Development of user-customized functional logic in microprocessor-controlled prosthetic joints

Since their release on the market in 1997, electronically controlled knee prostheses have established themselves as the leading device for improving the quality of life of transfemoral amputees. These game-changing prostheses are highly innovative compared to simply mechanical devices, as they make real-time adjustments in response to users’ gaits, providing enhanced stability and adaptability during various activities. The prosthesis and orthosis company Ottobock is present on the market with different types of electronic knee prostheses: the leading ones being the C-leg and the Genium. These models aren’t limited to providing a Basic Mode, designed for walking and simple daily activities, but they offer additional configurations called MyModes. Each MyMode represents an alternative configuration of the electronic knee compared to the Basic one, as it modifies the damping within the microprocessor-controlled hydraulic system, thereby optimising the required movements. These functionalities allow users to perform activities that require a different knee setting, particularly sports and recreational activities, without the need for alternative prosthetic devices. Moreover, the mode can be easily activated via the app connected to the prosthesis. This thesis work was carried out as part of a six-month research project at Ottobock's Research Department in Vienna, with the aim of improving the current MyModes. The goal was to enable users to configure new MyModes independently, avoiding the need for specialised technicians. The interface development process was preceded by a survey conducted through an online questionnaire filled out by 247 users and oral interviews with 10 users of different European nationalities. The survey made it possible to identify requested improvements and customisation of the existing modes and to collect feedback on autonomous programming by the users. The interface was developed using a visual programming approach, proposing puzzle blocks that encapsulate the main functionalities that can be implemented in the knee prosthesis. By combining these blocks, the customised special mode desired by the user can be created, and imported into the microprocessor that controls the knee. Although the proposed interface is not yet available as a smartphone or tablet app, during the thesis project, each block presented to the user as a puzzle piece was translated and standardised into the programming language of the State Machine that rules over the prosthesis. Thanks to this process, the combination of the individual pieces can be quickly implemented in the device, allowing the user to test what was previously programmed on paper in a short time. Thus, it simulates what will be available in the future as an interface that not only integrates the visual programming unit but also directly imports it into the prosthesis. After testing the programming interface with 10 people, focusing the 'Scooter' and 'Nordic Walking', MyModes were successfully programmed and tested by two users, demonstrating the considerable potential of the project and the importance of future investment. The possibility to configure and activate the different functionalities independently represents a significant step forward in rehabilitation and in facilitating the social reintegration of users.