Preliminary design and development of a low-cost lower-limb exoskeleton system for paediatric rehabilitation

Abstract

In this work, the design, modeling, and development of a low-cost lower limb exoskeleton (LLES) system are presented for paediatric rehabilitation (age: 8–12 years, mass: 25–40 kg, height: 115–125 cm). The exoskeleton system, having three degrees-of-freedom (DOFs) for each limb, is designed in the SolidWorks software. A wheel support module is introduced in the design to ensure the user’s stability and safety. The finite element analysis of the hip joint connector along with the wheel support module is realized for maximum loading conditions. The holding torque capacity of exoskeleton joints is estimated using an affordable spring-based experimental setup. A working prototype of the LLES is developed with holding torque rated actuators. Thereafter, the dynamic analysis for the human-exoskeleton coupled system is carried out using the Euler-Lagrange principle and SimMechanics model. The simulation results of estimating joint actuator torques are obtained for two paraplegic subjects (Case I: 10 years age, 30 kg mass, 120 cm height and Case II: 12 years age, 40 kg mass, 125 cm height). The details of input parameters such as body mass, link lengths, joint angles, and contact forces are discussed. The simulation results of dynamic analysis have shown the potential of estimating the torques of joint actuators for the developed prototype during motion assistance and gait rehabilitation.

Robust LQR-Based Neural-Fuzzy Tracking Control for a Lower Limb Exoskeleton System with Parametric Uncertainties and External Disturbances

“…Considering the subject's physiological safety, all possible degrees of freedom should be avoided at the initial phases of rehabilitation training. Invoking the design features, authors have designed a low-cost stand-alone module-aided lower limb exoskeleton system for pediatric rehabilitation in their previous work [ 32 ]. The CAD model of the designed exoskeleton system is shown in Figures 1(a) and 1(b) .…”

“…To serve subjects of different heights, a telescopic link joint arrangement was designed around the knee joint of the exoskeleton system. Moreover, a detailed structural analysis of the stand-alone module was carried for maximum loading conditions at the hip joint [ 32 ].…”

“…where 6) stepper motor, ( 7) timing belt, ( 8) support module, ( 9) wheels, and ( 10) telescopic link joint connector) and (b) LEES with a human dummy [32].…”

“…Figure 1: CAD model of (a) LLES (labels: (1) thigh link, (2) shank link, (3) foot link, (4) hybrid stepper motor, (5) lead screw actuator, (6) stepper motor, (7) timing belt, (8) support module, (9) wheels, and (10) telescopic link joint connector) and (b) LEES with a human dummy[32].…”

Single-motor driven multi-joints lower limb exoskeleton system based on controllable clamper

“…In addition, several rigid exoskeletons have been developed. [7][8][9] The weight of these full-body rigid exoskeletons is generally relatively large, for example, the total weight of ReWalk is 20.9 kg; the knee rehabilitation device developed by the MIT Media Lab 10 is driven by tendon-sheath transmission system. The device separates the power output component and joint execution component because tendon-sheath's characteristic of flexible transmission path, so as to reduce the weight and moment of inertia of the executive component, which can prolong the life time of the device and make wearing more convenient.…”