Path Kinematics Research Articles

Evaluation of foramen locating accuracy of an endodontic motor integrated with electronic foramen employing optimal glide path kinematics.

This study aimed to evaluate the accuracy of the auto apical function in the maintenance of the apical limit of instrumentation during glide path procedures when associated to OGP kinematics of Tri Auto ZX2, compared to the continuous rotation of the same motor, as well as Root ZX II and VDW Gold. Forty-eight extracted human mandibular single-rooted premolars were selected. After endodontic access, cervical pre-flaring was performed using size 30, 0.10 taper rotary instruments, and the apical foramen size was standardized to 200μm. Teeth were randomly divided into four groups (n = 12) according to the device and kinematics. For all the groups, the Auto Apical Stop function (AAS) was set to the 0.0 mark. Glide path instruments size 25, .01 taper were activated inside the canals until the apical limit was reached. Then, the files were fixed with cyanoacrylate to the teeth and decoupled from the equipment. Data were statistically analyzed in GraphPad Prism 6.0 software with the significance set at 5% (Kruskal-Wallis tests). There was no difference in the mean deviation between the groups. No significant difference was found among the groups when the distributions and percentages of differences between the file tip and the apical foramen were compared (P > 0.05). The use of auto apical function at the 0.0 mark of all tested devices provided an adequate control of the apical limit during glide path preparation. Foramen locating accuracy of Tri Auto ZX2 in OGP kinematics was similar to those of Tri Auto ZX2, Root ZX II, and VDW Gold in continuous kinematics. Clinical strategies in canal negotiation and glide path as OGP motion associated to electronic foramen locators could reduce iatrogenic risk of deviation and file fractures and create an easier initial preparation to facilitate endodontic procedures.

Muscle loaded stability reflects ligament-based stability in TKA: a cadaveric study.

This paper aims at evaluating the effects of muscle load on knee kinematics and stability after TKA and second at evaluating the effect of TKA surgery on knee kinematics and stability; and third, at correlating the stability in passive conditions and the stability in active, muscle loaded conditions. Fourteen fresh frozen cadaveric knee specimens were tested under passive and active condition with and without external loads involving a varus/valgus and internal/external rotational torque before and after TKA surgery using two in-house developed and previously validated test setups. Introduction of muscle force resulted in increased valgus (0.98°) and internal rotation of the femur (4.64°). TKA surgery also affected the neutral path kinematics, resulting in more varus (1.25°) and external rotation of the femur (5.22°). All laxities were significantly reduced by the introduction of the muscle load and after implantation of the TKA. The presence of the implant significantly affects the active varus/valgus laxity. This contrasts with the rotational laxity, in which case the passive laxity is the main determinant for the active laxity. For the varus/valgus laxity, the passive laxity is also a significant predictor of the active laxity. Knee stability is clearly affected by the presence of muscle load. This points to the relevance of appropriate rehabilitation with focus on avoiding muscular atrophy. At the same time, the functional, muscle loaded stability strongly relates to the passive, ligament-based stability. It remains therefore important to assess knee stability at the time of surgery, since the passive laxity is the only predictor for functional stability in the operating theatre. Case series, Level IV.

Influence of glide path kinematics during endodontic treatment on the occurrence and intensity of intraoperative and postoperative pain: a systematic review of randomized clinical trials

BackgroundPreliminary canal enlargement (glide path preparation) may play a significant role in the development of pain. The aim of this systematic review of randomized clinical trials was to assess the influence of glide path kinematics during endodontic treatment on the occurrence and intensity of intraoperative and postoperative pain.MethodsA search was performed in June 2019 in six electronic databases (PubMed, Scopus, LILACS, SciELO, Embase and Web of Science) and two grey literature databases (OpenGrey and OpenThesis). The bibliographic references of the eligible articles were also hand-searched. The included clinical studies assessed the occurrence and intensity of intraoperative and/or postoperative pain after root canal preparation without glide path preparation (WGP) or with glide path preparation using manual (M-GP), continuous rotary (CR-GP), or reciprocating (R-GP) instruments. The primary outcome was the occurrence and intensity of intraoperative and postoperative pain, while analgesic consumption was the secondary outcome. The full texts of the eligible studies were analyzed by two reviewers who performed calibration exercises to verify the risk of bias and quality of the individual studies using the Joanna Briggs Institute Critical Appraisal tool.ResultsFrom 1283 identified articles, only six studies were included in the qualitative analysis of the results, with a total sample of 884 patients/teeth. Three studies presented a high risk of bias, while three studies presented a moderate risk. Two studies reported that CR-GP causes lower pain levels than M-GP and WGP, and three studies showed no differences between CR-GP and R-GP. Regarding analgesic consumption, two studies found no differences among glide path kinematics, and one study reported lower consumption for CR-GP than for M-GP. Because of the limited number of studies and methodological differences, no statistical analyses were performed for the glide path kinematics comparisons.ConclusionsCompelling evidence indicating a significantly different occurrence and intensity of pain among glide path kinematics is lacking.The systematic review protocol was registered in the PROSPERO database [CRD42020139989].

A validated combined musculotendon path and muscle-joint kinematics model for the human hand

Neuromusculoskeletal models provide a mathematical tool for understanding and simulating human motor control and neuromechanics. In this work, we propose a combined computational model for the musculotendon paths and muscle-joint kinematics for the human hand, including all extrinsic and intrinsic muscles. This model is implemented based on the anatomical descriptions and a human hand dissection study. The model takes joint angles as input and estimates the musculotendon lengths, length change rates, and excursion moment arms. The proposed model is simulated to generate according moment arms, which are compared with cadaver measurements available from literature in terms of similarity coefficient s. For most muscles compared, high similarity with for 92% of cases is achieved between the modeled and the measured moment arms. These results suggest the correctness of modeled moment arms and imply the feasibility of modeled musculotendon paths, lengths, and length change rates.

Immersion and invariance-based integrated guidance and control for unmanned aerial vehicle path following

ABSTRACTAn integrated guidance and control scheme is proposed on path following for the unmanned aerial vehicle. It is capable of handling the coupled non-linearities of the path's kinematics and the aircraft's dynamics independently. In the path coordinate, the guidance law is designed based on a nominal model, and the non-linearity of the path's kinematics is taken into full consideration. In the time coordinate, the flight control law is designed as a feed-forward controller, and it can guarantee the robustness of the guidance law with respect to the actual aircraft's dynamics. Instead of only employing Lyapunov method, the concept of immersion and invariance is also applied to explicitly analyse the stability in both time and path coordinates, and the asymptotic stability of the closed-loop system can be guaranteed. What is more, the regulation-based and immersion-based adaptive technologies are synthetically utilised to handle the unknown parameters. Finally, the numerical simulations demonstrate the effectiveness of the developed integrated guidance and control scheme.

Analysis of the loss of vehicle motion stability in the conditions of steering control disturbance

Disturbances in the vehicle motion may be caused by different factors and in many cases are the reason for dangerous traffic incidents. Disturbances within the human-vehicle system are particularly hazardous. An innovative method was designed for analyzing and simulating the process of loss of vehicle motion stability after interference in the steering system, e.g. by acting on the steering wheel by the passenger. The subject of the study is the theoretical and experimental analysis of the vehicle motion path kinematics together with the duration of the disturbance, driver’s reaction time and steering wheel turning angles. PC-Crash simulation software was employed for the purpose of studying the disturbance characteristics and their influence on the loss of vehicle motion stability. It is recognized that the studied issues are as yet poorly understood, the presented results expand our knowledge base in this area and can be employed for the purpose of analysis of actual traffic accidents.

Locomotor deficits in recently concussed athletes and matched controls during single and dual-task turning gait: preliminary results.

BackgroundThere is growing evidence that mild traumatic brain injury (concussion) can affect locomotor characteristics for prolonged periods of time even when physical signs and symptoms are absent. While most locomotor deficits post-concussion have involved straight walking, turning gait has received little attention despite its pervasiveness in everyday locomotion and athletic competition.MethodsThis study longitudinally examined kinematic characteristics during preplanned turning in a small sample of recently concussed athletes (n = 4) and healthy matched control athletes (n = 4) to examine potential deficits during single and dual-task turning gait over the initial 6 weeks post-injury, with a one-year follow-up. Turning path kinematics (curvature, obstacle clearance, path length), stride kinematics (stride length, stride width, stride time), and inclination angles were calculated from motion capture of participants walking around an obstacle.ResultsConcussed athletes had larger dual-task costs in turning speed and stride time compared to healthy controls. After controlling for speed and turn curvature, recently concussed athletes increased their inclination towards the inside of the turn over time and decreased their stride time compared to controls indicating a prolonged recovery. Kinematic differences between groups were estimated to recover to healthy levels between 100 and 300 days post-injury, suggesting future prospective longitudinal studies should span 6–12 months post-injury.ConclusionTurning gait should be included in future studies of concussion and may be a clinically useful tool. Future longitudinal studies should consider examining gait changes for up to 6–12 months post-injury.Electronic supplementary materialThe online version of this article (doi:10.1186/s12984-016-0177-y) contains supplementary material, which is available to authorized users.

Path planning and kinematics simulation of surfacing cladding for hot forging die

During the course of their work, a variety of damage and failure of hot forging die occurs and seriously affect the service life. Multi-layer metal hot forging die with functionally graded material structure can effectively extend the service life. In this paper, According to the needs of strengthening forging cavity, the CAD model of surfacing forming center was designed. Based on technological requirements of surface cladding for die cavity, the coupled movement equation of weld torch was established, and the trajectory of welding positioner and Cartesian robot kinematics was solved. The weld torch path was planned, according to the typical methods used in plane welding, and the surfacing path data was extracted by the secondary development of UG/OPEN. Then the kinematics solver program, which can output the control function of motion simulation, was written in MATLAB to solve the kinematics equation. Finally, in UG NX7.5, the kinematics simulation model was built to verify the correctness of mathematical model and the rationality of welding path planning. The above studies can provide a technical support for the die repair and manufacturing of a multilayer metal forging die.

Bi-unicondylar knee replacement laxity with changes to simulated soft tissue constraints

Unicondylar knee replacement systems have been shown to perform comparably to total knee replacements, while being much less surgically invasive. Proper ligament balancing, as well as knee laxity, has been shown to play an important role in optimizing kinematic behavior of these implant systems and improving long-term survival of the implant. This study investigates the effect of different simulated ligament laxity conditions of the anterior cruciate ligament and the posterior cruciate ligament on the resulting anteroposterior and mediolateral contact kinematics for medial and lateral pairs of UKR implants with flat and symmetric ultrahigh-molecular-weight polyethylene inserts during force-controlled ISO-14243-1 knee testing simulation. A novel method of capturing the tibiofemoral lowest point contact path was used to calculate the shear plane lowest point contact path kinematics in both the anteroposterior and the mediolateral directions. The results illustrated that multiple clinically relevant soft tissue configurations produce statistically different measured knee kinematics in unicondylar knee replacement systems than is seen in accepted "standard" knee simulator protocols with 95% confidence interval. The observed kinematic differences in anteroposterior and mediolateral movement from what was observed using standard wear testing protocols could aid in the development of unicondylar knee replacement design enhancements that are resistant to varying soft tissue deficiencies.

Robot Motion Synchronization in Cooperative Tasks

This paper discusses the problem of synchronizing multiple robots in cooperative tasks. The problem is divided in two parts: first the problem of synchronizing robots which are handling large objects that cannot be manipulated only by one robot (hard connected robots) is discussed; the problem is approached from the point of view of path planning, kinematics, and movement synchronization. An alternative of control using the force control and dynamics which solved by using a decentralized control structure is also presented. The second problem concerns robot synchronization in a shared workspace; here is presented a method of control for collision avoidance and time optimization for the robot tasks (assembly / disassembly). In the conclusion section the results from the experiments conducted on two SCARA type robots (Adept Cobra s600) are presented.

Changes in Bar Path Kinematics and Kinetics Through Use of Summary Feedback in Power Snatch Training

This study investigated kinematic and kinetic variable changes in the power snatch (PS) after 4 weeks of training and the use of summary feedback. Twenty-four collegiate football players participated as subjects in this study. The subjects were pretested for their 1-repetition maximum (1RM) and were separated into feedback (FG; n = 12) and control (CG; n = 12) groups. The FG was provided with augmented feedback (AF) during power snatch training sessions, which took place 3 times per week for 4 weeks. The AF is defined as information that is received in addition to what is naturally available. Variables measured include peak force (PF), peak power (PP), and several kinematic variables at 50, 70, and 90% of the subjects' pre-1RM. The PF was improved at 50% 1RM from 567 +/- 202 to 769 +/- 230 N, at 70% from 725 +/- 186 to 890 +/- 199 N, and at 90% from 822 +/- 197 to 1008 +/- 201 N in the FG (p <or= 0.05). The PP was increased at 50% 1RM from 2061 +/- 562 to 2538 +/- 498 W, at 70% from 2321 +/- 743 to 2754 +/- 629 W, and at 90% from 2076 +/- 437 to 2491 +/- 526 W in the FG (p <or= 0.05). Variables with respect to bar path kinematics improved significantly. No improvements in kinetics or kinematics were noted in the CG. These results indicate that both kinematic and kinetic variables improve through training and AF. Practitioners wishing to improve weightlifting performance should attempt to use evidence-based AF.

Changes in Bar Path Kinematics and Kinetics Through Use of Summary Feedback in Power Snatch Training

PURPOSE: The purpose of this study was to investigate the direction and magnitude of kinematic changes in bar path and kinetic variable changes in the power snatch (PS) after four weeks of supervised training and the use of summary feedback. METHODS: 24 collegiate football players who had a minimum of 18 months of prior experience in the PS participated as subjects in this study. The subjects were pre-tested for their one repetition maximum (1RM), pair matched, and randomly separated into a feedback vs. control group. The feedback group was provided with visual and verbal cues during power snatch training sessions, which took place three times per week for four weeks. Variables measured during data collection include pre and post peak force, peak power and several bar path kinematic variables through videography at 50, 70, and 90% of the subjects' pre-1RM. RESULTS: Peak force was improved at 50% of 1RM from 567 ± 202 to 769 ± 230 N, at 70% from 725 ± 186 to 890 ± 199 N and at 90% from 822 ± 197 to 1008 ± 201 N. Peak power was increased at 50% of 1RM from 2061 ± 562 to 2538 ± 498 watts, at 70% from 2321 ± 743 to 2754 ± 629 watts, and at 90% from 2076 ± 437 to 2491 ± 526 watts. Variables with respect to bar path kinematics were improved significantly. No improvements in kinetics or kinematics were noted in the control group.Figure: Caption not provided.CONCLUSIONS: These results indicate that both kinematic and kinetic variables improve through training and feedback. It is possible that persons beginning the PS exercise or coaches who provide instruction on the power snatch to beginning lifters should focus on proper bar path during the movement and the manner in which feedback is provided. This may result in force and power output to develop as technique improves even in more experienced lifters.