A novel methodological approach for inducing slips, trips and pelvic pulls during treadmill walking

Falls are a leading cause of injury among elderly individuals and those with walking disabilities, making fall prevention a critical public health concern. Perturbation-based balance training (PBT) has shown promise in improving balance recovery after fall-threatening events, but its effectiveness is often limited by poor transferability to diverse real-world scenarios. To address this, various training paradigms are needed to develop reactive balance responses that can effectively handle different fall-inducing situations, such as trips, slips, and bumps. This study investigates the feasibility of using the PACE-R (Passive Active CablE Robot) system, a modular, cable-based robotic module, to emulate multiple balance perturbation modalities, including slips, trips, and bumps (pelvis pulls), during treadmill walking. The PACE-R system operates through a cable mechanism that is mechanically coupled with the motor only when force application is required. When no intervention is needed, the cable is passively decoupled from the motor, maintaining minimal tension passively via a low-stiffness tension spring, ensuring high transparency and allowing for natural movement. Kinematic data, including joint angles, center of pressure (COP), and ground reaction forces (GRF), were collected during various experimental conditions to assess the system's ability to replicate realistic fall-inducing perturbations. The results of a case study indicated that each perturbation type induced distinct kinematic and kinetic responses, closely aligning with existing literature. These findings suggest that the PACE-R module, capable of simulating a range of perturbations, could replace multiple training devices, improving the accessibility of PBT and potentially reducing fall rates in individuals with balance impairments, including the elderly.Clinical relevance- The PACE-R module provides a novel, safe, and user-friendly method for the perturbation-based training, enabling diverse perturbation modalities such as trips, slips, and center-of-mass perturbations.