Quantifying CRS Fit in the Vehicle Seat Environment – Digitization Approach (Multiple Year Project)
Principal Investigator: Aditya Belwadi, PhD, The Children's Hospital of Philadelphia
The challenges and frustration faced by many parents and caregivers in installing child restraint systems (CRS) has been well-documented, both scientifically and in the lay media. The evolving nature of CRS design (and an increasing amount of CRS options for consumers) puts pressure on vehicle manufacturers to keep their vehicle seats and occupant space compatible. This multi-year CChIPS project aims allows vehicle manufacturers to understand the breadth of CRS dimensions and to take them into account when designing new vehicles.
Researchers developed a methodology for digitization of CRS and created a virtual surrogate of a small rear-facing CRS -- a volume encompassing CRS to aid designers in assessing space and fitment during the design phase of the vehicle rather than an “aftermarket” assessment, which has typically been the standard. They leveraged the capabilities of the Microsoft Xbox Kinect Sensor™ for this purpose as a cost-effective alternative to more expensive technology.
Virtual installation of the “surrogate” (in blue/green) in a sub-compact sedan.
Year 1: 2013-2014
Year 1 of this project developed a methodology for CRS digitization by creating a virtual surrogate of a small rear-facing CRS – a volume-encompassing CRS to aid designers in assessing space and fitment during the design phase. This was accomplished by using the Microsoft Xbox Kinect Sensor™ to scan 72 CRS, including rear-facing, forward-facing, high-back boosters, and low-back boosters, to represent 252 CRS commercially available as of April 2013.
The drawings in several electronic formats were made available to vehicle and CRS manufacturers that are members of CChIPS to conduct a “virtual fitment” study in their design environment to evaluate interference and compatibility. The virtual surrogate was installed in both outboard and center seating positions of a sub-compact passenger car, compact sedan and compact SUV in various combinations of fore-aft positions of the front seat.
Initial vehicle and CRS manufacturer feedback of this process indicated several points: 1) that the rear-facing virtual surrogate accurately predicts the interferences seen in typical physical installations of these child seats in most seating conditions; and 2) that there is a need to expand the surrogate to include larger rear-facing CRS, convertible CRS, and forward-facing CRS and both high/low back boosters.
Year 2: 2014-2015
In Year 2, researchers again utilized the Kinect Sensor in conjunction with ReconstructMe, which used the real-world imaging data read by the Kinect to create a three-dimensional shell file. This file was then imported into Hypermesh, a high-performance finite element pre-processor, for clean-up and full-model construction. Finally, a “shrink wrapping” process in Hypermesh was used to create a single, final shell that encompassed the model and yielded an accurate virtual CRS. The same shrink-wrapping process was then used to combine multiple CRS into virtual surrogates to represent groups of CRS on the market according to size, shape and geometry.
Six virtual surrogates were developed based on the combination of scanned and original equipment manufacturer CRS virtual models. Additional CRS were scanned in Year 2, resulting in a total of 48 rear-facing seat models representative of 81 on the market, 69 forward-facing seat models representative of 104 on the market, and 35 high-back booster and 22 low-back booster models included over the duration of Year 1 and Year 2 of this project.
Through two years of development, the virtual surrogate has been proven to be an effective tool in assessing CRS-to-vehicle fitment. Feedback from both vehicle and CRS manufacturers have further helped transform these models from amorphous “blobs” to “surrogates,” accurately representing the volume of child seats. The next phase of this project will expand the virtual surrogate development to include additional seat types and sizes. Additional data on seat recline angles and belt paths will be added to aid fitment assessment.
The above images depict virtual surrogate models, from rear-facing child restraints (RF) in Year 1 extended to
forward-facing child restraints (FF), high-back boosters (HBB) and low-back boosters (LBB) updated for Year 2.
Year 3: 2015-2016
Automotive interior design optimization must balance the design of the vehicle seat and occupant space for safety, comfort and aesthetics with the accommodation of add-on restraint products such as child restraint systems (CRS). Because CRS design is constantly changing, particularly with the introduction of CRS side impact protection and emphasis on ease of installation, the onus is on vehicle manufacturers to keep vehicle seats and occupant space compatible.
This multi-year line of research aims to allow vehicle manufacturers to better understand the breadth of CRS dimensions and to take them into account when designing new vehicles. In Year 1, a methodology was developed using the Microsoft Xbox Kinect™ sensor to scan commercially available CRS to create a volume-encompassing virtual surrogate of a small rear-facing (RF) CRS. Additional CRS were scanned in Year 2, resulting in a total of 48 RF seat models representative of 81 on the market, 69 forward-facing (FF) seat models representative of 104 on the market, and 35 high-back boosters (HB) and 22 low-back boosters (LB) models included over the duration of this project.
In Year 3 of this project, 28 additional CRS were scanned using the Kinect™ sensor along with 22 OEM drawings to represent over 293 CRS on the market as of March 2016. Further, 18 vehicle model scans were conducted to place the CRS surrogates in the context of an actual vehicle installation. The relevant scanned drawings were then overlapped for installation on an exemplar vehicle seat pan and seat back angle to create virtual surrogates of small, medium and large RF, FF, HB, and LB CRS models. The models included all of the seat belt paths, orientation denotation and level to ground markings, and were made available to CChIPS IAB vehicle and CRS manufacturers as finite element models and surface data sets. Vehicle and CRS manufacturers provided detailed feedback on the utility and accuracy of the surrogates.
Year 3 concludes this broad line of work to quantify and characterize the shapes and volumes of a significant number of CRS (293 in total) on the United States market. The virtual surrogates can be used by both the vehicle and CRS manufacturers to assess fitment in the design environment early on in their production cycle. The ultimate goal is that this will translate into designs that lead to better CRS-to-vehicle fitment, less misuse and enhanced occupant safety.
CChIPS Virtual Surrogate Models: Three each of RF (Small, Medium and Large),
FF (Small, Medium and Large) and one each of HB and LB were developed.
Richard Hanna, MS, Drexel University (Y2,Y3); Evan Bisirri, Drexel University (Y3); Daniel Martinez, Drexel University (Y1)
Doug Longhitano, American Honda Motor Co., Inc. (Y1,Y2,Y3); Keith Nagelski, Britax Child Safety, Inc. (Y1,Y2,Y3); Eric Dahle, Evenflo Company Inc. (Y1,Y2,Y3); Audrey Eagle, FCA US LLC (Y1,Y2,Y3); Julie Kleinert, General Motors Holdings LLC (Y1,Y2,Y3); Mark La Plante, Graco Children’s Products Inc. (Y2,Y3); John Combest, Nissan Technical Center North America Inc. (Y2); Schuyler St. Lawrence, Toyota USA (Y1,Y2,Y3); Barbara Birkenshaw, Volkswagen Group of America (Y1,Y2,Y3); Uwe Meissner, Technical Advisor (Y2,Y3); Eric Eisenworth, Ford Motor Company (Y1); Michelle Tsai, Consumer Reports (Y1); Rajiv Menon and Terry Emerson, Dorel Industries Inc. (Y1); John Bachner, Graco Children’s Products (Y1);Emily Thomas, Consumer Reports (Y3); Arjun Yetukuri, Lear Corporation (Y3).