@article{zhang_zhu_huang_yu_sen huang_lopez-sanchez_devine_abdelhady_zheng_bulea_et al._2024, title={Actuator optimization and deep learning-based control of pediatric knee exoskeleton for community-based mobility assistance}, volume={97}, ISSN={["0957-4158"]}, DOI={10.1016/j.mechatronics.2023.103109}, abstractNote={Lightweight and smart exoskeletons offer the potential to improve mobility in children. State-of-the-art pediatric exoskeletons are typically clinic-based since they are either tethered or portable but cumbersome and their design is often not optimized across a range of environments and users. To facilitate pediatric exoskeleton in community settings, we first proposed an actuator optimization framework that identified the optimal design parameters for both motor and transmission while minimizing the actuator mass and satisfying the output torque, speed, bandwidth, and resistance torque requirements. Guided by the optimization results, we customized a simple, lightweight actuator that met all mechatronic constraints for our portable exoskeleton (1.78 kg unilateral). Secondly, we adopted deep learning (Long Short Term Memory) based on gait phase estimation to facilitate stable control for community use. The models accurately estimated the gait phase on irregular walking patterns (accuracy 94.60%) without explicit training in children (typically developing and with cerebral palsy). The controller results demonstrated an elevated ability to adapt to the irregular gait patterns of the child with cerebral palsy. The experimental results in the child with typical development and four healthy adults demonstrated accurate assistive torque tracking performance (accuracy 97.00%) at different walking speeds (i.e., under uncertain torque to wearers). This work presented a holistic solution that includes both hardware innovation (actuator optimization framework) and software innovation (deep learning-based control) towards the paradigm shift of pediatric exoskeletons from clinic to community setting.}, journal={MECHATRONICS}, author={Zhang, Sainan and Zhu, Junxi and Huang, Tzu-Hao and Yu, Shuangyue and Sen Huang, Jin and Lopez-Sanchez, Ivan and Devine, Taylor and Abdelhady, Mohamed and Zheng, Minghui and Bulea, Thomas C. and et al.}, year={2024}, month={Feb} }
 @article{liu_liu_sajedi_su_liang_zheng_2024, title={An audio-based risky flight detection framework for quadrotors}, volume={6}, ISSN={["2631-6315"]}, DOI={10.1049/csy2.12105}, abstractNote={Abstract}, number={1}, journal={IET CYBER-SYSTEMS AND ROBOTICS}, author={Liu, Wansong and Liu, Chang and Sajedi, Seyedomid and Su, Hao and Liang, Xiao and Zheng, Minghui}, year={2024}, month={Mar} }
 @article{kruse_schur_johnson-marcus_gilbert_di lallo_gao_su_2024, title={Assistive Technology's Potential to Improve Employment of People with Disabilities}, volume={1}, ISSN={["1573-3688"]}, DOI={10.1007/s10926-023-10164-w}, journal={JOURNAL OF OCCUPATIONAL REHABILITATION}, author={Kruse, Douglas and Schur, Lisa and Johnson-Marcus, Hazel-Anne and Gilbert, Lauren and Di Lallo, Antonio and Gao, Weibo and Su, Hao}, year={2024}, month={Jan} }
 @article{xing_zhang_huang_huang_su_li_2024, title={Spatial Iterative Learning Torque Control of Robotic Exoskeletons for High Accuracy and Rapid Convergence Assistance}, volume={3}, ISSN={["1941-014X"]}, DOI={10.1109/TMECH.2024.3365045}, journal={IEEE-ASME TRANSACTIONS ON MECHATRONICS}, author={Xing, Xueyan and Zhang, Sainan and Huang, Tzuhao and Huang, Jin Sen and Su, Hao and Li, Yanan}, year={2024}, month={Mar} }
 @article{yu_yang_huang_zhu_visco_hameed_stein_zhou_su_2023, title={Artificial Neural Network-Based Activities Classification, Gait Phase Estimation, and Prediction}, volume={1}, ISSN={["1573-9686"]}, DOI={10.1007/s10439-023-03151-y}, abstractNote={Gait patterns are critical to health monitoring, gait impairment assessment, and wearable device control. Unrhythmic gait pattern detection under community-based conditions is a new frontier in this area. The present paper describes a high-accuracy gait phase estimation and prediction algorithm built on a two-stage artificial neural network. This work targets to develop an algorithm that can estimate and predict the gait cycle in real time using a portable controller with only two IMU sensors (one on each thigh) in the community setting. Our algorithm can detect the gait phase in unrhythmic conditions during walking, stair ascending, and stair descending, and classify these activities with standing. Moreover, our algorithm is able to predict both future intra- and inter-stride gait phases, offering a potential means to improve wearable device controller performance. The proposed data-driven algorithm is based on a dataset consisting of 5 able-bodied subjects and validated on 3 different able-bodied subjects. Under unrhythmic activity situations, validation shows that the algorithm can accurately identify multiple activities with 99.55% accuracy, and estimate ([Formula: see text]: 6.3%) and predict 200-ms-ahead ([Formula: see text]: 8.6%) the gait phase percentage in real time, which are on average 57.7 and 54.0% smaller than the error from the event-based method in the same conditions. This study showcases a solution to estimate and predict gait status for multiple unrhythmic activities, which may be deployed to controllers for wearable robots or health monitoring devices.}, journal={ANNALS OF BIOMEDICAL ENGINEERING}, author={Yu, Shuangyue and Yang, Jianfu and Huang, Tzu-Hao and Zhu, Junxi and Visco, Christopher J. and Hameed, Farah and Stein, Joel and Zhou, Xianlian and Su, Hao}, year={2023}, month={Jan} }
 @article{xiao_musa_godage_su_chen_2023, title={Kinematics and Stiffness Modeling of Soft Robot With a Concentric Backbone}, volume={15}, ISSN={["1942-4310"]}, DOI={10.1115/1.4055860}, abstractNote={Abstract}, number={5}, journal={JOURNAL OF MECHANISMS AND ROBOTICS-TRANSACTIONS OF THE ASME}, author={Xiao, Qingyu and Musa, Mishek and Godage, Isuru S. and Su, Hao and Chen, Yue}, year={2023}, month={Oct} }
 @article{wang_li_jian_su_wang_fang_2023, title={Modeling and control of a bedside cable-driven lower-limb rehabilitation robot for bedridden individuals}, volume={11}, ISSN={["2296-4185"]}, DOI={10.3389/fbioe.2023.1321905}, abstractNote={Individuals with acute neurological or limb-related disorders may be temporarily bedridden and unable to go to the physical therapy departments. The rehabilitation training of these patients in the ward can only be performed manually by therapists because the space in inpatient wards is limited. This paper proposes a bedside cable-driven lower-limb rehabilitation robot based on the sling exercise therapy theory. The robot can actively drive the hip and knee motions at the bedside using flexible cables linking the knee and ankle joints. A human–cable coupling controller was designed to improve the stability of the human–machine coupling system. The controller dynamically adjusts the impedance coefficient of the cable driving force based on the impedance identification of the human lower-limb joints, thus realizing the stable motion of the human body. The experiments with five participants showed that the cable-driven rehabilitation robot effectively improved the maximum flexion of the hip and knee joints, reaching 85° and 90°, respectively. The mean annulus width of the knee joint trajectory was reduced by 63.84%, and the mean oscillation of the ankle joint was decreased by 56.47%, which demonstrated that human joint impedance identification for cable-driven control can effectively stabilize the motion of the human–cable coupling system.}, journal={FRONTIERS IN BIOENGINEERING AND BIOTECHNOLOGY}, author={Wang, Daoyu and Li, Jicai and Jian, Zhuo and Su, Hao and Wang, Hongbo and Fang, Fanfu}, year={2023}, month={Nov} }
 @article{zhao_hong_li_qi_qing_su_yin_2023, title={Physically intelligent autonomous soft robotic maze escaper}, volume={9}, ISSN={["2375-2548"]}, DOI={10.1126/sciadv.adi3254}, abstractNote={Autonomous maze navigation is appealing yet challenging in soft robotics for exploring priori unknown unstructured environments, as it often requires human-like brain that integrates onboard power, sensors, and control for computational intelligence. Here, we report harnessing both geometric and materials intelligence in liquid crystal elastomer–based self-rolling robots for autonomous escaping from complex multichannel mazes without the need for human-like brain. The soft robot powered by environmental thermal energy has asymmetric geometry with hybrid twisted and helical shapes on two ends. Such geometric asymmetry enables built-in active and sustained self-turning capabilities, unlike its symmetric counterparts in either twisted or helical shapes that only demonstrate transient self-turning through untwisting. Combining self-snapping for motion reflection, it shows unique curved zigzag paths to avoid entrapment in its counterparts, which allows for successful self-escaping from various challenging mazes, including mazes on granular terrains, mazes with narrow gaps, and even mazes with in situ changing layouts.}, number={36}, journal={SCIENCE ADVANCES}, author={Zhao, Yao and Hong, Yaoye and Li, Yanbin and Qi, Fangjie and Qing, Haitao and Su, Hao and Yin, Jie}, year={2023}, month={Sep} }
 @article{luo_androwis_adamovich_nunez_su_zhou_2023, title={Robust walking control of a lower limb rehabilitation exoskeleton coupled with a musculoskeletal model via deep reinforcement learning}, volume={20}, ISSN={["1743-0003"]}, DOI={10.1186/s12984-023-01147-2}, abstractNote={Abstract}, number={1}, journal={JOURNAL OF NEUROENGINEERING AND REHABILITATION}, author={Luo, Shuzhen and Androwis, Ghaith and Adamovich, Sergei and Nunez, Erick and Su, Hao and Zhou, Xianlian}, year={2023}, month={Mar} }
 @article{normand_lee_su_sulzer_2023, title={The effect of hip exoskeleton weight on kinematics, kinetics, and electromyography during human walking}, volume={152}, ISSN={["1873-2380"]}, DOI={10.1016/j.jbiomech.2023.111552}, abstractNote={In exoskeleton research, transparency is the degree to which a device hinders the movement of the user, a critical component of performance and usability. Transparency is most often evaluated individually, thus lacking generalization. Our goal was to systematically evaluate transparency due to inertial effects on gait of a hypothetical hip exoskeleton. We predicted that the weight distribution around the pelvis and the amount of weight applied would change gait characteristics. We instructed 21 healthy individuals to walk on a treadmill while bearing weights on the pelvis between 4 and 8 kg in three different configurations, bilaterally, unilaterally (left side) and on the lumbar portion of the back (L4). We measured kinematics, kinetics, and muscle activity during randomly ordered trials of 1.5 min at typical walking speed. We also calculated the margin of stability to measure medial–lateral stability. We observed that loading the hips bilaterally with 4 kg had no changes in kinematics, kinetics, dynamic stability, or muscle activity, but above 6 kg, sagittal joint power was increased. Loading the lumbar area increased posterior pelvic tilt at 6 kg and decreased dynamic stability at 4 kg, with many individuals reporting some discomfort. For the unilateral placement, above 4 kg dynamic stability was decreased and hip joint power was increased, and above 6 kg the pelvis begins to dip towards the loaded side. These results show the different effects of weight distribution around the pelvis. This study represents a novel, systematic approach to characterizing transparency in exoskeleton design (clinicaltrials.gov: NCT05120115).}, journal={JOURNAL OF BIOMECHANICS}, author={Normand, Michael A. and Lee, Jeonghwan and Su, Hao and Sulzer, James S.}, year={2023}, month={May} }
 @article{chen_liu_su_liang_zheng_2022, title={A hybrid disturbance observer for delivery drone?s oscillation suppression}, volume={88}, ISSN={["0957-4158"]}, DOI={10.1016/j.mechatronics.2022.102907}, abstractNote={This paper proposes a new hybrid disturbance observer (DOB) to help suppress disturbance to the control systems. The proposed hybrid DOB consists of three main parts: (1) an actual system, (2) a simulated system, and (3) a learning filter that connects the actual and simulated systems. The simulated system aims to replicate the actual system response, where it leverages a neural network model to predict the input disturbance and generate the predicted system response. Such system response is used to generate a learning signal through a learning filter; this learning signal is then added to the feedforward loop of the estimation framework to enhance the disturbance estimate and its suppression performance for the actual system. The proposed hybrid DOB is designed to advance the standard DOB structure with a learning-based feedforward compensation. While the proposed method does not modify the baseline controller, it is well suited to systems whose baseline controllers are difficult or impossible to be changed. Considering the delivery drones are subject to oscillations when dropping payloads, experimental tests with multiple payload dropping scenarios have been conducted using both the hybrid and standard DOB, where the compared results validate the effectiveness and advantages of the proposed hybrid DOB.}, journal={MECHATRONICS}, author={Chen, Zhu and Liu, Chang and Su, Hao and Liang, Xiao and Zheng, Minghui}, year={2022}, month={Dec} }
 @article{buckner_miikkulainen_forrest_milano_zou_prunk_irrgang_cohen_su_murphy_et al._2022, title={AI reflections in 2021}, volume={1}, ISSN={["2522-5839"]}, DOI={10.1038/s42256-021-00435-7}, abstractNote={For a third year in a row, we followed up with authors of several recent Comments and Perspectives in Nature Machine Intelligence about what happened after their article was published: how did the topic they wrote about develop, did they gain new insights, and what are their hopes and expectations for AI in 2022?}, journal={NATURE MACHINE INTELLIGENCE}, author={Buckner, Cameron and Miikkulainen, Risto and Forrest, Stephanie and Milano, Silvia and Zou, James and Prunk, Carina and Irrgang, Christopher and Cohen, I. Glenn and Su, Hao and Murphy, Robin R. and et al.}, year={2022}, month={Jan} }
 @article{gonzalez_su_fu_2022, title={Age-Dependent Upper Limb Myoelectric Control Capability in Typically Developing Children}, volume={30}, ISSN={["1558-0210"]}, DOI={10.1109/TNSRE.2022.3166800}, abstractNote={Research in EMG-based control of prostheses has mainly utilized adult subjects who have fully developed neuromuscular control. Little is known about children’s ability to generate consistent EMG signals necessary to control artificial limbs with multiple degrees of freedom. As a first step to address this gap, experiments were designed to validate and benchmark two experimental protocols that quantify the ability to coordinate forearm muscle contractions in typically developing children. Non-disabled, healthy adults and children participated in our experiments that aimed to measure an individual’s ability to use myoelectric control interfaces. In the first experiment, participants performed 8 repetitions of 16 different hand/wrist movements. Using offline classification analysis based on Support Vector Machine, we quantified their ability to consistently produce distinguishable muscle contraction patterns. We demonstrated that children had a smaller number of highly independent movements (can be classified with >90% accuracy) than adults did. The second experiment measured participants’ ability to control the position of a cursor on a 1-DoF virtual slide using proportional EMG control with three different visuomotor gain levels. We found that children had higher failure rates and slower average target acquisitions than adults did, primarily due to longer correction times that did not improve over repetitive practice. We also found that the performance in both experiments was age-dependent in children. The results of this study provide novel insights into the technical and empirical basis to better understand neuromuscular development in children with upper-limb loss.}, journal={IEEE TRANSACTIONS ON NEURAL SYSTEMS AND REHABILITATION ENGINEERING}, author={Gonzalez, Miguel and Su, Hao and Fu, Qiushi}, year={2022}, pages={1009–1018} }
 @article{yu_huang_di lallo_zhang_wang_fu_su_2022, title={Bio-inspired design of a self-aligning, lightweight, and highly-compliant cable-driven knee exoskeleton}, volume={16}, ISSN={["1662-5161"]}, DOI={10.3389/fnhum.2022.1018160}, abstractNote={Powered knee exoskeletons have shown potential for mobility restoration and power augmentation. However, the benefits of exoskeletons are partially offset by some design challenges that still limit their positive effects on people. Among them, joint misalignment is a critical aspect mostly because the human knee joint movement is not a fixed-axis rotation. In addition, remarkable mass and stiffness are also limitations. Aiming to minimize joint misalignment, this paper proposes a bio-inspired knee exoskeleton with a joint design that mimics the human knee joint. Moreover, to accomplish a lightweight and high compliance design, a high stiffness cable-tension amplification mechanism is leveraged. Simulation results indicate our design can reduce 49.3 and 71.9% maximum total misalignment for walking and deep squatting activities, respectively. Experiments indicate that the exoskeleton has high compliance (0.4 and 0.1 Nm backdrive torque under unpowered and zero-torque modes, respectively), high control bandwidth (44 Hz), and high control accuracy (1.1 Nm root mean square tracking error, corresponding to 7.3% of the peak torque). This work demonstrates performance improvement compared with state-of-the-art exoskeletons.}, journal={FRONTIERS IN HUMAN NEUROSCIENCE}, author={Yu, Shuangyue and Huang, Tzu-Hao and Di Lallo, Antonio and Zhang, Sainan and Wang, Tian and Fu, Qiushi and Su, Hao}, year={2022}, month={Nov} }
 @article{zhu_jiao_dominguez_yu_su_2022, title={Design and Backdrivability Modeling of a Portable High Torque Robotic Knee Prosthesis With Intrinsic Compliance for Agile Activities}, volume={6}, ISSN={["1941-014X"]}, url={http://dx.doi.org/10.1109/tmech.2022.3176255}, DOI={10.1109/TMECH.2022.3176255}, abstractNote={High-performance prostheses are crucial to enable versatile activities like walking, squatting, and running for lower extremity amputees. State-of-the-art prostheses are either not powerful enough to support demanding activities or have low compliance (low backdrivability) due to the use of high speed ratio transmission. Besides speed ratio, gearbox design is also crucial to the compliance of wearable robots, but its role is typically ignored in the design process. This article proposed an analytical backdrive torque model that accurately estimates the backdrive torque from both motor and transmission to inform the robot design. Following this model, this article also proposed methods for gear transmission design to improve compliance by reducing inertia of the knee prosthesis. We developed a knee prosthesis using a high torque actuator (built-in 9:1 planetary gear) with a customized 4:1 low-inertia planetary gearbox. Benchtop experiments show the backdrive torque model is accurate and proposed prosthesis can produce 200 Nm high peak torque (shield temperature <60 °C), high compliance (2.6 Nm backdrive torque), and high control accuracy (2.7/8.1/1.7 Nm RMS tracking errors for 1.25 m/s walking, 2 m/s running, and 0.25 Hz squatting, that are 5.4%/4.1%/1.4% of desired peak torques). Three able-bodied subject experiments showed our prosthesis could support agile and high-demanding activities.}, journal={IEEE-ASME TRANSACTIONS ON MECHATRONICS}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Zhu, Junxi and Jiao, Chunhai and Dominguez, Israel and Yu, Shuangyue and Su, Hao}, year={2022}, month={Jun} }
 @article{chen_li_su_zhang_yu_2022, title={Design of a Bio-Inspired Gait Phase Decoder Based on Temporal Convolution Network Architecture With Contralateral Surface Electromyography Toward Hip Prosthesis Control}, volume={16}, ISSN={["1662-5218"]}, DOI={10.3389/fnbot.2022.791169}, abstractNote={Inter-leg coordination is of great importance to guarantee the safety of the prostheses wearers, especially for the subjects at high amputation levels. The mainstream of current controllers for lower-limb prostheses is based on the next motion state estimation by the past motion signals at the prosthetic side, which lacks immediate responses and increases falling risks. A bio-inspired gait pattern generation architecture was proposed to provide a possible solution to the bilateral coordination issue. The artificial movement pattern generator (MPG) based on the temporal convolution network, fusing with the motion intention decoded from the surface electromyography (sEMG) measured at the impaired leg and the motion status from the kinematic modality of the prosthetic leg, can predict four sub gait phases. Experiment results suggested that the gait phase decoder exhibited a relatively high intra-subject consistency in the gait phase inference, adapted to various walking speeds with mean decoding accuracy ranging from 89.27 to 91.16% across subjects, and achieved an accuracy of 90.30% in estimating the gait phase of the prosthetic leg in the hip disarticulation amputee at the self-selected pace. With the proof of concept and the offline experiment results, the proposed architecture improves the walking coordination with prostheses for the amputees at hip level amputation.}, journal={FRONTIERS IN NEUROROBOTICS}, author={Chen, Yixi and Li, Xinwei and Su, Hao and Zhang, Dingguo and Yu, Hongliu}, year={2022}, month={May} }
 @article{bulea_sharma_sikdar_su_2022, title={Editorial: Next Generation User-Adaptive Wearable Robots}, volume={9}, ISSN={["2296-9144"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85133809356&partnerID=MN8TOARS}, DOI={10.3389/frobt.2022.920655}, abstractNote={One study presents a pediatric exoskeleton that provides adaptive assistance to knee extension to alleviate crouch and its evaluation in a child with cerebral palsy (Chen et al.). Two manuscripts present novel controllers which leverage reinforcement learning and their evaluation in simulation: one for assisting squatting motion (Luo et al.) and one for bipedal exoskeleton walking in three dimensions (Liu et al.). The fi nal manuscript evaluates the fusion of surface electromyography (EMG) and muscle sonography to estimate limb movement in a variety of locomotor tasks (Rabe and Fey). a novel Motor Assisted Hybrid Neuroprosthesis (MAHNP) with actuated hip and knee joints and a distributed control architecture that integrates the exoskeleton with customized FES systems. A supervisory gait event detector split the gait cycle into four discrete states. The hip and/or knee motors could be activated with bursts of torque to assist the stimulation-driven limb motion. The system was evaluated in two participants with SCI, each with different implanted stimulation systems. Each}, journal={FRONTIERS IN ROBOTICS AND AI}, author={Bulea, Thomas C. and Sharma, Nitin and Sikdar, Siddhartha and Su, Hao}, year={2022}, month={Jun} }
 @article{afzal_zhu_tseng_lincoln_francisco_su_chang_2022, title={Evaluation of Muscle Synergy During Exoskeleton-Assisted Walking in Persons With Multiple Sclerosis}, volume={69}, ISSN={["1558-2531"]}, DOI={10.1109/TBME.2022.3166705}, abstractNote={Objective: Gait deficit after multiple sclerosis (MS) can be characterized by altered muscle activation patterns. There is preliminary evidence of improved walking with a lower limb exoskeleton in persons with MS. However, the effects of exoskeleton-assisted walking on neuromuscular modifications are relatively unclear. The objective of this study was to investigate the muscle synergies, their activation patterns and the differences in neural strategies during walking with (EXO) and without (No-EXO) an exoskeleton. Methods: Ten subjects with MS performed walking during EXO and No-EXO conditions. Electromyography signals from seven leg muscles were recorded. Muscle synergies and the activation profiles were extracted using non-negative matrix factorization. Results: The stance phase duration was significantly shorter during EXO compared to the No-EXO condition (p<0.05). Moreover, typically 3-5 modules were extracted in each condition. The module-1 (comprising Vastus Medialis and Rectus Femoris muscles), module-2 (comprising Soleus and Medial Gastrocnemius muscles), module-3 (Tibialis Anterior muscle) and module-4 (comprising Biceps Femoris and Semitendinosus muscles) were comparable between conditions. During EXO condition, Semitendinosus and Vastus Medialis emerged in module-5 in 7/10 subjects. Compared to No-EXO, average activation amplitude was significantly reduced corresponding to module-2 during the stance phase and module-3 during the swing phase during EXO. Conclusion: Exoskeleton-assistance does not alter the existing synergy modules, but could induce a new module to emerge, and alters the control of these modules, i.e., modifies the neural commands indicated by the reduced amplitude of the activation profiles. Significance: The work provides insights on the potential underlying mechanism of improving gait functions after exoskeleton-assisted locomotor training.}, number={10}, journal={IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING}, author={Afzal, Taimoor and Zhu, Fangshi and Tseng, Shih-Chiao and Lincoln, John A. and Francisco, Gerard E. and Su, Hao and Chang, Shuo-Hsiu}, year={2022}, month={Oct}, pages={3265–3274} }
 @article{chang_tseng_su_francisco_2022, title={How can wearable robotic and sensor technology advance neurorehabilitation?}, volume={16}, ISSN={["1662-5218"]}, DOI={10.3389/fnbot.2022.1033516}, abstractNote={COPYRIGHT © 2022 Chang, Tseng, Su and Francisco. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms. Editorial: How can wearable robotic and sensor technology advance neurorehabilitation?}, journal={FRONTIERS IN NEUROROBOTICS}, author={Chang, Shuo-Hsiu and Tseng, Shih-Chiao and Su, Hao and Francisco, Gerard E.}, year={2022}, month={Oct} }
 @article{huang_zhang_yu_maclean_zhu_di lallo_jiao_bulea_zheng_su_2022, title={Modeling and Stiffness-Based Continuous Torque Control of Lightweight Quasi-Direct-Drive Knee Exoskeletons for Versatile Walking Assistance}, volume={38}, ISSN={["1941-0468"]}, DOI={10.1109/TRO.2022.3170287}, abstractNote={State-of-the-art exoskeletons are typically limited by the low control bandwidth and small-range stiffness of actuators, which are based on high gear ratios and elastic components (e.g., series elastic actuators). Furthermore, most exoskeletons are based on discrete gait phase detection and/or discrete stiffness control, resulting in discontinuous torque profiles. To fill these two gaps, we developed a portable, lightweight knee exoskeleton using quasi-direct-drive (QDD) actuation that provides 14 N·m torque (36.8% biological joint moment for overground walking). This article presents 1) stiffness modeling of torque-controlled QDD exoskeletons and 2) stiffness-based continuous torque controller that estimates knee joint moment in real-time. Experimental tests found that the exoskeleton had a high bandwidth of stiffness control (16 Hz under 100 N·m/rad) and high torque tracking accuracy with 0.34 N·m root mean square error (6.22%) across 0–350 N·m/rad large-range stiffness. The continuous controller was able to estimate knee moments accurately and smoothly for three walking speeds and their transitions. Experimental results with eight able-bodied subjects demonstrated that our exoskeleton was able to reduce the muscle activities of all eight measured knee and ankle muscles by 8.60%–15.22% relative to the unpowered condition and two knee flexors and one ankle plantar flexor by 1.92%–10.24% relative to the baseline (no exoskeleton) condition.}, number={3}, journal={IEEE TRANSACTIONS ON ROBOTICS}, author={Huang, Tzu-Hao and Zhang, Sainan and Yu, Shuangyue and MacLean, Mhairi K. and Zhu, Junxi and Di Lallo, Antonio and Jiao, Chunhai and Bulea, Thomas C. and Zheng, Minghui and Su, Hao}, year={2022}, month={Jun}, pages={1442–1459} }
 @article{zhao_hong_qi_chi_su_yin_2022, title={Self-Sustained Snapping Drives Autonomous Dancing and Motion in Free-Standing Wavy Rings}, volume={12}, ISSN={["1521-4095"]}, DOI={10.1002/adma.202207372}, abstractNote={Abstract}, journal={ADVANCED MATERIALS}, author={Zhao, Yao and Hong, Yaoye and Qi, Fangjie and Chi, Yinding and Su, Hao and Yin, Jie}, year={2022}, month={Dec} }
 @article{su_kwok_cleary_iordachita_cavusoglu_desai_fischer_2022, title={State of the Art and Future Opportunities in MRI-Guided Robot-Assisted Surgery and Interventions}, volume={5}, ISSN={["1558-2256"]}, DOI={10.1109/JPROC.2022.3169146}, abstractNote={Magnetic resonance imaging (MRI) can provide high-quality 3-D visualization of target anatomy, surrounding tissue, and instrumentation, but there are significant challenges in harnessing it for effectively guiding interventional procedures. Challenges include the strong static magnetic field, rapidly switching magnetic field gradients, high-power radio frequency pulses, sensitivity to electrical noise, and constrained space to operate within the bore of the scanner. MRI has a number of advantages over other medical imaging modalities, including no ionizing radiation, excellent soft-tissue contrast that allows for visualization of tumors and other features that are not readily visible by other modalities, true 3-D imaging capabilities, including the ability to image arbitrary scan plane geometry or perform volumetric imaging, and capability for multimodality sensing, including diffusion, dynamic contrast, blood flow, blood oxygenation, temperature, and tracking of biomarkers. The use of robotic assistants within the MRI bore, alongside the patient during imaging, enables intraoperative MR imaging (iMRI) to guide a surgical intervention in a closed-loop fashion that can include tracking of tissue deformation and target motion, localization of instrumentation, and monitoring of therapy delivery. With the ever-expanding clinical use of MRI, MRI-compatible robotic systems have been heralded as a new approach to assist interventional procedures to allow physicians to treat patients more accurately and effectively. Deploying robotic systems inside the bore synergizes the visual capability of MRI and the manipulation capability of robotic assistance, resulting in a closed-loop surgery architecture. This article details the challenges and history of robotic systems intended to operate in an MRI environment and outlines promising clinical applications and associated state-of-the-art MRI-compatible robotic systems and technology for making this possible.}, journal={PROCEEDINGS OF THE IEEE}, author={Su, Hao and Kwok, Ka-Wai and Cleary, Kevin and Iordachita, Iulian and Cavusoglu, M. Cenk and Desai, Jaydev P. and Fischer, Gregory S.}, year={2022}, month={May} }
 @article{li_he_deng_chen_wang_fan_su_yu_2021, title={A Center of Mass Estimation and Control Strategy for Body-Weight-Support Treadmill Training}, volume={29}, ISSN={["1558-0210"]}, DOI={10.1109/TNSRE.2021.3126104}, abstractNote={Walking disorders are common in post-stroke. Body weight support (BWS) systems have been proposed and proven to enhance gait training systems for recovering in individuals with hemiplegia. However, the fixed weight support and walking speed increase the risk of falling and decrease the active participation of the subjects. This paper proposes a strategy to enhance the efficiency of BWS treadmill training. It consists in regulating the height of the BWS system to track the height of the subject’s center of mass (CoM), whereby the CoM is estimated through a long-short term memory (LSTM) network and a locomotion recognition system. The LSTM network takes the walking speed, body-height to leg-length ratio, hip and knee joint angles of the hemiplegic subjects’ non-paretic side from the locomotion recognition system as input signals and outputs the CoM height to a BWS treadmill training robot. Besides, the hip and knee joints’ ranges of motion are increased by 34.54% and 25.64% under the CoM height regulation compared to the constant weight support, respectively. With the CoM height regulation strategy, the stance phase duration of the paretic side is significantly increased by 14.6% of the gait cycle, and the symmetry of the gait is also promoted. The CoM height kinematics by adjustment strategy is in good agreement with the mean values of the 14 non-disabled subjects, which demonstrated that the adjustment strategy improves the stability of CoM height during the training.}, journal={IEEE TRANSACTIONS ON NEURAL SYSTEMS AND REHABILITATION ENGINEERING}, author={Li, Xinwei and He, Bingze and Deng, Zhipeng and Chen, Yixi and Wang, Duojin and Fan, Yuanjie and Su, Hao and Yu, Hongliu}, year={2021}, pages={2388–2398} }
 @article{chen_stevenson_yu_mioskowska_yi_su_trkov_2021, title={Wearable Knee Assistive Devices for Kneeling Tasks in Construction}, volume={26}, ISSN={["1941-014X"]}, DOI={10.1109/TMECH.2021.3081367}, abstractNote={Construction workers regularly perform tasks that require kneeling, crawling, and squatting. Working in awkward kneeling postures for prolonged time periods can lead to knee pain, injuries, and osteoarthritis. In this article, we present lightweight, wearable sensing, and knee assistive devices for construction workers during kneeling and squatting tasks. Analysis of kneeling on level and sloped surfaces (0<inline-formula><tex-math notation="LaTeX">$^\circ$</tex-math></inline-formula>, 10<inline-formula><tex-math notation="LaTeX">$^\circ$</tex-math></inline-formula>, and 20<inline-formula><tex-math notation="LaTeX">$^\circ$</tex-math></inline-formula>) is performed for single- and double-leg kneeling tasks. Measurements from the integrated inertial measurement units are used for real-time gait detection and lower limb pose estimation. Detected gait events and pose estimation are used to control the assistive knee joint torque provided by lightweight exoskeletons with powerful quasi-direct drive actuation. Human subject experiments are conducted to validate the effectiveness of the proposed analysis and control design. The results show reduction in knee extension/flexion muscle activation (up to 39%) during stand-to-kneel and kneel-to-stand tasks. Knee-ground contact forces/pressures are also reduced (up to 15%) under robotic assistance during single-leg kneeling. Increasing assistive knee torque shows redistribution of the subject's weight from the knee in contact with the ground to both supporting feet. The proposed system provides an enabling intervention to potentially reduce musculoskeletal injury risks of construction workers.}, number={4}, journal={IEEE-ASME TRANSACTIONS ON MECHATRONICS}, author={Chen, Siyu and Stevenson, Duncan T. and Yu, Shuangyue and Mioskowska, Monika and Yi, Jingang and Su, Hao and Trkov, Mitja}, year={2021}, month={Aug}, pages={1989–1996} }
 @article{tang_chi_sun_huang_maghsoudi_spence_zhao_su_yin_2020, title={Leveraging elastic instabilities for amplified performance: Spine-inspired high-speed and high-force soft robots}, volume={6}, ISSN={["2375-2548"]}, url={https://publons.com/wos-op/publon/37034085/}, DOI={10.1126/SCIADV.AAZ6912}, abstractNote={Bistable spined soft robots enable high-speed cheetah-like galloping and fast-speed swimming, as well as high-force manipulation.}, number={19}, journal={SCIENCE ADVANCES}, author={Tang, Yichao and Chi, Yinding and Sun, Jiefeng and Huang, Tzu-Hao and Maghsoudi, Omid H. and Spence, Andrew and Zhao, Jianguo and Su, Hao and Yin, Jie}, year={2020}, month={May} }
 @article{comfort-centered design of a lightweight and backdrivable knee exoskeleton_2018, journal={IEEE Robotics and Automation Letters (RA-L)}, year={2018} }
 @article{su_iordorchita_tokuda_hata_liu_fischer_2017, title={Fiber Optic Force Sensors for MRI-Guided Interventions and Rehabilitation}, journal={IEEE Sensors Journal}, author={Su, H. and Iordorchita, I. and Tokuda, J. and Hata, N. and Liu, X. and Fischer, G.S.}, year={2017} }
 @article{su_shang_li_fischer_2017, title={MRI-Guided Telesurgery System Using a Fabry-Perot Interferometry Force Sensor and a Pneumatic Haptic Device}, journal={Annals of Biomedical Engineering}, author={Su, H. and Shang, W. and Li, G. and Fischer, G.S.}, year={2017} }
 @article{su_li_rucker_webster_fischer_2016, title={A Concentric Tube Continuum Robot with Piezoelectric Actuation for MRI-Guided Closed-Loop Targeting}, journal={Annals of Biomedical Engineering}, author={Su, H. and Li, G. and Rucker, D.C. and Webster, R.J., III and Fischer, G.S.}, year={2016} }
 @article{piezoelectrically actuated robotic system for mri-guided prostate percutaneous therapy_2015, url={https://publons.com/wos-op/publon/37144096/}, DOI={10.1109/TMECH.2014.2359413}, abstractNote={This paper presents a fully actuated robotic system for percutaneous prostate therapy under continuously acquired live magnetic resonance imaging (MRI) guidance. The system is composed of modular hardware and software to support the surgical workflow of intraoperative MRI-guided surgical procedures. We present the development of a 6-degree-of-freedom (DOF) needle placement robot for transperineal prostate interventions. The robot consists of a 3-DOF needle driver module and a 3-DOF Cartesian motion module. The needle driver provides needle cannula translation and rotation (2-DOF) and stylet translation (1-DOF). A custom robot controller consisting of multiple piezoelectric motor drivers provides precision closed-loop control of piezoelectric motors and enables simultaneous robot motion and MR imaging. The developed modular robot control interface software performs image-based registration, kinematics calculation, and exchanges robot commands and coordinates between the navigation software and the robot controller with a new implementation of the open network communication protocol OpenIGTLink. Comprehensive compatibility of the robot is evaluated inside a 3-T MRI scanner using standard imaging sequences and the signal-to-noise ratio loss is limited to 15%. The image deterioration due to the present and motion of robot demonstrates unobservable image interference. Twenty-five targeted needle placements inside gelatin phantoms utilizing an 18-gauge ceramic needle demonstrated 0.87-mm root-mean-square (RMS) error in 3-D Euclidean distance based on MRI volume segmentation of the image-guided robotic needle placement procedure.}, journal={IEEE/ASME Transactions on Mechatronics}, year={2015} }
 @article{su_shang_cole_li_harrington_camilo_tokuda_tempany_hata_fischer_2015, title={Robotic System for MRI-Guided Stereotactic Neurosurgery}, journal={IEEE/ASME Transactions on Mechatronics}, author={Su, H. and Shang, W. and Cole, G. and Li, G. and Harrington, K. and Camilo, A. and Tokuda, J. and Tempany, C.M. and Hata, N. and Fischer, G.S.}, year={2015} }
 @inproceedings{a mri-guided concentric tube continuum robot with piezoelectric actuation: a feasibility study_2012, url={https://publons.com/wos-op/publon/19604815/}, DOI={10.1109/ICRA.2012.6224550}, abstractNote={This paper presents a versatile magnetic resonance imaging (MRI) compatible concentric tube continuum robotic system. The system enables MR image-guided placement of a curved, steerable active cannula. It is suitable for a variety of clinical applications including image-guided neurosurgery and percutaneous interventions, along with procedures that involve accessing a desired image target, through a curved trajectory. This 6 degree-of-freedom (DOF) robotic device is piezoelectrically actuated to provide precision motion with joint-level precision of better than 0.03mm, and is fully MRI-compatible allowing simultaneous robotic motion and imaging with no image quality degradation. The MRI compatibility of the robot has been evaluated under 3 Tesla MRI using standard prostate imaging sequences, with an average signal to noise ratio loss of less than 2% during actuator motion. The accuracy of active cannula control was evaluated in benchtop trials using an external optical tracking system with RMS error in tip placement of 1.00mm. Preliminary phantom trials of three active cannula placements in the MRI scanner showed cannula trajectories that agree with our kinematic model, with a RMS tip placement error of 0.61 - 2.24 mm.}, booktitle={IEEE International Conference on Robotics and Automation}, year={2012} }
 @inproceedings{an affordable compact humanoid robot for autism spectrum disorder interventions in children_2011, url={https://publons.com/wos-op/publon/4427059/}, DOI={10.1109/IEMBS.2011.6091316}, abstractNote={Autism Spectrum Disorder impacts an ever-increasing number of children. The disorder is marked by social functioning that is characterized by impairment in the use of nonverbal behaviors, failure to develop appropriate peer relationships and lack of social and emotional exchanges. Providing early intervention through the modality of play therapy has been effective in improving behavioral and social outcomes for children with autism. Interacting with humanoid robots that provide simple emotional response and interaction has been shown to improve the communication skills of autistic children. In particular, early intervention and continuous care provide significantly better outcomes. Currently, there are no robots capable of meeting these requirements that are both low-cost and available to families of autistic children for in-home use. This paper proposes the piloting the use of robotics as an improved diagnostic and early intervention tool for autistic children that is affordable, non-threatening, durable, and capable of interacting with an autistic child. This robot has the ability to track the child with its 3 degree of freedom (DOF) eyes and 3-DOF head, open and close its 1-DOF beak and 1-DOF each eyelids, raise its 1-DOF each wings, play sound, and record sound. These attributes will give it the ability to be used for the diagnosis and treatment of autism. As part of this project, the robot and the electronic and control software have been developed, and integrating semi-autonomous interaction, teleoperation from a remote healthcare provider and initiating trials with children in a local clinic are in progress.}, booktitle={Annual International Conference of the IEEE Engineering in Medicine and Biology}, year={2011} }
 @inproceedings{real-time mri-guided needle placement robot with integrated fiber optic force sensing_2011, url={https://publons.com/wos-op/publon/19604808/}, DOI={10.1109/ICRA.2011.5979539}, abstractNote={This paper presents the first prototype of a magnetic resonance imaging (MRI) compatible piezoelectric actuated robot integrated with a high-resolution fiber optic sensor for prostate brachytherapy with real-time in situ needle steering capability in 3T MRI. The 6-degrees-of-freedom (DOF) robot consists of a modular 3-DOF needle driver with fiducial tracking frame and a 3-DOF actuated Cartesian stage. The needle driver provides needle cannula rotation and translation (2-DOF) and stylet translation (1-DOF). The driver mimics the manual physician gesture by two point grasping. To render proprioception associated with prostate interventions, a Fabry-Perot interferometer based fiber optic strain sensor is designed to provide high-resolution axial needle insertion force measurement and is robust to large range of temperature variation. The paper explains the robot mechanism, controller design, optical modeling and opto-mechanical design of the force sensor. MRI compatibility of the robot is evaluated under 3T MRI using standard prostate imaging sequences and average signal noise ratio (SNR) loss is limited to 2% during actuator motion. A dynamic needle insertion is performed and bevel tip needle steering capability is demonstrated under continuous real-time MRI guidance, both with no visually identifiable interference during robot motion. Fiber optic sensor calibration validates the theoretical modeling with satisfactory sensing range and resolution for prostate intervention.}, booktitle={IEEE International Conference on Robotics and Automation}, year={2011} }