ERL Seat Design – Occupied Specifications for the Unoccupied Deliverable Seat

A digital human body model is used to mathematically calculate occupant position in the vehicle package. The unoccupied seat shape that will support the digital human body model is optimized using a biomechanical model of the human body, a load-deflection model of the seat along with manufacturability and safety criteria. By unloading the seat at anatomically comparable landmarks for each digital human body model, as defined by gender and body size, the collection of points on the unoccupied seat surface define a patch. With 3 patches on the cushion and 4 patches on the back, two surfaces representing the centerline of the seat and seat insert can be defined for the population of occupants. This process can be done with constrained or unconstrained vehicle package geometry. The result is a “one seat fits all” design of the unoccupied deliverable seat given the requirements of the ergonomic task of driving the vehicle. With the specification of the unoccupied seat surface, a three-dimensional physical template can be constructed that will verify if the delivered seat property meets the original seat math specifications. The only issue remaining is measuring the occupied seat for the human occupant. This performance assessment is made through the use of a load-deflection measurement to assess cushion and back stiffness. If the delivered seat as defined by the trim, foam and suspension acting in series meets the load-deflection characteristics of the design, then the occupied seat in the vehicle will perform for the human occupant as the unoccupied seat design performs for the human body model.