Measurement of interaction forces distributed across the attachment interface in wearable devices is critical for understanding ergonomic physical human–robot interaction (pHRI). The main challenges in sensorization of pHRI interfaces are (i) capturing the fine nature of force transmission from compliant human tissue onto rigid surfaces in the wearable device and (ii) utilizing a low-cost and easily implementable design that can be adapted for a variety of human interfaces. This paper addresses both challenges and presents a modular sensing panel that uses force-sensing resistors (FSRs) combined with robust electrical and mechanical integration principles that result in a reliable solution for distributed load measurement. The design is demonstrated through an upper-arm cuff, which uses 24 sensing panels, in conjunction with the Harmony exoskeleton. Validation of the design with controlled loading of the sensorized cuff proves the viability of FSRs in an interface sensing solution. Preliminary experiments with a human subject highlight the value of distributed interface force measurement in recognizing the factors that influence ergonomic pHRI and elucidating their effects. The modular design and low cost of the sensing panel lend themselves to extension of this approach for studying ergonomics in a variety of wearable applications with the goal of achieving safe, comfortable, and effective human–robot interaction.

Holistic consideration of the human and the robot is necessary to overcome hurdles in human-robot interaction.

Hemiparetic gait is abnormal asymmetric walking, often observed among patients with cerebral palsy or stroke. One of the major features of asymmetric gait is excessive reliance on the healthy leg, which results in improper load shift, slow walking speed, higher metabolic cost, and weakness of the unused leg. Hence, clinically it is desirable to promote gait symmetry to improve walking. While there are no clear methods to achieve this goal, we are exploring new methods where we guide the pelvis to change the gait symmetry. This controller is designed to mimic the hands of a physical therapist holding the pelvis and guiding it to promote the usage of both legs during walking. In this paper, we show that the essence of this method can be demonstrated by promoting asymmetry in the gait of healthy subjects when walking with the device. The results showed that their kinematics and kinetics changed asymmetrically during the intervention. Subjects demonstrated asymmetric lateral ground reaction force to compensate for the lateral forces applied on the pelvis. Muscle activities increased on the targeted leg show the forced use of the leg which can be used for rehabilitation of patients with an asymmetric gait.

Humans learn complex motor skills with practice and training. Though the learning process is not fully understood, several theories from motor learning, neuroscience, education, and game design suggest that curriculum-based training may be the key to efficient skill acquisition. However, designing such a curriculum and understanding its effects on learning are challenging problems. In this paper, we define the Human-skill Curriculum Markov Decision Process (H-CMDP) to systematize the design of training protocols. We also identify a vocabulary of performance features to enable the approximation for a human’s skill level across a variety of cognitive and motor tasks. A novel task domain is introduced as a testbed to evaluate the effectiveness of our approach. Human subject experiments show that (1) participants can learn to improve their performance in tasks within this domain, (2) the learning is quantifiable via our performance features, and (3) the domain is flexible enough to create distinct levels of difficulty. The long-term goal of this work is to systematize the process of curriculum-based training toward the design of protocols for robot-mediated rehabilitation.

Deploying machine vision for wearable robot control faces challenges in terms of usability, reliability, privacy, and costs.

In a previous study, a Tethered Pelvic Assist Device (TPAD) was used to successfully retrain crouch gait of children with Cerebral Palsy by applying a downward force on the pelvis during walking on a treadmill. While the results of this study were promising, an important issue was to translate this training to the children in a more practical manner. This motivated the question in this paper if a different intervention could result in similar improvements in the gait as seen with the TPAD. This is the motivation for the present study which compares the biomechanical differences in walking under two conditions: (i) the TPAD applies a pure downward force on the pelvis using tethers, and (ii) a weighted pelvic belt is used to apply the same downward force on the pelvis. In the second case, the weight belt also increases the mass at the pelvis. Ten healthy subjects performed two separate experiments while walking on an instrumented treadmill. The whole-body kinematics was recorded using a motion capture system and the ground reaction forces were measured by force plates embedded in the treadmill. We found no significant differences in the kinematic gait parameters of healthy subjects when the downwards force, equivalent to 15% body weight, applied by the TPAD was replaced by a weighted pelvic belt, with 15% body weight. However, the activation of the gastrocnemius muscle and the estimated maximum ankle torque, predicted by an inverted pendulum mathematical model, during the single support phase of walking, showed a higher increase with the weight belt when compared to a pure downward force. Thus, the weight belt, due to its simplicity, must be further considered as a more convenient candidate to translate the results of TPAD in children with cerebral palsy who suffer from