BioMechanical Design Design of a new transformation device for a tip seat for multifunctional public transportation

Tribus b.v. is a company in Utrecht that converts minibuses for multifunctional public transportation. This means that with the same bus both ambulant people and wheelchair occupants can be transported. The multifunctionality lies in the combination of a flexible floor layout and (tip) seats. The floor system is based on separate aluminium profiles that are assembled to form any desired floor layout. Tribus’ tip seat (FlexusPRO) meets the highest quality and safety requirements. Because of its integrated three point safety belt, the seat can be positioned anywhere in the vehicle. A common seat layout is the 4x4 tip seats, where four FlexusPRO seats are positioned on the right side of the vehicle and four on the left. By folding the seat pan to the backrest and subsequently rotating the seat package to the side, a wheelchair environment is created without removing or repositioning the seat. This transformation from passenger seat (mode 1) to wheelchair space (mode 2) is an easy and fast operation that enables the transporter to do a combined transportation of ambulant people and wheelchair occupants with the same vehicle. Besides the benefits of Tribus’ FlexusPRO, the tip seat also has some main drawbacks with respect to the production costs, weight, the available wheelchair space after seat transformation and the hindered view outside for the wheelchair occupant as a result of the seat dimensions in mode 2. The goal is to overcome these drawbacks, in order for Tribus to be able to launch a new tip seat that exceeds seats of competitors on price, weight, operation and functionality. The goal of this graduation project focuses on the improvements of the seat position in mode 2. This means an improvement of the transformation device, where the overall goal is to reduce the production costs and weight by at least 30% and increase the view outside for the wheelchair occupant by at least 20% in combination with an increased lateral wheelchair space of at least 10%. However, in order to obtain a good design, a complete concept of the new tip seat needs to be proposed, where every aspect of the seat is able to fulfil the design requirements. A morphological approach resulted in three tip seat concepts that are rated with respect to usage and manufacturing aspects. The final concept led to a tip seat with a rotation device and a tilting backrest, that increases the lateral wheelchair space in mode 2. The improvement of the lateral wheelchair space is however dependent on the entire seat design, where the base frame of the seat will be leading. Because the base frame of the seat is not part of this project, a specific percentage of the improvement is not yet known, but an improvement of at least 10% can be realized. The separate headrest of the seat is moved down during the transformation to mode 2, which improves the view outside for the wheelchair passenger. The entire seat design is also not part of this project, but research on commercial vehicles showed that a vertical adjustment