate the objective and subjective evaluation & this enables us to compare, rank and rate the seats comfort.

Testing instruments used for Seat Pressure mapping

Pressure Mapping- Pressure Mat & Evaluation Sensor

This is the pressure mat which is properly placed on the seat & the subject is seated over it to measure the useful data such as pressure, contact area, force etc. which is interpreted using various algorithms.

Testing Overview:

Seat Pressure Mapping

Measurement of pressure exerted at cushion & back along gives us a seat pressure map on the display screen which is further processed on the software to obtain the valuable data such as minimum, maximum & peak pressures, contact area, etc. at cushion & backrest on the basis of which a seat can be rated objectively.

Seat Pressure Map generated after Testing

Above seat pressure map represents various areas where the pressure varies and further returns a numeric value for amount of pressure which is helpful in finding a comfortable automotive seat. Here different colours represent different pressure zones where red is the maximum. This is one of the best & widely accepted methods to evaluate the automotive seat comfort.

Subjective Automotive Seat Comfort Measurement

The subjective evaluation is as equally important as the objective measurement to evaluate the seat for its comfort. Its protocol involves highly structured questionnaires. The questionnaires direct occupants to assign feelings of discomfort to a specific region of seat. The questionnaires, which typically contain numeric scales (e.g. 1 = very uncomfortable to 10 = very comfortable), produce subjective ratings that are translated into performance requirements/specifications.

Passengers on a car seat can be surveyed to measure the seat comfort level and identify which features lead to higher comfort level.

Subjective measurement also involves the use of body mapping technique. In this the subject will be rating the body areas experiencing discomfort and to rate this discomfort on a scale.Parameters for Seat comfort evaluation-Subjective Measurements

Conclusion

Thus, we can say that seat pressure distribution method is the most common method for objective measurement of automotive seat comfort understanding. It is followed by posture analysis method & the local discomfort rating. But, alone objective measurement can't be used to judge a seat for its comfort. It must be supported with the proper subjective evaluation of the automotive seat.

At Advanced Structures India, we have developed methodologies and database of Indian car seats to compare the seats across the segments. Our innovative seat comfort measurement methods compare any new seat with the existing seats in the market using our database or from the customer specific seat benchmark category in less time with more accuracy.

Small tip for any car buyer to quickly evaluate a comfortable seat

A test drive is really one of the most important ways to know if a vehicle has the comfortable seat and to find it out you might need to take a long test drive. Make sure your test drive is at least 30 minutes which can  give you an idea about the seat comfort.

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Ashish Kumar


Advanced Structures India Pvt Ltd is an independent automotive product development company based out of Bangalore, India with operations in India, China and US. Above is a blog entry from our engineers about Seat Comfort Evaluation. We can be contacted on business@advancedstructures.in for business enquiries and careers@advancedstructures.in for open positions.

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