Portable haptic device for lower limb amputee gait feedback: assessing static and dynamic perceptibility

Loss of joints and severed sensory pathway cause reduced mobility capabilities in lower limb amputees. Although prosthetic devices attempt to restore normal mobility functions, lack of awareness and control of limb placement increase the risk of falling and causing amputee to have high level of visual dependency. Haptic feedback can serve as a cue for gait events during ambulation thus providing sense of awareness of the limb position. This paper presents a wireless wearable skin stretch haptic device to be fitted around the thigh region. The movement profile of the device was characterized and a preliminary work with able-bodied participants and an above-knee amputee to assess the ability of users to perceive the delivered stimuli during static and dynamic mode is reported. Perceptibility was found to be increasing with stretch magnitude. It was observed that a higher magnitude of stretch was needed for the stimuli to be accurately perceived during walking in comparison to static standing, most likely due to the intense movement of the muscle and increased motor skills demand during walking activity

Real-Time Estimation of Temporal Gait Parameters in Lower Limb Amputees using Inertial Sensors

Number of individuals undergoing lower limb amputation around the world is increasing every year due to vascular diseases or complications associated with conditions such as diabetes and trauma. Limb loss has a profound impact on individual’s physical, mental and vocational abilities, resulting in the degradation of amputees’ quality of life (QOL). Following an amputation, prescription of prosthetic devices serves as an important step in improving the amputees’ QOL. Restoring functional attributes of human gait is one of the key objectives of lower limb rehabilitation. A number of studies have been carried out to evaluate the use of wearable sensors, especially the Inertial Measurement Unit (IMU), placed at different body locations to identify gait events/phases. However, a survey of the literature indicated a lack of research in development of a real-time gait event/phase detection for lower limb amputees using a single IMU attached to the shank or the prosthetic pylon. This research presents the development and evaluation of a low-cost portable gait monitoring system which detects the temporal gait events, namely initial contact (IC), foot-flat start (FFS), heel-off (HO) and toe-off TO in real-time while performing level ground and ramp activities. Foot-switches (FSW) placed underneath the foot were used as a reference system. Evaluation of the time difference recorded between the IMU and the FSW confirmed good accuracy and precision of the proposed system. Overall results showed 100% detection of IC, FFS and TO and 98.3% detection of HO in both groups (control and amputee) across all the activities. Finally, to demonstrate its practicality, the proposed system was used to evaluate and analyse the gait asymmetry for overground and treadmill walking. Detecting the temporal gait events/phases provide useful information about clinical parameters such as stance time, swing time, gait cycle duration and gait asymmetry. The proposed system could be used as a monitoring tool to assess the progress through rehabilitation, or in the development of control systems for lower limb amputees and patients with abnormal and pathological gait