Milli Schlafly

Last Name

Schlafly

First Name

Milli

ORCID

0000-0001-7252-2527

Organisational unit

09828 - Fuge, Mark / Fuge, Mark

Show all metadata

Search Results

Publications1 - 10 of 16

Ergodic specifications for flexible swarm control: From user commands to persistent adaptation
Prabhakar, Ahalya; Abraham, Ian; Taylor, Annalisa; et al. (2020)
Robotics: Science and Systems. Online Proceedings ~ Robotics: Science and System XVI
This paper presents a formulation for swarm control and high-level task planning that is dynamically responsive to user commands and adaptable to environmental changes. We design an end-to-end pipeline from a tactile tablet interface for user commands to onboard control of robotic agents based on decentralized ergodic coverage. Our approach demonstrates reliable and dynamic control of a swarm collective through the use of ergodic specifications for planning and executing agent trajectories as well as responding to user and external inputs. We validate our approach in a virtual reality simulation environment and in real-world experiments at the DARPA OFFSET Urban Swarm Challenge FX3 field tests with a robotic swarm where user-based control of the swarm and mission-based tasks require a dynamic and flexible response to changing conditions and objectives in real-time.
3D printed passive compliant and articulating prosthetic ankle foot
Schlafly, Milli; Ramakrishnan, Tyagi; Reed, Kyle (2017)
Proceedings of the ASME 2017 International Mechanical Engineering Congress and Exposition. Volume 3: Biomedical and Biotechnology Engineering
The human ankle is crucial to mobility as it counteracts the forces and moments created during walking. Around 85% of the 1.7 million people in the United States living with limb loss are transtibial (below knee) and transfemoral (above knee) amputees who are missing their ankle and require a prosthetic. This paper presents the Compliant and Articulating Prosthetic Ankle (CAPA) foot, a solution that uses torsional springs to store and release energy at three different locations on the mechanism, assisting in forward motion. The CAPA foot utilizes 3D printing and allows for the full ankle range of motion in the sagittal plane. Testing was performed with the CAPA foot on the Computer Assisted Rehabilitation Environment on an able-bodied person wearing a prosthetic simulator. Compared to the conventional non-articulating Solid Ankle Cushioned Heel foot, the CAPA foot is shown to better mimic the ground reaction forces and ankle angles of a healthy gait.
Novel passive ankle-foot prosthesis mimics able-bodied ankle angles and ground reaction forces
Schlafly, Milli; Reed, Kyle B. (2020)
Clinical Biomechanics
Background: During gait, the human ankle both bends with ease and provides push-off forces that facilitate forward motion. The ankle is crucial for support, stabilization, and adapting to different slopes and terrains. Individuals with lower limb amputation require an ankle-foot prosthesis for basic mobility. Methods: Inspired by the role of the ankle-foot in an able-bodied gait, the 3D printed Compliant and Articulating Prosthetic Ankle (CAPA) foot was designed. It consists of four articulating components connected by torsion springs and produces forces that are dependent on the ankle angle. Using the Computer Assisted Rehabilitation Environment, able-bodied individuals walked wearing a prosthetic simulator with the Solid Ankle Cushioned Heel foot, Renegade® AT, and multiple versions of the CAPA. These versions test compliant vs. stiff, small vs. large rocker radius, and pretension vs. none. We hypothesized that the CAPA would have larger ankle range of motion, push-off forces, and braking forces. Findings: Compared to existing prostheses, the novel prosthesis exhibits greater and significantly different ankle range of motion and sagittal plane ground reaction forces than existing prostheses during gait. Nine out of ten individuals prefer the novel prosthesis to the existing prostheses, and there is a statistically significant difference in difficulty level ratings. Interpretation: By providing a personalizable and passive alternative to existing designs, the CAPA could improve the quality of life for the growing number of individuals living with limb loss in the United States and around the world.
Evaluation of 3D printed anatomically scalable transfemoral prosthetic knee
Ramakrishnan, Tyagi; Schlafly, Milli; Reed, Kyle B. (2017)
2017 International Conference on Rehabilitation Robotics (ICORR)
This case study compares a transfemoral amputee's gait while using the existing Ossur Total Knee 2000 and our novel 3D printed anatomically scalable transfemoral prosthetic knee. The anatomically scalable transfemoral prosthetic knee is 3D printed out of a carbon-fiber and nylon composite that has a gear-mesh coupling with a hard-stop weight-actuated locking mechanism aided by a cross-linked four-bar spring mechanism. This design can be scaled using anatomical dimensions of a human femur and tibia to have a unique fit for each user. The transfemoral amputee who was tested is high functioning and walked on the Computer Assisted Rehabilitation Environment (CAREN) at a self-selected pace. The motion capture and force data that was collected showed that there were distinct differences in the gait dynamics. The data was used to perform the Combined Gait Asymmetry Metric (CGAM), where the scores revealed that the overall asymmetry of the gait on the Ossur Total Knee was more asymmetric than the anatomically scalable transfemoral prosthetic knee. The anatomically scalable transfemoral prosthetic knee had higher peak knee flexion that caused a large step time asymmetry. This made walking on the anatomically scalable transfemoral prosthetic knee more strenuous due to the compensatory movements in adapting to the different dynamics. This can be overcome by tuning the cross-linked spring mechanism to emulate the dynamics of the subject better. The subject stated that the knee would be good for daily use and has the potential to be adapted as a running knee.
Shoulder abduction loading affects motor coordination in individuals with chronic stroke, informing targeted rehabilitation
Kalinowska, Aleksandra; Rudy, Kyra; Schlafly, Milli; et al. (2020)
2020 8th IEEE RAS/EMBS International Conference for Biomedical Robotics and Biomechatronics (BioRob)
Individuals post stroke experience motor impairments, such as loss of independent joint control, weakness, and delayed movement initiation, leading to an overall reduction in arm function. Their motion becomes slower and more discoordinated, making it difficult to complete timing-sensitive tasks, such as balancing a glass of water or carrying a bowl with a ball inside it. Understanding how the stroke-induced motor impairments interact with each other can help design assisted training regimens for improved recovery. In this study, we investigate the effects of abnormal joint coupling patterns induced by flexion synergy on timing-sensitive motor coordination in the paretic upper limb. We design a virtual ball-in-bowl task that requires fast movements for optimal performance and implement it on a robotic system, capable of providing varying levels of abduction loading at the shoulder. We recruit 12 participants (6 individuals with chronic stroke and 6 unimpaired controls) and assess their skill at the task at 3 levels of loading, defined by the vertical force applied at the robot end-effector. Our results show that, for individuals with stroke, loading has a significant effect on their ability to generate quick coordinated motion. With increases in loading, their overall task performance decreases and they are less able to compensate for ball dynamics-frequency analysis of their motion indicates that abduction loading weakens their ability to generate movements at the resonant frequency of the dynamic task. This effect is likely due to an increased reliance on lower resolution indirect motor pathways in individuals post stroke. Given the inter-dependency of loading and dynamic task performance, we can create targeted robot-aided training protocols focused on improving timing-sensitive motor control, similar to existing progressive loading therapies, which have shown efficacy for expanding reachable workspace post stroke.
Roll-Over Shape–Based Design of Novel Biomimetic Ankle-Foot Prosthesis
Schlafly, Milli; Reed, Kyle B. (2021)
Journal of Prosthetics and Orthotics
Introduction Past research suggests that able-bodied individuals actively control their gait kinematics to produce one invariant roll-over shape (ROS). The ROS is a spatial representation of the center of pressure in a shank-based coordinate system. Because individuals with an amputation do not have adaptive control over their center of pressure during gait, the ankle-foot prosthesis determines the resultant ROS. This study aimed to design the mechanical properties of ankle-foot prostheses to achieve specific ROSs during gait. Methods The authors developed a mathematical model that, when used in combination with ground reaction force and shank angle experimental data, predicts the ROS created by the novel Compliant and Articulating Prosthetic Ankle (CAPA) foot. The CAPA consists of four articulating components connected by torsion springs. Able-bodied individuals walked wearing a prosthetic simulator with the solid ankle cushioned heel foot, a dynamic response foot (the Renegade AT), and versions of the CAPA with distinctly different predicted ROSs. The experimental ROS of each trial was presented, and quantitative ROS characteristics were evaluated for statistical significance. Predicted and experimental shapes for each version of the CAPA were compared by computing the distance between the shapes and ROS characteristics. Finally, we evaluated whether our method predicts the same ROS regardless of the experimental data used for the prediction. Results Changes to the mechanical properties of the CAPA resulted in statistically significant differences in ROS characteristics, notably forward position, forward length, and orientation (P < 0.05). The mean distance between points on the predicted and experimental ROSs is 1.54% of the length of the CAPA. We demonstrated that experimental ROSs can be predicted using gait data from a different version of the CAPA and a different individual. Conclusions This study presents and experimentally validates a method to predict the ROSs created by eight versions of the CAPA during gait. The method enables prosthetists and researchers to design ankle-foot prostheses based on the ROS created during gait.
Feature selection in gait classification of leg length and distal mass
Schlafly, Milli; Yilmaz, Yasin; Reed, Kyle B. (2019)
Informatics in Medicine Unlocked
Technologies such as motion capture systems and force plates can aid in gait diagnosis and help identify the underlying differences between gait patterns. To support the most effective integration of these technologies in health professions, it is helpful to understand which features are most important in classification. Twenty individuals walked with combinations of an asymmetric leg length using a shoe with a small or large height and/or an asymmetric distal mass using a small or large ankle weight. These conditions changed the resultant gait of participants to impose asymmetric gait impairments. Different classifiers such as Support Vector Machines with different kernel functions were trained to classify leg length into 3 classes and distal mass into 5 classes using spatial-temporal, kinematic, and kinetic features, and evaluated for every combination of three features. Push-off force asymmetry was found to be an important feature in the classification of both leg length and distal mass. Asymmetry with regards to minimum knee angle, maximum hip extension, and the first vertical peak resulted in the best model for classifying leg length with an accuracy of 64.8%. Asymmetry with regards to braking force, push-off force, and vertical work resulted in the best model for classifying distal mass with an accuracy of 69.9%. The results suggest that the optimal features vary according to the specific impairment.
Measuring Human-Robot Team Benefits Under Time Pressure in a Virtual Reality Testbed
Popovic, Katarina; Schlafly, Milli; Prabhakar, Ahalya; et al. (2023)
2023 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS)
During a natural disaster such as hurricane, earthquake, or fire, robots have the potential to explore vast areas and provide valuable aid in search & rescue efforts. These scenarios are often high-pressure and time-critical with dynamically-changing task goals. One limitation to these large scale deployments is effective human-robot interaction. Prior work shows that collaboration between one human and one robot benefits from shared control. Here we evaluate the efficacy of shared control for human-swarm teaming in an immersive virtual reality environment. Although there are many human-swarm interaction paradigms, few are evaluated in high-pressure settings representative of their intended end use. We have developed an open-source virtual reality testbed for realistic evaluation of human-swarm teaming performance under pressure. We conduct a user study (n=16) comparing four human-swarm paradigms to a baseline condition with no robotic assistance. Shared control significantly reduces the number of instructions needed to operate the robots. While shared control leads to marginally improved team performance in experienced participants, novices perform best when the robots are fully autonomous. Our experimental results suggest that in immersive, high-pressure settings, the benefits of robotic assistance may depend on how the human and robots interact, and the human operator's expertise.
Effect of asymmetric knee height on gait asymmetry for unilateral transfemoral amputees
Ramakrishnan, Tyagi; Schlafly, Milli; Reed, Kyle B. (2017)
International Journal of Current Advanced Research
Collaborative robots can augment human cognition in regret-sensitive tasks
Schlafly, Milli; Prabhakar, Ahalya; Popovic, Katarina; et al. (2024)
PNAS Nexus
Despite theoretical benefits of collaborative robots, disappointing outcomes are well documented by clinical studies, spanning rehabilitation, prostheses, and surgery. Cognitive load theory provides a possible explanation for why humans in the real world are not realizing the benefits of collaborative robots: high cognitive loads may be impeding human performance. Measuring cognitive availability using an electrocardiogram, we ask 25 participants to complete a virtual-reality task alongside an invisible agent that determines optimal performance by iteratively updating the Bellman equation. Three robots assist by providing environmental information relevant to task performance. By enabling the robots to act more autonomously—managing more of their own behavior with fewer instructions from the human—here we show that robots can augment participants’ cognitive availability and decision-making. The way in which robots describe and achieve their objective can improve the human’s cognitive ability to reason about the task and contribute to human–robot collaboration outcomes. Augmenting human cognition provides a path to improve the efficacy of collaborative robots. By demonstrating how robots can improve human cognition, this work paves the way for improving the cognitive capabilities of first responders, manufacturing workers, surgeons, and other future users of collaborative autonomy systems.

Publications1 - 10 of 16

Milli Schlafly

Last Name

First Name

ORCID

Organisational unit

Filters

Search Results