H-point

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The H-point (or hip-point) is the theoretical, relative location of an occupant's hip: specifically the pivot point between the torso and upper leg portions of the body — as used in vehicle design, automotive design and vehicle regulation as well as other disciplines including chair and furniture design.

In vehicle design, the H-point is also measured relative to other features, e.g. h-point to vehicle floor (H30)[1] or h-point to pavement (H5). In other words, a vehicle said to have a "high H-point" may have an H-point that is "high" relative to the vehicle floor, the road surface, or both.

Technically, the h-point measurement uses the hip joint of a 50th percentile male occupant, viewed laterally,[2] and is highly relevant to national and international vehicle design standards such as global technical regulations (GTR). For example, a vehicle design standard known as the Society of Automotive Engineers (SAE) J1100 Interior Measurement Index sets parameters for such measurements as H30 (H-point to vehicle floor); H5 (H-point to pavement surface), H61 (H-point to interior ceiling) and H25 (H-point to window sill).[3]

See: H30, H5, H61 and H25 Diagram

As with the location of other automotive design "hard points," the H-point has major ramifications in the overall vehicle design, including roof height, aerodynamics, visibility (both within the vehicle and from the vehicle into traffic), seating comfort,[4] driver fatigue, ease of entry and exit,[4] interior packaging, safety, restraint and airbag design and collision performance; as an example, higher H-points can provide more legroom, both in the front and back seats.[3]

By the early 2000s there had been a global trend toward higher H-points relative to the road surface and the vehicle's interior floor.[5] Referring to the trend in a 2004 article, The Wall Street Journal noted an advantage: "the higher the H-Point, the higher you ride in the car, and in some cases, the more comfortable you feel behind the wheel".[3]

Buses, minivans, SUVs and CUVs generally have higher H-points (relative to the road surface and the vehicle interior floor) than sedans, though certain sedans feature higher H-points than most, e.g., the Ford Five Hundred, Fiat 500L. Sports cars and vehicles with higher aerodynamic considerations, by contrast, may employ lower H-points relative to the road surface; when an automobile features progressively higher H-points at each successive seating row, the seating is called stadium seating, as in the Dodge Journey, and Ford Flex.[4]

Vehicle interior ergonomics are integral to an automotive design education; the Society of Automotive Engineers (SAE) has adopted tools for vehicle design, including statistical models for predicting driver eye location and seat position as well as an H-point mannequin for measuring seats and interior package geometry. See SAE J86 for a description of the H-point machine. Occupant posture-prediction models are used in computer simulations and form the basis for crash test dummy positioning.[6]

Regulatory definition: For the purpose of U.S. regulation and GTRs (Global Technical Regulations) – and for clear communication in safety and seating design[7] – the H-point is defined as the actual hip point of the seated crash test dummy itself,[7] whereas the R-point (or SgRP, seating reference point) is the theoretical hip point used by manufacturers when designing a vehicle – and more specifically describes the relative location of the seated dummy's hip point when the seat is set in the rearmost and lowermost seating position.[7]

See also[edit]

References[edit]

  1. ^ "2004 Mitsubishi Outlander New Car Test Drive". Car.com, Larry Edsall.
  2. ^ "Dept of Transportation NHTSA Federal Motor Vehicle Safety Standards" (PDF). Federal Register May 4, 07 p.25485.
  3. ^ a b c Michelle Higgins (December 2, 2004). "Riding High: Auto Makers Jack Up the Car Seat; Finding Your Ideal 'H-Point'". The Wall Street Journal. Archived from the original on May 2, 2008. Retrieved March 13, 2017.
  4. ^ a b c "2005 Ford Freestyle Design". Myfordfreestyle.com.
  5. ^ "Frankfurt Motor Show: Will getting more into less become more out of less?". Automotive Engineering International Online, Stuart Birch, European Editor.
  6. ^ "Vehicle Ergonomics Laboratories". U. Michigan Transportation Research Institute.
  7. ^ a b c "NHTSA's Activities under the United Nations for Europe 1998 Global Agreement: Head Restraints, Docket NHTSA-2008-001600001". NHTSA.

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