Light-Weight Wearable Gyroscopic Actuators Can Modulate Balance Performance and Gait Characteristics: A Proof-of-Concept Study

Abstract

Falling is a major cause of morbidity, and is often caused by a decrease in postural stability. A key component of postural stability is whole-body centroidal angular momentum, which can be influenced by control moment gyroscopes. In this proof-of-concept study, we explore the influence of our wearable robotic gyroscopic actuator "GyroPack" on the balance performance and gait characteristics of non-impaired individuals (seven female/eight male, 30 ± 7 years, 68.8 ± 8.4 kg). Participants performed a series of balance and walking tasks with and without wearing the GyroPack. The device displayed various control modes, which were hypothesised to positively, negatively, or neutrally impact postural control. When configured as a damper, the GyroPack increased mediolateral standing time and walking distance, on a balance beam, and decreased trunk angular velocity variability, while walking on a treadmill. When configured as a negative damper, both peak trunk angular rate and trunk angular velocity variability increased during treadmill walking. This exploratory study shows that gyroscopic actuators can influence balance and gait kinematics. Our results mirror the findings of our earlier studies; though, with more than 50% mass reduction of the device, practical and clinical applicability now appears within reach.

Keywords: balance; control moment gyroscope; falling; postural control; walking; wearable robotics.

Figure 2

Visualisation of order of conditions applied during all balance beam tasks and treadmill walking.

Figure A1

Box plot of anteroposterior standing time for the placebo mode and for the negative, low, high, and best damper conditions. Each participant is denoted by a different symbol to allow comparison across conditions.

Figure A2

Box plot of the peak trunk angular rate for the placebo mode and for the negative, low, and high damper conditions. The asterisks denote significant differences between conditions (*—p < 0.05, **—p < 0.01). Each participant is denoted by a different symbol to allow comparison across conditions.

Figure 1

(Left): Stick-figure visualising the CMG on the back of the person, where ${\widehat{\mathit{g}}}_g$, ${\widehat{\mathit{g}}}_s$, and ${\widehat{\mathit{g}}}_t$, respectively, denote the gimbal axis, flywheel axis, and the perpendicular output axis; ${\widehat{\mathit{u}}}_u$, ${\widehat{\mathit{u}}}_v$, and ${\widehat{\mathit{u}}}_w$ denote the unit axes of the body coordinate frame; and $\mathit{\omega }$ is the trunk angular velocity vector about all three axes. (Middle): overground balance beam laboratory setup, participants walk and stand on the beam with their arms crossed. (Right): a wide treadmill, without handrails on the side, participants walk with arms crossed.

Figure 3

Box plot of performance outcomes and subjective rating during baseline and placebo conditions. The diamond marker shows the overall condition average. The black dots show the individual participant means. The asterisk denotes a significant difference between conditions (p < 0.05).

Figure 4

Box plot of distance walked on the beam for the placebo mode and for the negative, low, high, and best damper conditions. The asterisk denotes a significant difference between conditions (p < 0.05). Each participant is denoted by a different symbol to allow comparison across conditions.

Figure 5

Box plot of mediolateral standing time for the placebo mode and for the negative, low, high, and best damper conditions. The asterisk denotes a significant difference between conditions (p < 0.05). Each participant is denoted by a different symbol to allow comparison across conditions.

Figure 6

Box plot of the subjective rating of “how the condition feels compares to normal walking on the street”. Each participant is denoted by a different symbol to allow comparison across conditions. The asterisk denotes a significant difference between conditions (p < 0.05).

Figure 7

Box plot of the trunk angular velocity variability for the placebo mode and for the negative, low, and high damper conditions. Each participant is denoted by a different symbol to allow comparison across conditions. The asterisks denote significant differences between conditions (*—p < 0.05, **—p < 0.01).

Figure 8

Box plot showing the pre- and post-baseline conditions for beam walking, and mediolateral and anteroposterior balancing. The diamond marker shows the overall condition average. The black dots show the individual participant means. The asterisk denotes a significant difference between conditions (p < 0.05).