Haptic contact with a walking dog improves human balance during a quiet tandem task with various levels of difficulty

BACKGROUND: When a person walks a dog, information from variables of their own postural control is integrated with haptic information from the dog’s movements (e.g., direction, speed of movement, pulling forces). AIM: We examined how haptic information provided through contact with a moving endpoint (here, the leash of a dog walking on a treadmill) influenced an individual’s postural control during a quiet tandem standing task with and without restricted vision and under various elevations of the support surface (increased task difficulty levels). METHOD: Adults performed a 30-second quiet tandem stance task on a force platform while holding a leash attached to a dog who walked on a treadmill parallel to the force platform. Conditions included: haptic contact (dog and no-dog), vision constraint (eyes open, EO, and eyes closed, EC), and surfaces (4 heights). RESULTS: Interaction between haptic condition and vision showed that contact with the dog leash reduced root mean square (RMS) and mean sway speed (MSS). RMS showed that the highest surface had the greatest rate of sway reduction during haptic contact with EC, and an increase with EO. CONCLUSION: The dog’s movements were used as a haptic reference to aid balance when eyes were closed. In this condition, contact with the dog’s leash reduced the extent of sway variability on the higher surfaces.

Cooperative Ankle-Exoskeleton Control Can Reduce Effort to Recover Balance After Unexpected Disturbances During Walking

BackgroundIn the last two decades, lower-limb exoskeletons have been developed to assist human standing and locomotion. One of the ongoing challenges is the cooperation between the exoskeleton balance support and the wearer control. Here we present a cooperative ankle-exoskeleton control strategy to assist in balance recovery after unexpected disturbances during walking, which is inspired on human balance responses.MethodsWe evaluated the novel controller in ten able-bodied participants wearing the ankle modules of the Symbitron exoskeleton. During walking, participants received unexpected forward pushes with different timing and magnitude at the pelvis level, while being supported or not by the robotic assistance provided by the controller.ResultsThe results show that the controller was able to reduce participants’ effort while keeping similar ability to counteract and withstand the balance disturbances (average reduction of 10.09% in soleus activity, 5.20% in gastrocnemius medialis activity and 6.67% in gastrocnemius lateralis activity for the stance leg).ConclusionThe proposed controller was able to cooperate with the able-bodied participants in counteracting perturbations, contributing to the state-of-the-art of bio-inspired cooperative ankle exoskeleton controllers for supporting dynamic balance. In the future, this control strategy may be used in exoskeletons to support and improve balance control in users with motor disabilities.

Reproducing Human Arm Strategy and Its Contribution to Balance Recovery Through Model Predictive Control

The study of human balance recovery strategies is important for human balance rehabilitation and humanoid robot balance control. To date, many efforts have been made to improve balance during quiet standing and walking motions. Arm usage (arm strategy) has been proposed to control the balance during walking motion in the literature. However, limited research exists on the contributions of the arm strategy for balance recovery during quiet standing along with ankle and hip strategy. Therefore, in this study, we built a simplified model with arms and proposed a controller based on nonlinear model predictive control to achieve human-like balance control. Three arm states of the model, namely, active arms, passive arms, and fixed arms, were considered to discuss the contributions of arm usage to human balance recovery during quiet standing. Furthermore, various indexes such as root mean square deviation of joint angles and recovery energy consumption were verified to reveal the mechanism behind arm strategy employment. In this study, we demonstrate to computationally reproduce human-like balance recovery with and without arm rotation during quiet standing while applying different magnitudes of perturbing forces on the upper body. In addition, the conducted human balance experiments are presented as supplementary information in this paper to demonstrate the concept on a typical example of arm strategy.

A Study of Human Balance and Coordination Using a Head Mounted Display

This paper reports on an experiment in human subject balance and coordination using a HTC Vive head mounted display to create a virtual environment. For the experiment, 30 male human subjects of college age and 30 female subjects of college age were asked to navigate along a clear path in a virtual world using a controller with their dominant hand and asked to balance a virtual ball on a virtual plate using the other controller in the non-dominant hand. The test subjects moved along a clearly marked path, with three surprise obstacles occurring: a large rock landing near the path, and explosion near the path, and a flock of birds coming across the path. Data included 6 degree of freedom trajectories for the head, and both hands, as well as data gathered by the computer system on ball location and velocity, plate location and velocity and ball status. Likert scale questionnaires were answered by the test subjects relative to video game experience, sense of presence, and ease of managing the ball movement. Statistics showed that the male students dropped the ball less frequently at p = 0.0254 and p = 0.0036. In contrast, female students were aware of their performance with correlation levels of 0.632 and 0.588.

A wearable light-touch contact device for human balance support

There is an urgent need for the development of ways to address the major issue of falls among today’s globally aging population. The authors here outline a new approach referred to as virtual light-touch contact to mitigate postural sway during ambulatory and stationary periods, and propose a wearable light-touch (WLT) system featuring a virtual partition around the user that allows determination of virtual forces resulting from related contact. The data produced are used to create vibrotactile fingertip feedback, which supports comprehensive perception of the partition. Non-impaired subjects were recruited to support evaluation of the prototype system (incorporating tactile stimulation and motion-capture technology), with outcomes showing successful mitigation of postural sway in a heel-to-toe tandem stance. Research performed with 150 able-bodied volunteers to validate the performance of the new set-up (incorporating an acceleration sensor and a voice coil motor to render the light-touch effect) suggested that the proposed WLT approach supports human balance on a level comparable to that of the light-touch effect.

Measuring Vestibular Contributions to Age-Related Balance Impairment: A Review

Aging is associated with progressive declines in both the vestibular and human balance systems. While vestibular lesions certainly contribute to imbalance, the specific contributions of age-related vestibular declines to age-related balance impairment is poorly understood. This gap in knowledge results from the absence of a standardized method for measuring age-related changes to the vestibular balance pathways. The purpose of this manuscript is to provide an overview of the existing body of literature as it pertains to the methods currently used to infer vestibular contributions to age-related imbalance.