A pediatric robotic thumb exoskeleton for at-home rehabilitation: The Isolated Orthosis for Thumb Actuation (IOTA)

Abstract

In this paper, we present the design of a thumb exoskeleton for pediatric at-home rehabilitation. Pediatric disorders, such as cerebral palsy (CP) and stroke, can result in thumb in palm deformity greatly limiting hand function. This not only limits children's ability to perform activities of daily living but also limits important motor skill development. Specifically, the device, dubbed IOTA (Isolated Orthosis for Thumb Actuation) is a 2-DOF thumb exoskeleton that can actuate the carpometacarpal (CMC) and metacarpalphalangeal (MCP) joints through ranges of motion required for activities of daily living. The device consists of a lightweight hand-mounted mechanism that can be custom secured and aligned to the wearer. The mechanism is actuated via flexible cables that connect to a portable control box. Embedded encoders and bend sensors monitor the two degrees of freedom of the thumb and flexion/extension of the wrist. Using this platform, a number of control modes can be implemented that will enable the device to be intuitively controlled by a patient to assist with opposition grasp, fine motor control, and ultimately facilitate motor recovery. We envision this at-home device augmenting the current in-clinic therapy and enabling tele-rehabilitation where a clinician can remotely monitor a patient's usage and performance.

A fabric-regulated soft robotic glove with user intent detection using EMG and RFID for hand assistive application

“…The total weight of the device is approximately 170g, which is much smaller than the typical design requirement of 450g for any device on the hand [27]. Additionally, as the actuators work under air pressure, inflation of the actuators does not add significant amount of extra weight to the hand.…”

A Powered Finger–Thumb Wearable Hand Exoskeleton With Self-Aligning Joint Axes

“…Regarding the weight, it is hard to find comparison in the state of the art, some numbers are given in Table I. As general indication, Aubin et al determined that a device deployed on the hand should not exceed 0.5 kg [43], which is compatible with the weight of the wearable modules of HX. Next development of the design will also consider optimization of structural material distribution.…”

Design Requirements of Generic Hand Exoskeletons and Survey of Hand Exoskeletons for Rehabilitation, Assistive, or Haptic Use

“…Alternatively, an exoskeleton can align mechanical and finger joints through adjusted mechanical connections and links [15], [22], [27]- [30], [32], [33], [37], [40], [45], [52], [57], [60], [62], [63], [67], [73], [77], [84], [87]. The user wears the device before operation and a technician fixes a sliderscrew system for fitting.…”

“…Dorsal devices consist of mechanical or transmission components placed on top of the finger phalanges (Figure 8(c)) [15], [22], [23], [25]- [35], [37]- [41], [44]- [62], [64], [66]- [76], [78]- [84], [87]. Doing so, the collision between multiple finger components can be minimized while user's palm is free for future interactions with real objects.…”

“…Servo motors can be defined as rotational DC motors with a limited workspace [22], [34], [51], [68], [71]. They are fast, and can achieve high output torque and accurate position control; but require a special driving circuit for control and have higher cost compared to DC motors.…”