Ricard Barberà i Guillem, Helios de Rosario Martínez(*), Ignacio Bermejo Bosch(*), José S. Solaz Sanahuja, Laura Martínez Gómez; Alicia Piedrabuena Cuesta; José Montero Vilela, Carlos Chirivella Moreno

Instituto de Biomecánica de Valencia

(*) CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN)

The aim of the CARGO project (FP7- SME -2010-1-261894) was to create a solution which allowed individuals with reduced mobility to access small utility vehicles in a convenient, independent manner. To do so, a wheelchair was developed which could be folded to fit into the space usually occupied by a car seat, as well as a mechanism to pick up the wheelchair and the seated user and transport them to the inside of the vehicle. One of the most critical points was the study and analysis of the trajectory of the wheelchair and user's movement from outside the vehicle to inside the vehicle, and vice versa. The trajectory had to be collision free, ensure optimal displacement, and be adaptable to different platforms and users. This article presents the most salient aspects of the trajectories and collisions study.

INTRODUCTION

The majority of vehicle adaptations for wheelchair users are currently based on ramps, transfer platforms or robot arms, which only take in the wheelchair once the user is seated inside the vehicle. These solutions entail the adaptation of large, expensive vehicles; they also reduce the number of passengers that can travel in the vehicle and are often only suitable for individuals with a high level of autonomy.

The drawbacks inherent to existing solutions led to the launch of the CARGO project, aimed at offering a solution which would allow wheelchair users to access family cars independently, without the need for passenger space to be reduced.

With this aim in mind, the CARGO project developed three main elements: (1) a system for anchoring the wheelchair to the bodywork, (2) a transport mechanism to allow the user and wheelchair to enter/exit the vehicle, and (3) a collapsible wheelchair that can be used both as a conventional electric wheelchair and as a car seat.

Figure 1.Overall view of the prototype. During access (left) and in the anchored position (right).

The companies who participated in the CARGO project were CONSTABLES (United Kingdom), Mess BVBA (Belgium), HAPTE (France) and SALVIO BUSQUETS (Spain), along with the technological centers HERI (United Kingdom) and IBV (Spain).

One of the most significant constraints in the development of the system was the use of space in the entry/exit maneuvers. Crucial in overcoming this constraint was the definition of an optimal trajectory for preventing collisions between the volume made up of the user and the wheelchair and the passenger compartment of the car. Among other activities, the IBV led the project in this area, prior to the development of a suitable transporter.

DEVELOPMENT

The transport mechanism has five degrees of freedom, or movement possibilities, consisting of: height displacement, three types of longitudinal displacement, a rotation and a tilting movement. Figure 2 shows these six movements along with a representation of the user's package volume.

Figure 2. Detail of the system's basic movements.

Before calculating the trajectory, the packaging requirements needed to be defined by determining the combined volume of the user and the wheelchair, as well as the volume of the passenger compartment, paying special attention to the pillars and the dashboard. Figure 3 shows the key measurements of the CARGO user-wheelchair ensemble.

Figure 3.Key measurements of the user-wheelchair ensemble.

For the development of the project, the front passenger compartment was digitalized for ten different models of car. The volume of the CARGO wheelchair/user package was also calculated.

The algorithm developed for actuator operation was based on incremental orders with a combination of the different rotation, tilting and displacement strategies. If any collision was possible, the next movement was not started. Figure 4 shows the tilting movement for exiting the vehicle's passenger compartment required to pass under the upper height limit of the door frame.

Figure 4.Side view of the tilting movement employed to reduce the height of the ensemble and thus make exiting through the door frame possible.

Finally, Figure 5 shows how the rotation combined with the movement inside the vehicle is implemented to go from the seated position inside the car to the start position for the maneuver to pass through the door.

Figure 5.Overhead view of the rotation and displacement movement to go from the wheelchair fixed position to the position for starting the maneuver to pass through the door.

CONCLUSIONS

The IBV has provided a solution for one of the key elements of the problem, through the analysis of trajectories, volumetric compatibility and the development of the necessary algorithms. The project was concluded with the installation of a prototype of the CARGO system in a Renault Clio, which can be viewed at the following link: https://www.youtube.com/watch?v=ia2mkiG9amU.

ACKNOWLEDGMENTS

This project was funded by the Seventh European Union Research and Technological Development Framework Program through contract no.(FP7-SME-2010-1-261894).