Real-Time Identification of Knee Joint Walking Gait as Preliminary Signal for Developing Lower Limb Exoskeleton

Abstract

An exoskeleton is a device used for walking rehabilitation. In order to develop a proper rehabilitation exoskeleton, a user’s walking intention needs to be captured as the initial step of work. Moreover, every human has a unique walking gait style. This work introduced a wearable sensor, which aimed to recognize the walking gait phase, as the fundamental step before applying it into the rehabilitation exoskeleton. The sensor used in this work was the IMU sensor, used to recognize the pitch angle generated from the knee joint while the user walks, as information about the walking gait cycle, before doing the investigation on how to identify the walking gait cycle. In order to identify the walking gait cycle, Neural Network has been proposed as a method. The gait cycle identification was generated to recognize the gait cycle on the knee joint. To verify the performance of the proposed method, experiments have been done in real-time application. The experiments were carried out with different processes such as walking on a flat floor, climbing up, and walking down stairs. Five subjects were trained and tested using the system. The experiments showed that the proposed method was able to recognize each gait cycle for all users as they wore the sensor on their knee joints. This study has the potential to be applied on an exoskeleton rehabilitation robot as a further research experiment.

Review of Human-exoskeleton Control Strategy for Lower Limb Rehabilitation Exoskeleton

“…Susanto et al [34] proposed a neural network model for the recognition of knee motion cycles, which includes seven phases such as heel strike and contralateral toe off the ground, by using an IMU sensor in the middle of the thigh and thus predicting the change in angle during the wearer's knee motion. In addition, this method is capable of recognizing a variety of motion patterns such as walking up and down stairs, and walking on flat ground.…”

Hierarchical Classification of Subject-Cooperative Control Strategies for Lower Limb Exoskeletons in Gait Rehabilitation: A Systematic Review

“…These sensors are crucial in determining various gait features, such as phase, step length, cadence, etc. In particular, certain supervisory control schemes, such as Finite State Machine (FSM) with FSR [30,46,52] and IMU [28,53,64,66], utilize gait phases as additional inputs to the high-level control in combination with reference joint trajectories. For example, Chen et al [46] implemented an FSM-based supervisory control in which the FSR and encoders (velocity) were employed to discretize the gait cycle into different phases.…”

Sensors and Actuation Technologies in Exoskeletons: A Review

“…As can be seen in Figure 27 , IMU sensors are almost exclusively used for LLE; in fact, one of their main functions is to help in the complex task of studying the gait phases. Susanto et al, in [ 116 ], used an IMU sensor to recognize the pitch angle generated from the knee joint while the user of a LLE walks as useful information about the walking gait cycle. Often, multiple sensors are used together; an example is given; however, there are many works in which this has been found.…”