ResearchPad - robotics https://www.researchpad.co Default RSS Feed en-us © 2020 Newgen KnowledgeWorks <![CDATA[A practical 3D-printed soft robotic prosthetic hand with multi-articulating capabilities]]> https://www.researchpad.co/article/elastic_article_14594 Soft robotic hands with monolithic structure have shown great potential to be used as prostheses due to their advantages to yield light weight and compact designs as well as its ease of manufacture. However, existing soft prosthetic hands design were often not geared towards addressing some of the practical requirements highlighted in prosthetics research. The gap between the existing designs and the practical requirements significantly hampers the potential to transfer these designs to real-world applications. This work addressed these requirements with the consideration of the trade-off between practicality and performance. These requirements were achieved through exploiting the monolithic 3D printing of soft materials which incorporates membrane enclosed flexure joints in the finger designs, synergy-based thumb motion and cable-driven actuation system in the proposed hand prosthesis. Our systematic design (tentatively named X-Limb) achieves a weight of 253gr, three grasps types (with capability of individual finger movement), power-grip force of 21.5N, finger flexion speed of 1.3sec, a minimum grasping cycles of 45,000 (while maintaining its original functionality) and a bill of material cost of 200 USD (excluding quick disconnect wrist but without factoring in the cost reduction through mass production). A standard Activities Measure for Upper-Limb Amputees benchmark test was carried out to evaluate the capability of X-Limb in performing grasping task required for activities of daily living. The results show that all the practical design requirements are satisfied, and the proposed soft prosthetic hand is able to perform all the real-world grasping tasks of the benchmark tests, showing great potential in improving life quality of individuals with upper limb loss.

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<![CDATA[Is the amount of carbon dioxide gas used in urologic laparoscopic surgeries associated with postoperative pain?]]> https://www.researchpad.co/article/N1c2e0b07-8674-4fd7-98d0-f7cb618a11e9 We measured how much CO2 gas was used in urologic laparoscopic surgeries and studied whether the amount of gas was associated with postoperative pain.Materials and MethodsFour hundred sixty-three patients underwent urologic laparoscopic surgeries by a single surgeon. All surgeries were performed by a transperitoneal approach under a 15-mm Hg pneumoperitoneum using CO2 gas. The amount of CO2 was measured. Neuromuscular blockade with rocuronium was performed during the surgery and patient-controlled analgesia was also applied. Postoperative pain was assessed four times for 24 hours using a 10-point visual analogue scale.ResultsThe mean laparoscopic time was 75.65±38.19 minutes and the mean amount of CO2 gas used was 415.70±190.68 L. The mean score on the postoperative pain scale was 6.37±1.48 for 12 hours (sum of measurements taken at 6 and 12 hours after the surgery) and 11.72±2.46 for 24 hours (sum of measurements at 6, 12, 18, and 24 hours). In the statistical analysis, there were no correlations between the amount of CO2 used and pain scores for 12 and 24 hours postoperatively. There were no correlations between laparoscopic time and pain scores for 12 or 24 hours postoperatively. There were also no correlations between operative method and pain scores for 12 or 24 hours postoperatively.ConclusionsWe recorded the amount of CO2 gas used for each laparoscopic surgery. There was no correlation between the amount of CO2 used and postoperative pain. The lack of correlation may have been because the surgery was performed under anesthesia with deep neuromuscular blockade. ]]> <![CDATA[Predictive factors and radiological findings of adrenohepatic adhesion during laparoscopic adrenalectomy]]> https://www.researchpad.co/article/Nf547e5c5-3bc1-4e91-a782-98b64a7e47d9 This retrospective study aimed to identify predictive factors and imaging features of adrenohepatic adhesion found during laparoscopic right adrenalectomy.Materials and MethodsAltogether, 77 patients underwent laparoscopic right adrenalectomy between January 2005 and December 2018. Adrenohepatic adhesion was defined as strict adhesion that required either partial adrenalectomy with coagulation of residual tissue or partial hepatectomy to accomplish complete resection. We assessed their surgical video records to determine if adrenohepatic adhesion was present. Age, sex, body mass index, tumor size, tumor diagnosis and radiological findings (attachment between the liver and the adrenal gland, diameters of the right and left adrenal veins and its ratio) were evaluated as preoperative variables.ResultsAdrenohepatic adhesion was present in 11 of the 77 patients (14.3%). Age, sex, and body mass index were not statistically significant factors. Tumor size was significantly small in adhesion group (14.2 mm vs. 25.9 mm, p=0.02). Attachment to the liver and adrenal gland was frequently seen regardless of the adhesion. The mean right/left adrenal veins diameters ratio was significantly lower in the adhesion group (0.8 vs. 1.1, p=0.01). Multivariate logistic regression analysis demonstrated the right/left adrenal veins diameters ratio was the only significant predictor of adhesion. The sensitivity, specificity, negative predictive value and positive predictive value were 0.82, 0.76, 0.43, and 0.95 respectively when the optimal cutoff value for the ratio was 0.9 (area under the curve, 0.75; 95% confidence interval, 0.60–0.90).ConclusionsThe right/left adrenal veins diameters ratio was possible predictor of adrenohepatic adhesion. ]]> <![CDATA[Exact flow of particles using for state estimations in unmanned aerial systems` navigation]]> https://www.researchpad.co/article/Nb8d1b185-24ca-4749-9cc9-bbc7ade34d0a

The navigation is a substantial issue in the field of robotics. Simultaneous Localization and Mapping (SLAM) is a principle for many autonomous navigation applications, particularly in the Global Navigation Satellite System (GNSS) denied environments. Many SLAM methods made substantial contributions to improve its accuracy, cost, and efficiency. Still, it is a considerable challenge to manage robust SLAM, and there exist several attempts to find better estimation algorithms for it. In this research, we proposed a novel Bayesian filtering based Airborne SLAM structure for the first time in the literature. We also presented the mathematical background of the algorithm, and the SLAM model of an autonomous aerial vehicle. Simulation results emphasize that the new Airborne SLAM performance with the exact flow of particles using for recursive state estimations superior to other approaches emerged before, in terms of accuracy and speed of convergence. Nevertheless, its computational complexity may cause real-time application concerns, particularly in high-dimensional state spaces. However, in Airborne SLAM, it can be preferred in the measurement environments that use low uncertainty sensors because it gives more successful results by eliminating the problem of degeneration seen in the particle filter structure.

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<![CDATA[Comparison of surgical outcomes between lateral and posterior approaches for retroperitoneal laparoscopic adrenalectomy: A single surgeon's experience]]> https://www.researchpad.co/article/N0b9f67c6-02ab-4a6d-9a06-807aa9ebab24

Purpose

To compare surgical outcomes between the lateral and the posterior approach for retroperitoneal laparoscopic adrenalectomy (RLA).

Materials and Methods

We retrospectively reviewed the records of 130 patients who underwent RLA for adrenal tumors by a single surgeon between January 2015 and December 2018. Patient characteristics and perioperative outcomes were analyzed and compared between two surgical groups: lateral approach (n=56) and posterior approach (n=74).

Results

There were no significant differences in perioperative outcomes between the two groups except for operative time (lateral approach, 105.4±41.21 minutes vs. posterior approach, 71.5±31.51 minutes; p=0.001). In the lateral approach group, two patients (3.6%) underwent open conversion, but there were no major complications in either group (Clavien-Dindo classification ≥3). Male sex was associated with an operative time of ≥90 minutes in the univariate analysis (p=0.019), but this effect did not remain significant in the multivariate analysis. In the multivariate analysis, large tumor size (>5 cm; p=0.020) and preoperative diagnosis of malignancy (p=0.043) were significantly associated with an operative time of ≥90 minutes.

Conclusions

Both the lateral and posterior approaches for RLA were performed safely with similar operative outcomes and are therefore comparable options for the treatment of adrenal tumors. In addition, large tumor size and preoperative diagnosis of malignancy are associated with longer operative times.

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<![CDATA[Robotic hand illusion with tactile feedback: Unravelling the relative contribution of visuotactile and visuomotor input to the representation of body parts in space]]> https://www.researchpad.co/article/5c521842d5eed0c484797949

The rubber hand illusion describes a phenomenon in which participants experience a rubber hand as being part of their body by the synchronous application of visuotactile stimulation to the real and the artificial limb. In the recently introduced robotic hand illusion (RobHI), a robotic hand is incorporated into one’s body representation due to the integration of synchronous visuomotor information. However, there are no setups so far that combine visuotactile and visuomotor feedback, which is expected to unravel mechanisms that cannot be detected in experimental designs applying this information in isolation. We developed a robotic hand, controlled by a sensor glove and equipped with pressure sensors, and varied systematically and separately the synchrony for motor feedback (MF) and tactile feedback (TF). In Experiment 1, we implemented a ball-grasping task and assessed the perceived proprioceptive drift of one’s own hand as a behavioral measure of the spatial calibration of body coordinates as well as explicit embodiment experiences by a questionnaire. Results revealed significant main effects of both MF and TF for proprioceptive drift data, but we only observed main effects for MF on perceived embodiment. Furthermore, for the proprioceptive drift we found that synchronous feedback in one factor compensates for asynchronous feedback in the other. In Experiment 2, including a new sample of naïve participants, we further explored this finding by adding unimodal conditions, in which we manipulated the presence or absence of MF and/or TF. These findings replicated the results from Experiment 1 and we further found evidence for a supper-additive multisensory effect on spatial body representation caused by the presence of both factors. Results on conscious body perception were less consistent across both experiments. The findings indicate that sensory and motor input equally contribute to the representation of spatial body coordinates which for their part are subject to multisensory enhancing effects. The results outline the potential of human-in-the-loop approaches and might have important implications for clinical applications such as for the future design of robotic prostheses.

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<![CDATA[Improved and semi-automated reductive β-elimination workflow for higher throughput protein O-glycosylation analysis]]> https://www.researchpad.co/article/5c61b7c0d5eed0c484937ef2

Protein O-glycosylation has shown to be critical for a wide range of biological processes, resulting in an increased interest in studying the alterations in O-glycosylation patterns of biological samples as disease biomarkers as well as for patient stratification and personalized medicine. Given the complexity of O-glycans, often a large number of samples have to be analysed in order to obtain conclusive results. However, most of the O-glycan analysis work done so far has been performed using glycoanalytical technologies that would not be suitable for the analysis of large sample sets, mainly due to limitations in sample throughput and affordability of the methods. Here we report a largely automated system for O-glycan analysis. We adapted reductive β-elimination release of O-glycans to a 96-well plate system and transferred the protocol onto a liquid handling robot. The workflow includes O-glycan release, purification and derivatization through permethylation followed by MALDI-TOF-MS. The method has been validated according to the ICH Q2 (R1) guidelines for the validation of analytical procedures. The semi-automated reductive β-elimination system enabled for the characterization and relative quantitation of O-glycans from commercially available standards. Results of the semi-automated method were in good agreement with the conventional manual in-solution method while even outperforming it in terms of repeatability. Release of O-glycans for 96 samples was achieved within 2.5 hours, and the automated data acquisition on MALDI-TOF-MS took less than 1 minute per sample. This largely automated workflow for O-glycosylation analysis showed to produce rapid, accurate and reliable data, and has the potential to be applied for O-glycan characterization of biological samples, biopharmaceuticals as well as for biomarker discovery.

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<![CDATA[Comparison of oncological and perioperative outcomes of open, laparoscopic, and robotic nephroureterectomy approaches in patients with non-metastatic upper-tract urothelial carcinoma]]> https://www.researchpad.co/article/5c3e5076d5eed0c484d81f2c

Background

To compare the oncological and perioperative outcomes of different nephroureterectomy approaches in patients with non-metastatic upper tract urothelial carcinoma (UTUC).

Methods

We retrospectively analyzed the data of 422 patients who underwent open, laparoscopic, or robotic nephroureterectomy for non-metastatic UTUC. Perioperative and postoperative survival outcomes were compared using Kaplan-Meier analyses and Cox-proportional hazard models.

Results

Of the patients, 161, 137, and 124 were treated with an open, laparoscopic, and robotic approach, respectively. Laparoscopic and robotic approaches involved significantly less blood loss (p = 0.001), shorter hospital stay (p < 0.001), and longer operation time (p < 0.001) compared with the open approach. There were no significant differences in intraoperative complications (open, 8.1%; laparoscopic, 5.1%; robotic, 7.3%; p = 0.363) or early postoperative complications (open, 14.9%; laparoscopic, 14.6%; robotic, 13.7%; p = 0.880). The laparoscopic and robotic groups showed significantly less postoperative analgesic use (p = 0.015). The robotic group showed significantly longer progression-free, cancer-specific, and overall survivals than the open approach group on univariate Kaplan-Meier analysis, but surgery type was not significantly associated with survival outcomes per multivariate Cox proportional tests (all p-values > 0.05).

Conclusion

The laparoscopic and robotic approaches yielded better perioperative outcomes, such as less intraoperative bleeding, shorter hospital stays, less analgesic usage, and non-inferior oncological outcomes, compared with the open approach. Further prospective studies are needed to compare these surgical techniques.

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<![CDATA[Adaptive coupling influences generalization of sensorimotor learning]]> https://www.researchpad.co/article/5c2400b9d5eed0c484098c9f

Sensorimotor learning typically shows generalization from one context to another. Models of sensorimotor learning characterize this with a fixed generalization function that couples learning between contexts. Here we examine whether such coupling is indeed fixed or changes with experience. We examine the interaction between motor memories for novel dynamics during reciprocating, back and forth reaching movements. Subjects first experienced a force field for one movement direction and we used channel trials to assess generalization on the reciprocal movements. This showed minimal coupling such that errors experienced for one movement direction did not lead to adaptation for the other. However, after subjects had experienced a force field for both movement directions concurrently, a coupling developed between the corresponding motor memories. That is, on re-exposure for one direction there was a significant adaptation for movements in the other direction. The coupling was specific to the errors experienced, with minimal coupling when the errors had the opposite sign to those experienced during adaptation. We developed a state-space model in which the states for the two movement directions are represented by separate, yet potentially coupled learning processes. The coupling in the model controlled the extent to which each learning process was updated by the errors experienced on the other movement direction. We show that the coupling relies on a memory trace of the consecutive errors experienced for both movement directions. Our results suggest that the generalization of motor learning is an adaptive process, reflecting the relation between errors experienced across different movements.

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<![CDATA[A new plan quality objective function for determining optimal collimator combinations in prostate cancer treatment with stereotactic body radiation therapy using CyberKnife]]> https://www.researchpad.co/article/5c06f034d5eed0c484c6d3a1

Stereotactic body radiation therapy with CyberKnife for prostate cancer has long treatment times compared with conventional radiotherapy. This arises the need for designing treatment plans with short execution times. We propose an objective function for plan quality evaluation, which was used to determine an optimal combination between small and large collimators based on short treatment times and clinically acceptable dose distributions. Data from 11 prostate cancer patients were used. For each patient, 20 plans were created based on all combinations between one small (⌀ 10–25 mm) and one large (⌀ 35–60 mm) Iris collimator size. The objective function was assigned to each combination as a penalty, such that plans with low penalties were considered superior. This function considered the achievement of dosimetric planning goals, tumor control probability, normal tissue complication probability, relative seriality parameter, and treatment time. Two methods were used to determine the optimal combination. First, we constructed heat maps representing the mean penalty values and standard deviations of the plans created for each collimator combination. The combination giving a plan with the smallest mean penalty and standard deviation was considered optimal. Second, we created two groups of superior plans: group A plans were selected by histogram analysis and group B plans were selected by choosing the plan with the lowest penalty from each patient. In both groups, the most used small and large collimators were assumed to represent the optimal combination. The optimal combinations obtained from the heat maps included the 25 mm as a small collimator, giving small/large collimator sizes of 25/35, 25/40, 25/50, and 25/60 mm. The superior-group analysis indicated that 25/50 mm was the optimal combination. The optimal Iris combination for prostate cancer treatment using CyberKnife was determined to be a collimator size between 25 mm (small) and 50 mm (large).

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<![CDATA[Low-resistive vibratory penetration in granular media]]> https://www.researchpad.co/article/5989db53ab0ee8fa60bdca0e

Non-cohesive materials such as sand, dry snow or cereals are encountered in various common circumstances, from everyday situations to industry. The process of digging into these materials remains a challenge to most animals and machines. Within the animal kingdom, different strategies are employed to overcome this issue, including excavation methods used by ants, the two-anchor strategy employed by soft burrowers such as razor-clams, and undulatory motions exhibited by sandfish lizards. Despite the development of technology to mimic these techniques in diggers and robots, the limitations of animals and machines may differ, and mimicry of natural processes is not necessarily the most efficient technological strategy. This study presents evidence that the resisting force for the penetration of an intruder into a dry granular media can be reduced by one order of magnitude with small amplitude (A ≃ 10 μm) and low frequency (f = 50 − 200 Hz) mechanical vibrations. This observed result is attributed to the local fluidization of the granular bed which induces the rupture of force chains. The drop in resistive force on entering dry granular materials may be relevant in technological development in order to increase the efficiency of diggers and robots.

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<![CDATA[Evaluation of stiffness feedback for hard nodule identification on a phantom silicone model]]> https://www.researchpad.co/article/5989db4fab0ee8fa60bdbc2f

Haptic information in robotic surgery can significantly improve clinical outcomes and help detect hard soft-tissue inclusions that indicate potential abnormalities. Visual representation of tissue stiffness information is a cost-effective technique. Meanwhile, direct force feedback, although considerably more expensive than visual representation, is an intuitive method of conveying information regarding tissue stiffness to surgeons. In this study, real-time visual stiffness feedback by sliding indentation palpation is proposed, validated, and compared with force feedback involving human subjects. In an experimental tele-manipulation environment, a dynamically updated color map depicting the stiffness of probed soft tissue is presented via a graphical interface. The force feedback is provided, aided by a master haptic device. The haptic device uses data acquired from an F/T sensor attached to the end-effector of a tele-manipulated robot. Hard nodule detection performance is evaluated for 2 modes (force feedback and visual stiffness feedback) of stiffness feedback on an artificial organ containing buried stiff nodules. From this artificial organ, a virtual-environment tissue model is generated based on sliding indentation measurements. Employing this virtual-environment tissue model, we compare the performance of human participants in distinguishing differently sized hard nodules by force feedback and visual stiffness feedback. Results indicate that the proposed distributed visual representation of tissue stiffness can be used effectively for hard nodule identification. The representation can also be used as a sufficient substitute for force feedback in tissue palpation.

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<![CDATA[View-Invariant Visuomotor Processing in Computational Mirror Neuron System for Humanoid]]> https://www.researchpad.co/article/5989da1cab0ee8fa60b7d5bf

Mirror neurons are visuo-motor neurons found in primates and thought to be significant for imitation learning. The proposition that mirror neurons result from associative learning while the neonate observes his own actions has received noteworthy empirical support. Self-exploration is regarded as a procedure by which infants become perceptually observant to their own body and engage in a perceptual communication with themselves. We assume that crude sense of self is the prerequisite for social interaction. However, the contribution of mirror neurons in encoding the perspective from which the motor acts of others are seen have not been addressed in relation to humanoid robots. In this paper we present a computational model for development of mirror neuron system for humanoid based on the hypothesis that infants acquire MNS by sensorimotor associative learning through self-exploration capable of sustaining early imitation skills. The purpose of our proposed model is to take into account the view-dependency of neurons as a probable outcome of the associative connectivity between motor and visual information. In our experiment, a humanoid robot stands in front of a mirror (represented through self-image using camera) in order to obtain the associative relationship between his own motor generated actions and his own visual body-image. In the learning process the network first forms mapping from each motor representation onto visual representation from the self-exploratory perspective. Afterwards, the representation of the motor commands is learned to be associated with all possible visual perspectives. The complete architecture was evaluated by simulation experiments performed on DARwIn-OP humanoid robot.

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<![CDATA[A Simple State-Determined Model Reproduces Entrainment and Phase-Locking of Human Walking]]> https://www.researchpad.co/article/5989da20ab0ee8fa60b7ebb0

Theoretical studies and robotic experiments have shown that asymptotically stable periodic walking may emerge from nonlinear limit-cycle oscillators in the neuro-mechanical periphery. We recently reported entrainment of human gait to periodic mechanical perturbations with two essential features: 1) entrainment occurred only when the perturbation period was close to the original (preferred) walking period, and 2) entrainment was always accompanied by phase locking so that the perturbation occurred at the end of the double-stance phase. In this study, we show that a highly-simplified state-determined walking model can reproduce several salient nonlinear limit-cycle behaviors of human walking: 1) periodic gait that is 2) asymptotically stable; 3) entrainment to periodic mechanical perturbations only when the perturbation period is close to the model's unperturbed period; and 4) phase-locking to locate the perturbation at the end of double stance. Importantly, this model requires neither supra-spinal control nor an intrinsic self-sustaining neural oscillator such as a rhythmic central pattern generator. Our results suggest that several prominent limit-cycle features of human walking may stem from simple afferent feedback processes without significant involvement of supra-spinal control or a self-sustaining oscillatory neural network.

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<![CDATA[Robotic Assisted Radical Cystectomy with Extracorporeal Urinary Diversion Does Not Show a Benefit over Open Radical Cystectomy: A Systematic Review and Meta-Analysis of Randomised Controlled Trials]]> https://www.researchpad.co/article/5989d9e0ab0ee8fa60b6971a

Background

The number of robotic assisted radical cystectomy (RARC) procedures is increasing despite the lack of Level I evidence showing any advantages over open radical cystectomy (ORC). However, several systematic reviews with meta-analyses including non-randomised studies, suggest an overall benefit for RARC compared to ORC. We performed a systematic review with meta-analysis of randomised controlled trials (RCTs) to evaluate the perioperative morbidity and efficacy of RARC compared to ORC in patients with bladder cancer.

Methods

Literature searches of Medline/Pubmed, Embase, Web of Science and clinicaltrials.gov databases up to 10th March 2016 were performed. The inclusion criteria for eligible studies were RCTs which compared perioperative outcomes of ORC and RARC for bladder cancer. Primary objective was perioperative and histopathological outcomes of RARC versus ORC while the secondary objective was quality of life assessment (QoL), oncological outcomes and cost analysis.

Results

Four RCTs (from 5 articles) met the inclusion criteria, with a total of 239 patients all with extracorporeal urinary diversion. Patient demographics and clinical characteristics of RARC and ORC patients were evenly matched. There was no significant difference between groups in perioperative morbidity, length of stay, positive surgical margin, lymph node yield and positive lymph node status. RARC group had significantly lower estimated blood loss (p<0.001) and wound complications (p = 0.03) but required significantly longer operating time (p<0.001). QoL was not measured uniformly across trials and cost analysis was reported in one RCTs. A test for heterogeneity did highlight differences across operating time of trials suggesting that surgeon experience may influence outcomes.

Conclusions

This study does not provide evidence to support a benefit for RARC compared to ORC. These results may not have inference for RARC with intracorporeal urinary diversion. Well-designed trials with appropriate endpoints conducted by equally experienced ORC and RARC surgeons will be needed to address this.

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<![CDATA[Task-Level Strategies for Human Sagittal-Plane Running Maneuvers Are Consistent with Robotic Control Policies]]> https://www.researchpad.co/article/5989da3cab0ee8fa60b88305

The strategies that humans use to control unsteady locomotion are not well understood. A “spring-mass” template comprised of a point mass bouncing on a sprung leg can approximate both center of mass movements and ground reaction forces during running in humans and other animals. Legged robots that operate as bouncing, “spring-mass” systems can maintain stable motion using relatively simple, distributed feedback rules. We tested whether the changes to sagittal-plane movements during five running tasks involving active changes to running height, speed, and orientation were consistent with the rules used by bouncing robots to maintain stability. Changes to running height were associated with changes to leg force but not stance duration. To change speed, humans primarily used a “pogo stick” strategy, where speed changes were associated with adjustments to fore-aft foot placement, and not a “unicycle” strategy involving systematic changes to stance leg hip moment. However, hip moments were related to changes to body orientation and angular speed. Hip moments could be described with first order proportional-derivative relationship to trunk pitch. Overall, the task-level strategies used for body control in humans were consistent with the strategies employed by bouncing robots. Identification of these behavioral strategies could lead to a better understanding of the sensorimotor mechanisms that allow for effective unsteady locomotion.

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<![CDATA[Interactive Language Learning by Robots: The Transition from Babbling to Word Forms]]> https://www.researchpad.co/article/5989db09ab0ee8fa60bc973c

The advent of humanoid robots has enabled a new approach to investigating the acquisition of language, and we report on the development of robots able to acquire rudimentary linguistic skills. Our work focuses on early stages analogous to some characteristics of a human child of about 6 to 14 months, the transition from babbling to first word forms. We investigate one mechanism among many that may contribute to this process, a key factor being the sensitivity of learners to the statistical distribution of linguistic elements. As well as being necessary for learning word meanings, the acquisition of anchor word forms facilitates the segmentation of an acoustic stream through other mechanisms. In our experiments some salient one-syllable word forms are learnt by a humanoid robot in real-time interactions with naive participants. Words emerge from random syllabic babble through a learning process based on a dialogue between the robot and the human participant, whose speech is perceived by the robot as a stream of phonemes. Numerous ways of representing the speech as syllabic segments are possible. Furthermore, the pronunciation of many words in spontaneous speech is variable. However, in line with research elsewhere, we observe that salient content words are more likely than function words to have consistent canonical representations; thus their relative frequency increases, as does their influence on the learner. Variable pronunciation may contribute to early word form acquisition. The importance of contingent interaction in real-time between teacher and learner is reflected by a reinforcement process, with variable success. The examination of individual cases may be more informative than group results. Nevertheless, word forms are usually produced by the robot after a few minutes of dialogue, employing a simple, real-time, frequency dependent mechanism. This work shows the potential of human-robot interaction systems in studies of the dynamics of early language acquisition.

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<![CDATA[Chondrocyte Deformations as a Function of Tibiofemoral Joint Loading Predicted by a Generalized High-Throughput Pipeline of Multi-Scale Simulations]]> https://www.researchpad.co/article/5989da00ab0ee8fa60b73bdf

Cells of the musculoskeletal system are known to respond to mechanical loading and chondrocytes within the cartilage are not an exception. However, understanding how joint level loads relate to cell level deformations, e.g. in the cartilage, is not a straightforward task. In this study, a multi-scale analysis pipeline was implemented to post-process the results of a macro-scale finite element (FE) tibiofemoral joint model to provide joint mechanics based displacement boundary conditions to micro-scale cellular FE models of the cartilage, for the purpose of characterizing chondrocyte deformations in relation to tibiofemoral joint loading. It was possible to identify the load distribution within the knee among its tissue structures and ultimately within the cartilage among its extracellular matrix, pericellular environment and resident chondrocytes. Various cellular deformation metrics (aspect ratio change, volumetric strain, cellular effective strain and maximum shear strain) were calculated. To illustrate further utility of this multi-scale modeling pipeline, two micro-scale cartilage constructs were considered: an idealized single cell at the centroid of a 100×100×100 μm block commonly used in past research studies, and an anatomically based (11 cell model of the same volume) representation of the middle zone of tibiofemoral cartilage. In both cases, chondrocytes experienced amplified deformations compared to those at the macro-scale, predicted by simulating one body weight compressive loading on the tibiofemoral joint. In the 11 cell case, all cells experienced less deformation than the single cell case, and also exhibited a larger variance in deformation compared to other cells residing in the same block. The coupling method proved to be highly scalable due to micro-scale model independence that allowed for exploitation of distributed memory computing architecture. The method’s generalized nature also allows for substitution of any macro-scale and/or micro-scale model providing application for other multi-scale continuum mechanics problems.

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<![CDATA[Intelligence-Augmented Rat Cyborgs in Maze Solving]]> https://www.researchpad.co/article/5989dadeab0ee8fa60bbabe9

Cyborg intelligence is an emerging kind of intelligence paradigm. It aims to deeply integrate machine intelligence with biological intelligence by connecting machines and living beings via neural interfaces, enhancing strength by combining the biological cognition capability with the machine computational capability. Cyborg intelligence is considered to be a new way to augment living beings with machine intelligence. In this paper, we build rat cyborgs to demonstrate how they can expedite the maze escape task with integration of machine intelligence. We compare the performance of maze solving by computer, by individual rats, and by computer-aided rats (i.e. rat cyborgs). They were asked to find their way from a constant entrance to a constant exit in fourteen diverse mazes. Performance of maze solving was measured by steps, coverage rates, and time spent. The experimental results with six rats and their intelligence-augmented rat cyborgs show that rat cyborgs have the best performance in escaping from mazes. These results provide a proof-of-principle demonstration for cyborg intelligence. In addition, our novel cyborg intelligent system (rat cyborg) has great potential in various applications, such as search and rescue in complex terrains.

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<![CDATA[Refractoriness in Sustained Visuo-Manual Control: Is the Refractory Duration Intrinsic or Does It Depend on External System Properties?]]> https://www.researchpad.co/article/5989daf4ab0ee8fa60bc2600

Researchers have previously adopted the double stimulus paradigm to study refractoriness in human neuromotor control. Currently, refractoriness, such as the Psychological Refractory Period (PRP) has only been quantified in discrete movement conditions. Whether refractoriness and the associated serial ballistic hypothesis generalises to sustained control tasks has remained open for more than sixty years. Recently, a method of analysis has been presented that quantifies refractoriness in sustained control tasks and discriminates intermittent (serial ballistic) from continuous control. Following our recent demonstration that continuous control of an unstable second order system (i.e. balancing a ‘virtual’ inverted pendulum through a joystick interface) is unnecessary, we ask whether refractoriness of substantial duration (∼200 ms) is evident in sustained visual-manual control of external systems. We ask whether the refractory duration (i) is physiologically intrinsic, (ii) depends upon system properties like the order (0, 1st, and 2nd) or stability, (iii) depends upon target jump direction (reversal, same direction). Thirteen participants used discrete movements (zero order system) as well as more sustained control activity (1st and 2nd order systems) to track unpredictable step-sequence targets. Results show a substantial refractory duration that depends upon system order (250, 350 and 550 ms for 0, 1st and 2nd order respectively, n = 13, p<0.05), but not stability. In sustained control refractoriness was only found when the target reverses direction. In the presence of time varying actuators, systems and constraints, we propose that central refractoriness is an appropriate control mechanism for accommodating online optimization delays within the neural circuitry including the more variable processing times of higher order (complex) input-output relations.

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