Design and Computational Modeling of a Modular, Compliant Robotic Assembly for Human Lumbar Unit and Spinal Cord Assistance

Abstract

Wearable soft robotic systems are enabling safer human-robot interaction and are proving to be instrumental for biomedical rehabilitation. In this manuscript, we propose a novel, modular, wearable robotic device for human (lumbar) spine assistance that is developed using vacuum driven, soft pneumatic actuators (V-SPA). The actuators can handle large, repetitive loads efficiently under compression. Computational models to capture the complex non-linear mechanical behavior of individual actuator modules and the integrated assistive device are developed using the finite element method (FEM). The models presented can predict system behavior at large values of mechanical deformations and allow for rapid design iterations. It is shown that a single actuator module can be used to obtain a variety of different motion and force profiles and yield multiple degrees of freedom (DOF) depending on the module loading conditions, resulting in high system versatility and adaptability, and efficient replication of the targeted motion range for the human spinal cord. The efficacy of the finite element model is first validated for a single module using experimental results that include free displacement and blocked-forces. These results are then extended to encompass an extensive investigation of bio-mechanical performance requirements from the module assembly for the human spine-assistive device proposed.

Modular Reconfigurable Robotics

“…Off-the-shelf actuators are used in a variety of MRR systems: DC motors (16,17,18,19), stepper motors (20,21), and servo motors (17,22). There are customized actuators for achieving unconventional movements such as a three-DOF pneumatic actuator (23,24) or an electromagnetic inertial actuator (25). These actuators provide mobility to an independent module or to the rest of the structure for changing the configuration (19,21,25).…”

Design and Simulation of Spine Rehabilitation Soft Robotic Actuator

“…Because of the change of the internal parameters of the rubber tube, it is necessary to consider the way of manufacture of the soft actuator. For most soft actuator, current methods of fabrication involve the casting of silicone rubbers into machined or 3D-printed [17], [18]. By comparing the properties of common soft materials such as silicone rubber, natural rubber, IPMC, hydrogel, etc., and the material parameters that have been obtained.…”

“…In order to obtain the accurate material parameters of silicone rubber, the relevant test results are given in [18], [20]. Combining formula (1) and (2), which are respectively obtained with the material coefficients as follows: C 1 = 0.34 Mpa, C 2 = 0.00 Mpa and C 1 = 0.0425 Mpa, C 2 = 0.00 Mpa for the silicone rubber.…”

A Mechatronics-Embedded Pneumatic Soft Modular Robot Powered via Single Air Tube

“…Soft modules are manufactured using soft materials, such as silica gel or rubber, which have characteristics of flexibility and continuous deformation. Therefore, many researchers have studied soft modular robots, including omnidirectional soft robots [13], rotary soft module and bending soft module [14], three types of pneumatically actuated soft modules (SoBL) [15], the soft modular robot with connecting part [16], elastomeric hollow cubes with magnetic connecting mechanisms [17], bidirectional bending modules [18], pneumatic actuators with four chambers [19], multi-spherical modular soft robots [20][21][22][23], bending-type fluidic elastomer actuators [24], modular soft robots with voice coil actuators [25], soft-bodied caterpillar-like modular robots [26], and vacuum-powered soft pneumatic actuator (V-SPA) modules [27,28].…”

“…A few researchers have investigated the gas source sharing issue. Gunjan Agarwal proposed a vacuum-powered soft pneumatic actuator (V-SPA), which shared a vacuum power supply [27,28]. However, the V-SPA has a novel solenoid valve, manufactured by piezoelectric ceramic technology, which is a non-universal technology for researchers to manufacture soft modular robots.…”