Robotic lower limb prostheses have the power to revolutionize mobility by enhancing gait efficiency and facilitating movement. While several design approaches have been explored to create lightweight and energy-efficient devices, the potential of underactuation remains largely untapped in lower limb prosthetics. Taking inspiration from the natural harmony of walking, in this article, we have developed an innovative active transfemoral prosthesis. By incorporating underactuation, our design uses a single power actuator placed near the knee joint and connected to a differential mechanism to drive both the knee and ankle joints. We conduct comprehensive benchtop tests and evaluate the prosthesis with three individuals who have above-knee amputations, assessing its performance in walking, stair climbing, and transitions between sitting and standing. Our evaluation focuses on gathering position and torque data recorded from sensors integrated into the prosthesis and comparing these measurements to biomechanical data of able-bodied locomotion. Our findings highlight the promise of underactuation in advancing lower limb prosthetics and demonstrate the feasibility of our knee–ankle underactuated design in various tasks, showcasing its ability to replicate natural movement.

To allow wheelchair (electronic or manual) users to practice driving in different safe, repeatable and controlled scenarios, the use of simulator as a training tool is considered here. In this context, the capabilities of providing high fidelity motions for users of the simulator is highlighted as one of the most important aspects for the effectiveness of the tool. For this purpose, the motion cueing algorithm (MCA) is studied in our work to regenerate wheelchair motion cues by transforming motions of the real or simulated wheelchair into the simulator motion. The studied algorithm is developed based on Model Predictive Control (MPC) approach to efficiently optimize the motions of the platform. The overall problem is formulated using mixed-integer quadratic programming (MIQP) which involves not only the vestibular model, strict constraints of the platform but also the perception threshold in the optimization cost function. In the end, the performance assessment of the system using different control techniques is analyzed, showing the effectiveness of the proposed approach in the simulation environment.

The lack of sensory feedback in lower-limb amputees is the major cause of (i) amputees difficulty to keep balance, (ii) suboptimal performance in gait functions and (iii) increased energy consumption. This also hugely affects their participation in the activities of daily living. Improving postural control functions in people with lower-limb amputation has the aim to enhance their quality of life and is achieved through the restoration of their lost sensory feedback. The objective of this paper is to propose a stimulation system for restoring plantar pressure perception and knee-joint proprioception in lower-limb amputees. The proposed approach is based on the combined use of two FSRs, two accelerometers and two or three vibrotactile actuators. For validating the system, two experimental sessions were carried out on sixteen healthy subjects and one lower-limb amputee. They were aimed to (i) assess if vibrotactile feedback can improve balance control in lower-limb amputees and (ii) investigate the potentiality of the vibrotactile perception as a means to restore amputees' knee-joint proprioception. Quantitative indices capable of describing users' performance were extracted from the processed data and a statistical analysis was performed to compare different types of sensory feedback: i.e. (i) augmented visuo-proprioceptive feedback, no feedback, forearm vibrotactile feedback and low-back vibrotactile feedback in the 1stexperimental session and (ii) forearm continuous vibrotactile feedback, low-back continuous vibrotactile feedback, forearm discrete vibrotactile feedback, and low-back discrete vibrotactile feedback in the 2ndexperimental session. The achieved results on the vibrotactile stimulation were encouraging for both applications, i.e. restoring amputees' plantar pressure perception and knee-joint proprioception.

One of the main problems in the prosthetic hand design is to provide the hand with a reliable system for force and slippage control. The real-time detection of an object slippage during grasping plays a fundamental role in performing a stable grasp. Aim of this paper is to propose and test (i) a system for object slippage detection during grasping, (ii) a control strategy for grasping force regulation and slippage prevention and (iii) a finger coordination method for replicating on the prosthesis system a human-like behaviour. The approach has been validated on a real prosthetic hand, i.e. the IH2 Azzurra (developed by Prensilia), on which tips force sensing resistors have been placed. The preliminary experimental results have demonstrated the feasibility of the methods for slipping detection and for force/slippage control and have shown that the prosthetic hand is able to perform a stable pinch grasp of different objects guaranteeing finger coordination.