RESUMO
Musculoskeletal sitting discomfort, specifically caused by long-term sitting, is primarily triggered by physiological fatigue on the human body due to its own weight. Passive seat designs can produce inadequate surface pressure zones on the body resulting in high musculoskeletal stress leading to physical discomfort. However, as proposed in this work, this can be alleviated by decentralizing the occupant's weight with an automatic morphing lumbar seat design. The morphing seat design presented in this paper adjusts in real-time, the seat's surface curvature to decentralize the pressure distribution. The seat system consists of a custom-made pressure sensor mat embedded within the backrest cushion and two pneumatic actuators located in the lumbar area. The purpose of this seat design is to produce a change in the backrest surface curvature so that such change creates a pressure distribution closely resembling a reference distribution. Said reference distribution is derived in this work based on the concept of the Ideal Pressure Distribution. The effectiveness of the discomfort reduction due to the decentralization of the backrest load is evaluated using an objective discomfort metric known as Seat Pan Distribution percentage applied only to the backrest, peak pressure areas and contact area. Preliminary performance tests of the seat system demonstrate the successful decentralization of the passenger's pressure distribution. The evaluation of the discomfort reduction is observed via the lowering in the objective discomfort metric and peak pressure areas while simultaneously increasing the contact area between the passenger and seat.
