@proceedings {1587049, title = {Variability Analysis of Walking with Continuously Increasing Assistance from a Soft Exosuit.}, journal = {The 1st Human Movement Variability Conference}, year = {2016}, author = {Philippe Malcolm and Denise M. Rossi and Christopher J. Siviy and Quinlivan, Brendan T. and Lee, Sangjun and Martin Grimmer and Walsh, Conor J.} } @proceedings {1139471, title = {Effect of Timing of Hip Extension Assistance with IMU-based Iterative Control during Loaded Walking with a Soft Exosuit}, journal = {Dynamic Walking}, year = {2016}, address = {Holly, Michigan, USA}, author = {Ye Ding and Panizzolo, Fausto A. and Galiana, I. and Christopher Siviy and Kenneth G. Holt and Walsh, Conor J.} } @proceedings {1075286, title = {Using Analytical Modeling to Design Customized Fiber-Reinforced Soft Actuators}, journal = { Society of Engineering Science 53rd Annual Technical Meeting}, year = {2016}, address = {University of Maryland, MD, USA, 2-5 October}, author = {Connolly, Fionnuala and Walsh, Conor J. and Bertoldi, Katia} } @proceedings {1038281, title = {A Quasi-Passive Knee Exoskeleton to Assist During Descent}, journal = {International Symposium on Wearable Robotics (WeRob) 2016}, year = {2016}, address = {La Granja, Spain}, author = {Emily Rogers and Panagiotis Polygerinos and Stephen Allen and Panizzolo, Fausto A. and Walsh, Conor J. and Holland, D{\'o}nal P.} } @article {975276, title = {Effect of timing of hip extension assistance during loaded walking with a soft exosuit}, journal = {Journal of NeuroEngineering and Rehabilitation}, volume = {2016}, number = {13}, year = {2016}, month = {3 Oct, 2016}, pages = {87}, abstract = {\ BackgroundRecent advances in wearable robotic devices have demonstrated the ability to reduce the metabolic cost of walking by assisting the ankle joint. To achieve greater gains in the future it will be important to determine optimal actuation parameters and explore the effect of assisting other joints. The aim of the present work is to investigate how the timing of hip extension assistance affects the positive mechanical power delivered by an exosuit and its effect on biological joint power and metabolic cost during loaded walking. In this study, we evaluated 4 different hip assistive profiles with different actuation timings: early-start-early-peak (ESEP), early-start-late-peak (ESLP), late-start-early-peak (LSEP), late-start-late-peak (LSLP).MethodsEight healthy participants walked on a treadmill at a constant speed of 1.5 m {\textperiodcentered} s-1 while carrying a 23 kg backpack load. We tested five different conditions: four with the assistive profiles described above and one unpowered condition where no assistance was provided. We evaluated participants{\textquoteright} lower limb kinetics, kinematics, metabolic cost and muscle activation.ResultsThe variation of timing in the hip extension assistance resulted in a different amount of mechanical power delivered to the wearer across conditions; with the ESLP condition providing a significantly higher amount of positive mechanical power (0.219 {\textpm} 0.006 W {\textperiodcentered} kg-1) with respect to the other powered conditions. Biological joint power was significantly reduced at the hip (ESEP and ESLP) and at the knee (ESEP, ESLP and LSEP) with respect to the unpowered condition. Further, all assistive profiles significantly reduced the metabolic cost of walking compared to the unpowered condition by 5.7 {\textpm} 1.5 \%, 8.5 {\textpm} 0.9 \%, 6.3 {\textpm} 1.4 \% and 7.1 {\textpm} 1.9 \% (mean {\textpm} SE for ESEP, ESLP, LSEP, LSLP, respectively).ConclusionsThe highest positive mechanical power delivered by the soft exosuit was reported in the ESLP condition, which showed also a significant reduction in both biological hip and knee joint power. Further, the ESLP condition had the highest average metabolic reduction among the powered conditions. Future work on autonomous hip exoskeletons may incorporate these considerations when designing effective control strategies.\ }, url = {http://dx.doi.org/10.1186/s12984-016-0196-8}, author = {Ye Ding and Panizzolo, Fausto A. and Christopher Siviy and Philippe Malcolm and Ignacio Galiana and Kenneth G. Holt and Conor J Walsh} } @magazinearticle {973636, title = {The 2015 Soft Robotics Competition}, journal = {IEEE Robotics \& Automation Magazine}, volume = {23}, number = {3}, year = {2016}, month = {13 Sept 2016}, pages = {25-27}, url = {http://dx.doi.org/10.1109/MRA.2016.2587959}, author = {Holland, D{\'o}nal P. and Gareth J. Bennett and George M. Whitesides and Wood, Robert J. and Walsh, Conor J.} } @proceedings {973586, title = {Autonomous Soft Exosuit for Hip Extension Assistance}, journal = {International Symposium on Wearable Robotics (WeRob) 2016}, year = {2016}, month = {18-21 October}, address = {La Granja, Spain}, author = {Nikolaos Karavas and Jinsoo Kim and Ignacio B. Galiana and Ye Ding and Couture, Adam P and Diana Wagner and Eckert-Erdheim, Asa and Conor J Walsh} } @proceedings {973596, title = {Biomechanical analysis and inertial sensing of ankle joint while stepping on an unanticipated bump}, journal = {International Symposium on Wearable Robotics (WeRob) 2016}, year = {2016}, month = {18-21 October}, address = {La Granja, Spain}, author = {Taira Miyatake and Lee, Sangjun and Ignacio B. Galiana and Rossi, Denise Martineli and Christopher Siviy and Fausto Panizzolo and Walsh, Conor J.} } @proceedings {973591, title = {Comparison of Ankle Moment Inspired And Ankle Positive Power Inspired Controllers for a Multi-articular Soft Exosuit for Walking Assistance}, journal = {International Symposium on Wearable Robotics (WeRob) 2016}, year = {2016}, month = {18-21 October}, address = {La Granja, Spain}, author = {Martin Grimmer and Lee, Sangjun and Brendan Quinlivan and Philippe Malcolm and Rossi, Denise Martineli and Christopher Siviy and Walsh, Conor J.} } @proceedings {973601, title = {Evaluation of Force Tracking Controller with Soft Exosuit for Hip Extension Assistance}, journal = {International Symposium on Wearable Robotics (WeRob) 2016}, year = {2016}, month = {18-21 October}, address = {La Granja, Spain}, author = {Su, Hao and Ye Ding and Jozefien Speeckaert and Nikolaos Karavas and Philippe Malcolm and Christopher Siviy and Conor J Walsh} } @conference {973616, title = {Fabrication of Stretchable Composites with Anisotropic Electrical Conductivity for Compliant Pressure Transducers}, booktitle = {IEEE Sensors Conference 2016}, year = {2016}, month = {31 Oct}, address = {Orlando, Florida}, abstract = {We present a simple fabrication approach for anisotropically conductive stretchable composites, towards novel flexible pressure transducers. Flexible electronic systems have gained great interest in recent years, and within this space, anisotropic conducting materials have been explored for enhanced sensing performance. However, current methods for producing these materials are complex or are limited to small fabrication areas. Our method uses film applicator coating to render commercially available conductive RTVs anisotropically conductive. A ratio of in-plane surface resistance to through-thickness resistance of 1010 was achieved using our method. Furthermore, we show that when a normal pressure is applied to such films, the in-plane resistance can be reduced by seven orders of magnitude for an applied pressure of 10 kPa. Hence these materials show great promise for the development of novel, robust pressure transducers.}, url = {dx.doi.org/10.1109/ICSENS.2016.7808424}, author = {Oluwaseun Araromi and Walsh, Conor J. and Wood, Robert J.} } @article {Gafford201678, title = {Machine learning approaches to environmental disturbance rejection in multi-axis optoelectronic force sensors}, journal = {Sensors and Actuators A: Physical}, volume = {248}, year = {2016}, month = {20 July}, pages = {78 - 87}, abstract = {Light-Intensity Modulated (LIM) force sensors are seeing increasing interest in the field of surgical robotics and flexible systems in particular. However, such sensing modalities are notoriously susceptible to ambient effects such as temperature and environmental irradiance which can register as false force readings. We explore machine learning techniques to dynamically compensate for environmental biases that plague multi-axis optoelectronic force sensors. In this work, we fabricate a multisensor: three-axis LIM force sensor with integrated temperature and ambient irradiance sensing manufactured via a monolithic, origami-inspired fabrication process called printed-circuit MEMS. We explore machine learning regression techniques to compensate for temperature and ambient light sensitivity using on-board environmental sensor data. We compare batch-based ridge regression, kernelized regression and support vector techniques to baseline ordinary least-squares estimates to show that on-board environmental monitoring can substantially improve sensor force tracking performance and output stability under variable lighting and large (\>100C) thermal gradients. By augmenting the least-squares estimate with nonlinear functions describing both environmental disturbances and cross-axis coupling effects, we can reduce the error in Fx, Fy and Fz by 10\%, 33\%, and 73\%, respectively. We assess viability of each algorithm tested in terms of both prediction accuracy and computational overhead, and analyze kernel-based regression for prediction in the context of online force feedback and haptics applications in surgical robotics. Finally, we suggest future work for fast approximation and prediction using stochastic, sparse kernel techniques.}, keywords = {Nonlinear regression}, issn = {0924-4247}, doi = {http://dx.doi.org/10.1016/j.sna.2016.06.036}, url = {http://dx.doi.org/10.1016/j.sna.2016.06.036}, author = {Joshua B. Gafford and Doshi-Velez, Finale and Wood, Robert J. and Conor J Walsh} } @proceedings {973611, title = {A soft pop-up proprioceptive actuator for minimally invasive surgery}, journal = {The 9th Hamlyn Symposium on Medical Robotics}, year = {2016}, month = {27 June}, pages = {[Best Poster Award]}, address = {London, England}, author = {Sheila Russo and Ranzani, Tommaso and Conor J Walsh and Wood, Robert J.} } @proceedings {973606, title = {A soft suction-based end effector for endoluminal tissue manipulation}, journal = {The 9th Hamlyn Symposium on Medical Robotics}, year = {2016}, month = {27 June}, address = {London, England}, author = {Ranzani, Tommaso and Sheila Russo and Conor J Walsh and Wood, Robert J.} } @proceedings {dw2016lee, title = {Lower limb biomechanical analysis of unanticipated step on a bump}, journal = {Dynamic Walking}, year = {2016}, month = {4-7 June 2016}, address = {Holly, Michigan, USA}, author = {Lee, Sangjun and Fausto Panizzolo and Taira Miyatake and Rossi, Denise Martineli and Christopher Siviy and Walsh, Conor J.} } @proceedings {dw2016bae, title = {Assisting paretic ankle motion with a soft exosuit can reduce whole-body compensatory gait patterns and improve walking efficiency for patients after stroke}, journal = {Dynamic Walking}, year = {2016}, month = {4-7 June 2016}, address = {Holly, Michigan, USA}, author = {Jaehyun Bae and Louis N. Awad and Kathleen O{\textquoteright}Donnell and Kathryn L. Hendron and Stephen Allen and De Rossi, Stefano M.M. and Kenneth G. Holt and Terry D. Ellis and Walsh, Conor J.} } @article {703236, title = {A biologically-inspired multi-joint soft exosuit that can reduce the energy cost of loaded walking}, journal = {Journal of NeuroEngineering and Rehabilitation}, volume = {13}, number = {1}, year = {2016}, month = {12 May 2016}, pages = {1-14}, abstract = { Carrying load alters normal walking, imposes additional stress to the musculoskeletal system, and results in an increase in energy consumption and a consequent earlier onset of fatigue. This phenomenon is largely due to increased work requirements in lower extremity joints, in turn requiring higher muscle activation. The aim of this work was to assess the biomechanical and physiological effects of a multi-joint soft exosuit that applies assistive torques to the biological hip and ankle joints during loaded walking. }, url = {http://dx.doi.org/10.1186/s12984-016-0150-9}, author = {Panizzolo, Fausto A. and Ignacio B. Galiana and Alan T. Asbeck and Christopher Siviy and Kai Schmidt and Kenneth G. Holt and Walsh, Conor J.} } @article {Cezar09022016, title = {Biologic-free mechanically induced muscle regeneration}, journal = {Proceedings of the National Academy of Sciences (PNAS)}, volume = {113}, number = {6}, year = {2016}, month = {9 Feb 2016}, pages = {1534-1539}, abstract = { Severe skeletal muscle injuries are common and can lead to extensive fibrosis, scarring, and loss of function. Clinically, no therapeutic intervention exists that allows for a full functional restoration. As a result, both drug and cellular therapies are being widely investigated for treatment of muscle injury. Because muscle is known to respond to mechanical loading, we investigated instead whether a material system capable of massage-like compressions could promote regeneration. Magnetic actuation of biphasic ferrogel scaffolds implanted at the site of muscle injury resulted in uniform cyclic compressions that led to reduced fibrous capsule formation around the implant, as well as reduced fibrosis and inflammation in the injured muscle. In contrast, no significant effect of ferrogel actuation on muscle vascularization or perfusion was found. Strikingly, ferrogel-driven mechanical compressions led to enhanced muscle regeneration and a \~{}threefold increase in maximum contractile force of the treated muscle at 2 wk compared with no-treatment controls. Although this study focuses on the repair of severely injured skeletal muscle, magnetically stimulated bioagent-free ferrogels may find broad utility in the field of regenerative medicine. }, doi = {10.1073/pnas.1517517113}, url = {http://dx.doi.org/10.1073/pnas.1517517113 }, author = {Cezar, Christine A. and Roche, Ellen T. and Vandenburgh, Herman H. and Duda, Georg N. and Walsh, Conor J. and Mooney, David J.} } @conference {123, title = {Controlling Negative and Positive Power at the Ankle with a Soft Exosuit}, booktitle = {IEEE International Conference on Robotics and Automation (ICRA)}, year = {2016}, month = {16-21 May 2016}, pages = {3509-3515}, address = {Stockholm, Sweden}, abstract = {The soft exosuit is a new approach for applying assistive forces over the wearer{\textquoteright}s body through load paths configured by the textile architecture. In this paper, we present a body-worn lower-extremity soft exosuit and a new control approach that can independently control the level of assistance that is provided during negative- and positive-power periods at the ankle. The exosuit was designed to create load paths assisting ankle plantarflexion and hip flexion, and the actuation system transmits forces from the motors to the suit via Bowden cables. A load cell and two gyro sensors per leg are used to measure real-time data, and the controller performs position control of the cable on a step-by-step basis with respect to the power delivered to the wearer{\textquoteright}s ankle by controlling two force parameters, the pretension and the active force. Human subjects testing results demonstrate that the controller is capable of modulating the amount of power delivered to the ankle joint. Also, significant reductions in metabolic rate (11\%-15\%) were observed, which indicates the potential of the proposed control approach to provide benefit to the wearer during walking.}, url = {http://dx.doi.org/10.1109/ICRA.2016.7487531}, author = {Lee, Sangjun and Simona Crea and Philippe Malcolm and Ignacio B. Galiana and Alan T. Asbeck and Walsh, Conor J.} } @proceedings {dw2016quinlivan, title = {Multi-articular soft exosuit continually reduces the metabolic cost of unloaded walking with increased assistance magnitude}, journal = {Dynamic Walking}, year = {2016}, month = {4-7 June 2016}, address = {Holly, Michigan, USA}, author = {Brendan Quinlivan and Lee, Sangjun and Philippe Malcolm and Rossi, Denise Martineli and Martin Grimmer and Christopher Siviy and Walsh, Conor J.} } @proceedings {dw2016siviy, title = {Optimization of soft exosuit peak force with ramp and step sweep protocol}, journal = {Dynamic Walking}, year = {2016}, month = {4-7 June 2016}, address = {Holly, Michigan, USA}, author = {Christopher Siviy and Rossi, Denise Martineli and Philippe Malcolm and Brendan Quinlivan and Lee, Sangjun and Martin Grimmer and Walsh, Conor J.} } @article {703136, title = {Self-Assembling, Low-Cost, and Modular mm-Scale Force Sensor}, journal = {IEEE Sensors Journal}, volume = {16}, number = {1}, year = {2016}, month = {1 Jan 2016}, pages = {69-76. [Cover Article]}, abstract = {The innovation in surgical robotics has seen a shift toward flexible systems that can access remote locations inside the body. However, a general reliance on the conventional fabrication techniques ultimately limits the complexity and the sophistication of the distal implementations of such systems, and poses a barrier to further innovation and widespread adoption. In this paper, we present a novel, self-assembling force sensor manufactured using a composite lamination fabrication process, wherein linkages pre-machined in the laminate provide the required degrees-of-freedom and fold patterns to facilitate self-assembly. Using the purely 2-D fabrication techniques, the energy contained within a planar elastic biasing element directly integrated into the laminate is released post-fabrication, allowing the sensor to self-assemble into its final 3-D shape. The sensors are batch-fabricated, further driving down the production costs. The transduction mechanism relies on the principle of light intensity modulation, which allows the sensor to detect axial forces with millinewton-level resolution. The geometry of the sensor was selected based on the size constraints inherent in minimally invasive surgery, as well as with a specific focus on optimizing the sensor{\textquoteright}s linearity. The sensor is unique from the fiber-based force sensors in that the emitter and the detector are encapsulated within the sensor itself. The bare sensor operates over a force range of 0-200 mN, with a sensitivity of 5 V/N and a resolution of 0.8 mN. The experimental results show that the sensor{\textquoteright}s stiffness can be tuned using a thicker material for the spring layer and/or encapsulation/integration with soft materials. The empirical validation shows that the sensor has the sensitivity and the resolution necessary to discern the biologically relevant forces in a simulated cannulation task.}, url = {http://dx.doi.org/10.1109/JSEN.2015.2476368}, author = {Joshua B. Gafford and Wood, Robert J. and Conor J Walsh} } @article {703131, title = {Sensory Enhancing Insoles Modify Gait during Inclined Treadmill Walking with Load}, journal = {Medicine \& Science in Sports \& Exercise}, volume = {48}, number = {5}, year = {2016}, month = {May 2016}, pages = {860-868}, abstract = {Introduction: Inclined walking while carrying a loaded backpack induces fatigue, which may destabilize gait and lead to injury. Stochastic resonance (SR) technology has been used to stabilize spatiotemporal gait characteristics of elderly individuals but has not been tested on healthy recreational athletes. Herein, we determined if sustained vigorous walking on an inclined surface while carrying a load destabilizes gait and if SR has a further effect. Methods: Participants were fitted with a backpack weighing 30\% of their body weight and asked to walk at a constant self-selected pace while their feet were tracked using an optical motion capture system. Their shoes were fitted with SR insoles that were set at 90\% of the participant{\textquoteright}s sensory threshold. The treadmill incline was increased every 5 min until volitional exhaustion after which the treadmill was returned to a level grade. SR stimulation was turned ON and OFF in a pairwise random fashion throughout the protocol. Spatiotemporal gait characteristics were calculated when SR was ON and OFF for the BASELINE period, the MAX perceived exertion period, and the POST period. Results: Vigorous activity increases variability in the rhythmic stepping (stride time and stride length) and balance control (double support time and stride width) mechanisms of gait. Overall, SR increased stride width variability by 9\% before, during, and after a fatiguing exercise. Conclusion: The increased stride time and stride length variability may compromise the stability of gait during and after vigorous walking. However, participants may compensate by increasing double support time and stride width variability to maintain their stability under these adverse conditions. Furthermore, applying SR resulted in an additional increase of stride width variability and may potentially improve balance before, during, and after adverse walking conditions.}, url = {http://dx.doi.org/10.1249/MSS.0000000000000831}, author = {Miranda, Daniel L. and Wen-Hao Hsu and Kelsey Petersen and Fitzgibbons, Stacey and Niemi, James and Lesniewski-Laas, Nicholas and Conor J Walsh} } @conference {703231, title = {Snap-On Robotic Wrist Module for Enhanced Dexterity in Endoscopy}, booktitle = {IEEE International Conference on Robotics and Automation (ICRA)}, year = {2016}, month = {16-21 May 2016}, pages = {4398-4405}, address = {Stockholm, Sweden}, abstract = {Burgeoning transendoscopic procedures, such as endoscopic submucosal dissection (ESD), provide a promising means of treating early-stage gastric neoplasia in a minimally-invasive way. However, the remote locations of these lesions, coupled with their origination in the submucosal layers of the gastrointestinal tract, often lead to extreme technical, cognitive and ergonomic challenges which combat the widespread applicability and adoption of these techniques. Among these challenges is achieving the in vivo dexterity required to retract and dissect tissue. By leveraging workspace and force data obtained through clinical studies, we developed a modular, disposable, distally-mounted actuator (an {\textquoteright}active endcap{\textquoteright}) that can augment an endoscopist{\textquoteright}s distal dexterity in ways that are not achievable with the endoscope{\textquoteright}s built-in degrees-of-freedom. The device consists of a flexible articulating {\textquoteright}exoskeleton{\textquoteright} manufactured via printed-circuit MEMS (PCMEMS) which engages and deflects electrosurgical tools that are passed through the endoscopic working channel. Embedded proprioceptive sensing is implemented on-board using distributed LED/phototransistor pairs and the principle of light intensity modulation (LIM). The distal degree-of-freedom is actuated using shape memory alloy (SMA) technology, and the actuation transmission system is fully contained within a 1-inch-long end cap that can be mounted on the distal end of the endoscope, thereby obviating the need for a mechanical connection to a proximal source. Proof-of-concept tests demonstrate that the actuator adds over 50 degrees of distal articulation to existing tools and can generate 450 mN of lateral force which has been clinically determined to be sufficient for performing circumferential incisions in ESD.}, url = {http://doi.org/10.1109/ICRA.2016.7487639}, author = {Joshua B. Gafford and Sheila Russo and Ranzani, Tommaso and Wood, Robert J. and Walsh, Conor J.} } @proceedings {703206, title = {A soft exosuit for assisting poststroke walking}, journal = {9th World Congress of Neurorehabilitation}, year = {2016}, month = {10-13 May 2016}, address = {Philadelphia, PA, USA}, author = {Louis N. Awad and Jaehyun Bae and Kathleen O{\textquoteright}Donnell and De Rossi, Stefano M.M. and Kathryn L. Hendron and Kenneth G. Holt and Terry D. Ellis and Conor J Walsh} } @conference {703211, title = {Soft pop-up mechanisms for micro surgical tools: design and characterization of compliant millimeter-scale articulated structures}, booktitle = {IEEE International Conference on Robotics and Automation (ICRA)}, year = {2016}, month = {16-21 May 2016}, pages = {750-757}, address = {Stockholm, Sweden}, abstract = {This paper introduces a manufacturing technique which enables the integration of soft materials and soft fluidic micro-actuators in the Pop-up book MEMS paradigm. Such a technique represents a promising approach to the design and fabrication of low cost and scalable articulated mechanisms provided with sensing capabilities and on-board actuation with potential applications in the field of minimally invasive surgery. Design and integration of soft components in the rigid-flex laminates is described along with the resulting soft pop-up mechanisms realized at different scales. Prototype characterization is presented, demonstrating forces and dexterity in a range suitable for surgical applications, as well as the possibility to integrate sensing capabilities. Based on these results, a multi-articulated robotic arm is fabricated and mounted on top of an endoscope model to provide a proof of concept of simple robotic mechanisms that could be useful in a surgical scenario.}, url = {http://dx.doi.org/10.1109/ICRA.2016.7487203}, author = {Sheila Russo and Ranzani, Tommaso and Joshua B. Gafford and Walsh, Conor J. and Wood, Robert J.} } @proceedings {703196, title = {Soft Wearable Robots Can Reduce the Energy Cost of Poststroke Walking: A Proof-of-Concept Study}, journal = {Combined Sessions Meeting of the American Physical Therapy Association (APTA CSM)}, year = {2016}, month = {17-20 Feb 2016}, address = {Anaheim, CA}, author = {Louis N. Awad and Jaehyun Bae and De Rossi, Stefano M.M. and Kathleen O{\textquoteright}Donnell and Kathryn L. Hendron and Kenneth G. Holt and Terry Ellis and Conor J Walsh} } @proceedings {dw2016malcolm, title = {Study of the contribution of negative work assistance at the ankle with a multi-articular soft exosuit during loaded walking}, journal = {Dynamic Walking}, year = {2016}, month = {4-7 June 2016}, address = {Holly, Michigan, USA}, author = {Philippe Malcolm and Lee, Sangjun and Simona Crea and Christopher Siviy and Saucedo, Fabricio and Ignacio B. Galiana and Fausto Panizzolo and Kenneth G. Holt and Walsh, Conor J.} } @proceedings {dw2016yandell, title = {Systematic evaluation of human-exosuit physical interfaces}, journal = {Dynamic Walking}, year = {2016}, month = {4-7 June 2016}, address = {Holly, Michigan, USA}, author = {Matthew B. Yandell and Dmitry Popov and Brendan Quinlivan and Walsh, Conor J. and Karl E. Zelik} } @conference {697851, title = {IMU-based Iterative Control for Hip Extension Assistance with a Soft Exosuit}, booktitle = {IEEE International Conference on Robotics and Automation (ICRA)}, year = {2016}, month = {16-21 May}, pages = {3501-3508}, address = {Stockholm, Sweden}, abstract = { In this paper we describe an IMU-based iterative controller for hip extension assistance where the onset timing of assistance is based on an estimate of the maximum hip flexion angle. The controller was implemented on a mono-articular soft exosuit coupled to a lab-based multi-joint actuation platform that enables rapid reconfiguration of different sensors and control strategy implementation. The controller design is motivated by a model of the suit-human interface and utilizes an iterative control methodology that includes gait detection and step-by-step actuator position profile generation to control the onset timing, peak timing, and peak magnitude of the delivered force. This controller was evaluated on eight subjects walking on a treadmill at a speed of 1.5 m/s while carrying a load of 23 kg. Results showed that assistance could be delivered reliably across subjects. Specifically, for a given profile, the average delivered force started concurrently with the timing of the maximum hip flexion angle and reached its peak timing 22.7 {\textpm} 0.63\% later in the gait cycle (desired 23\%) with a peak magnitude of 198.2 {\textpm} 1.6 N (desired 200 N), equivalent to an average peak torque of 30.5 {\textpm} 4.7 Nm. This control approach was used to assess the metabolic effect of four different assistive profiles. Metabolic reductions ranging from 5.7\% to 8.5\% were found when comparing the powered conditions with the unpowered condition. This work enables studies to assess the biomechanical and physiological responses to different assistive profiles to determine the optimal hip extension assistance during walking. }, url = {http://dx.doi.org/10.1109/ICRA.2016.7487530}, author = {Ye Ding and Ignacio Galiana and Christopher Siviy and Panizzolo, Fausto A. and Conor J Walsh} }