During the project the ESRs implement a neuro-musculoskeletal (NMS) model of the missing limb, which provides a representation of the equivalent missing muscle and bone structures that are now replaced by prosthetic devices. The model was used as a baseline to implement control strategies for balance and walking using a powered ankle prosthetic foot as well as providing feedback back to the amputee. Importantly, the project also worked on exploring novel ways to assess biomechanical performance as well as cognitive effort of amputees when using a prosthetic device (Fig. 1). All these elements were tested with healthy subjects as well as amputees, showing the feasibility of the concept.
Specifically, a model of muscle synergies capable of generating synthetic EMGs was developed. These synthetic EMGs were used as an input to the NMS model to generate torque output for the prosthetic device as a feedforward control strategy. In addition, an EMG-driven musculoskeletal control was implemented, to allow amputees to volitionally control a prosthetic device directly using their remaining muscles. Furthermore, a model of spinal reflexes was implemented. This model is used to estimate muscle activations by modelling the feedback control strategy that the central nervous system employs to modulate muscle activation in response to environmental conditions and stimuli. This model is used as an input to the NMS model, which generates the torques that the prosthetic device should apply to recover from perturbations. The results were presented and demonstrated in multiple international conferences.
A sensory feedback platform was implemented using vibrotactile and electrotactile actuators. The platform is being used to close the loop between the prosthetic device and the amputee. The feedback platform can convey the information obtained from the sensors of a prosthetic device as well as from the implemented NMS model, which enables more flexibility to find meaningful feedback parameters to improve balance and walking. The results were published in the Journal of Neuroengineering and Rehabilitation as well as multiple international conferences.
Finally, two different methods to assess the use of mechatronic lower limb prosthetic devices were implemented. An experimental study and data analysis to understand the potential of using the internal sensors of mechatronic devices as sources for gait assessment. If possible, this would allow researchers and clinicians to assess the impact of the prosthetic device on the amputee gait without the need for specialized and rather expensive equipment as well as gathering data in the real environment (out of the lab). The results were published in the Journal of Clinical Biomechanics as well as several international conferences. Furthermore, different tools to assess the cognitive attention when walking with mechatronic devices were explored. Several tests investigating the use of mobile eye trackers to measure cognitive load were completed and the results were presented in several international conferences.
A joint IP on the concept of SimBionics, under the title: Method for controlling an orthopedic device and orthopedic device. The patent is now published with numbers: WO2022017583A1, EP4185245A1 and US2023255802A1.
