Support Leg Research Articles

Practical whole-body elasto-geometric calibration of a humanoid robot: Application to the TALOS robot

The whole-body elasto-geometrical calibration of humanoid robots is critical particularly for their control and accurate simulation. However, it is often not considered probably since it is a nontrivial task due to the mechanical complexity and inherent constraints of anthropomorphic structures. Also, humanoid robots have to sustain great efforts on their support legs, leading to link and joint being deformed, and are prone to auto-collision. Thus, elastic parameters have to be factored in addition to the geometric ones and to improve the precision of the pose of all robot segments. This is much more cumbersome and time consuming than the classical calibration of serial manipulators that deals solely with the estimation of the pose of the end-effector. Finally, due to the complexity of the task, a manual intervention in several steps of the calibration is no longer possible and a thorough automation of the approach is needed. Therefore, we propose to use a stereophotogrammetric system along with embedded joint torque sensors to calibrate the pose of all robot links with a fully automatic procedure. The generation of the minimal set of optimal calibration postures is based on a new iterative optimization process that leads to a stable maximum of an observability index. Then full set of geometrical parameters but also joint and base elastic parameters were calibrated using a single least-square optimization program. The proposed method was validated on a TALOS humanoid robot allowing to obtain an accurate whole-body calibration in less than 10 min. The proposed approach was cross-validated experimentally and showed an average RMS error of the tracked markers of 2.2 mm.

Research on obstacle performance and tipping stability of a novel wheel–leg deformation mechanism

Abstract. A new type of wheel–leg deformation mechanism, based on an electromagnetic clutch and gear rack transmission mechanism, is designed. This mechanism has a compact structure and simple operation, which can roll on wheels and surmount obstacles with a support leg. Firstly, the walking model is established to study the kinematics characteristics of the mechanism. The alternation of the support legs does not affect smooth obstacle crossing, but will cause the step change of the angular velocity of the centroid of the main body. Secondly, the obstacle-surmounting performance of roll-over mode and obstacle-crossing mode using support legs is analyzed. For roll-over mode, the maximum climbing height is 87.36 mm. For obstacle-crossing mode using support legs, the maximum climbing height is the maximum extension length of the support leg. According to the climbing height, the switching criteria of different climbing modes are obtained. In addition, the rolling angle of the main body has a greater impact on the support force and driving torque, while the contact angle between the legs and the ground has a small impact. Finally, the tipping stability and anti-interference ability of the wheel–leg deformation mechanism is evaluated using the stability cone method.

ПОДЗАРЯДКА БЕСПИЛОТНЫХ ЛЕТАТЕЛЬНЫХ АППАРАТОВ С ВЕРТИКАЛЬНЫМ ВЗЛЕТОМ-ПОСАДКОЙ НА КОНТАКТНЫХ ПЛАТФОРМАХ С АДАПТИРУЕМОЙ ШИРИНОЙ КОНТАКТНЫХ ПОЛОС

Relevance The article describes one of the modifications of ground charging platforms for electric unmanned aerial vehicles (UAVs) with vertical takeoff and landing (VTOL). It belongs to the class of charging platforms with open pads. The previously described platforms with coplanar band parallel electrodes (CBPE) have multiple parallel strip electrodes with alternating polarity, isolated from each other by narrow dielectric separators. The corresponding on-board electrodes of the multi-rotor UAV with a symmetrical frame are proposed to be arranged at the ends of the support legs under the bearing beams of the engine-propeller groups. Thus, the contact points for the quadrocopter will be at the vertices of the square. With certain geometric relationships between the width of the ground electrodes and the interelectrode distances of the on-board electrodes for any UAV position on the platform, almost 100% different polarities of the on-board electrodes is ensured after landing, and as a consequence, the ability to bring the voltage from the ground DC source to the on-board battery charger. The advantages of such platforms are: relative simplicity of design, independence of maintenance from the accuracy of landing and the ability to charge several UAVs at the same time. However, UAVs may have various sizes and therefore various interelectrode distances, which may violate the condition of different polarities of on-board electrodes after landing. Therefore, it is important to find a solution in which reliable service of the CBPE platform for UAVs of different sizes is possible. Aim of research Finding a technical solution for adaptive band width change of a CBPE landing platform that allows charging UAVs of different sizes. Research methods Prototyping the adaptable CBPE platform and pilot study of its operation. Results The proposed modification of the platform consists in arranging the switching of bands in such a way that alternating groups of bands of one polarity are formed. Bands can be grouped into 1, 2, 3, 4, etc. Such a group works as a single band of appropriate width, which can be changed discretely. In this way, it is possible to adapt the width of the platform stripes depending on the type of vehicle coming for landing. An experimental landing platform for multicopters and a variant of implementing a commuting device for platform adaptive configuration are described.

PESQUISA SOBRE OS PRINCIPAIS MÉTODOS DE TREINO DE FORÇA DO CORE EM VELOCISTAS

ABSTRACT Introduction With the development of increasingly competitive sports, coaches began experimenting with new methods for training athletes. Although among the most explored training methods is core strength training, a set of muscle groups that stabilize the trunk and hips, there are few studies on the effectiveness of this training dedicated to sprinters. Objective This paper investigates the training method of sprinters based on core strength training, studying the method and its influence on athletes’ performance. Methods Sixteen athletes with similar technical levels and physical fitness were selected, and professional coaches were invited to test the training samples. The athletes were randomly assigned to the experimental and control group (8 in each). The experimental group received core strength training for eight weeks, while the control group received general training. Results Off-core training affected the ankle joint angle of the support leg and the ankle joint angle of the swing leg (P < 0.01). After eight weeks of training, the performance of both groups improved without considerable differences. The high jump results of the athletes in the experimental group also improved compared to the previous training. Conclusion The physical function of athletes can be improved through core strength training to improve the sprinters’ competitive level and technical ability. Level of evidence II; Therapeutic studies - investigation of treatment outcomes.

Optimization of an Active Leveling Scheme for a Short-Range Gravity Experiment

At Cal Poly Humboldt, undergraduate researchers and faculty have constructed a torsion-pendulum experiment that seeks to measure gravitational interactions below test mass separations of 100 microns. The aim of this experiment is to look for deviations in the weak equivalence principle (WEP) and inverse-square law (ISL). The scale at which this experiment operates is within an untested range at the submillimeter scale. This apparatus’s torsion pendulum consists of equal masses with differing materials arranged as a composition dipole. The twist of this configuration is measured as an attractor mass oscillates in a parallel-plate arrangement nearby. The oscillation creates a time-dependent torque on the pendulum which can be studied for deviations in the WEP and ISL. At present, an active leveling scheme has been implemented to mediate the apparatus’s long-term tilt variations. This scheme has been optimized through the use of a power supply and proportional-integral-derivative (PID) loop that mitigates the variations in tilt by applying a voltage to a resistor attached to one of the apparatus legs. The applied voltage causes thermal expansion of the apparatus leg support structure, thus correcting and modulating the tilt of this experiment.

CARACTERÍSTICAS DA FORÇA MUSCULAR ISOCINÉTICA NA ARTICULAÇÃO DO JOELHO EM ATLETAS DE SALTO EM ALTURA

ABSTRACT Introduction: Vertical jump is inherent to the practice of high jump and demands great capacity of force generation and work of the knee muscles, especially the quadriceps muscle. Due to this demand, imbalances between the extensor and flexor knee muscles may be present, leading to an overload of the musculotendinous structures of the knee joint. Therefore, it is necessary to establish the characteristics of isokinetic muscle strength in the knee joint of these athletes. Objective: This study aimed to analyze the biomechanical properties of the knee flexor and extensor muscles in high jump athletes. Methods: Ten high jumpers volunteered for the experiment. They were divided into experimental and control groups. Both groups performed basic strength training. The experimental group added isokinetic knee muscle training based on this training. Statistical analyses were performed on the training data of the two groups of athletes using relevant mathematical statistics. Results: The high jump consists of four phases being respectively the approach run, the jump itself (impulsion, elevation, transposition), and the fall. The strength of the ankle joint dorsiflexion and plantar flexors was significantly increased in the experimental group of athletes. In contrast, the strength of the plantar flexors in the control group was significantly increased. Statistical differences were found between the two groups (P<0.05). Conclusion: The isokinetic knee joint strength training mode can improve the leg support strength of jumpers. This paper suggests that high jump athletes can further adopt this lower limb strength training method. Level of evidence II; Therapeutic studies - investigation of treatment outcomes.

Hip arthroplasty using the cartilaginous part of the greater trochanter in the treatment of the sequelae of epiphysal osteomyelitis in children

BACKGROUND: Alternative methods of hip arthroplasty as a result of the complete destruction of the epiphysis and femoral neck using the preserved part of the apophysis of this segment are not widely reported, which may be useful for specialists who are faced with the choice of providing such assistance.
 AIM: To present the long-term results of treating children with the hip joint reconstruction method developed in the clinic using trochanteric arthroplasty by utilizing the intact cartilaginous part of the greater trochanter apophysis for the treatment of defects resulting from osteolysis of the femoral head and neck after epiphyseal osteomyelitis.
 MATERIALS AND METHODS: The results of the surgical treatment of seven children (two of them had a bilateral process) who underwent reconstruction of nine hip joints according to the proposed method were analyzed. The procedures were performed at the age of 210 years. The intervention involved the surgical preparation of the acetabulum with repositioning of the greater trochanter after proximal angulation osteotomy of the hip at the metadiaphyseal level. In four patients with a unilateral process, Salter innominate osteotomy was additionally performed in one or two stages. In five patients with a unilateral process with further growth, limb lengthening was performed. The efficiency index was evaluated using both anatomical and functional results. In a bilateral process, the assessment considered the function of the worst operated joints.
 RESULTS: In six children, good and, in one child with a bilateral process, satisfactory long-term clinical and functional results were obtained (assessed 1020 years after the first reconstructive surgery). All of them had restored limb support without pain, with a sufficient range of motion. The method was organ-preserving, which enabled an opportunity for walking, and an anatomically favorable situation for further arthroplasty has been created, the timing of which has been postponed to a mature period.
 CONCLUSIONS: The method developed in the clinic for the surgical use of the greater trochanter for the reconstruction of the hip joint after infectious osteolysis of the head and neck of the femur is effective, allowing for a long time to maintain leg support using the patients tissues.

Online gait generator for lower limb exoskeleton robots: Suitable for level ground, slopes, stairs, and obstacle avoidance

The development of lower limb exoskeletons has seen significant interest in recent times. Two types of them are more used that cover two types of needs: gait rehabilitation and human locomotion assistance. An essential subject in controlling the latter kind is trajectory generation, in which there are still challenges. For online controlling of the exoskeleton, gait parameters must have the ability to change at any moment during walking, taking into account human intention and particular conditions. In this paper, an online gait generation method is provided that is suitable for different walking modes. For this purpose, three trajectory generator blocks are proposed. The first block is for the center of mass (CoM) in the double support phase, where the trajectory is generated to make the patient feel more comfortable. The second block is for the support leg in the single support phase. The trajectory is generated using the center of pressure (CoP) criterion to secure backward balance and reduce the forces applied to the arms. The last block is for the swing leg in the single support phase, where a cost function is proposed to minimize the torques of the motors. The performance analysis of the proposed trajectory generator blocks was evaluated, and walking patterns were examined via simulations. Finally, three experimental tests were implemented with a healthy subject wearing Exoped® exoskeleton on level-ground with an obstacle, and stairs.

Single Leg Posture of a Professional Soccer Player with Iliopsoas Injury and the Relationship Between Trunk and Pelvis Posture and Torque of the Hip Flexor

BACKGROUND: The purpose of this study was to provide data on postural characteristics and the low torque of the hip flexor observed after an iliopsoas injury in a professional soccer player. CASE PRESENTATION: The patient was a male professional soccer player. He was diagnosed with an injury to the left iliopsoas. After completing rehabilitation, he complained of decreased performance that he described as “not being able to take one more step.” OUTCOME: In terms of single-leg standing posture, different phenomena were observed between the right and left legs in the posture angles of the trunk and pelvis. The low torque was observed in the left hip flexor. DISCUSSION: We hypothesized that the low torque of the left hip flexor affected the left leg support and soccer performance. JOSPT Cases 2022;2(4):234–239. doi:10.2519/josptcases.2022.11053

Wave-like character of rock pressure in a longwall face

Introduction. Coal seam extraction causes rock mass displacement, which often leads to negative consequences. It is important to take into account the process patterns within the undermined rock mass to reduce the negative effect. Intensifi ed mining operations, increased lengths of faces and extraction panels, and increased per face output inevitably cause changes in all geomechanical processes in the face. Research theory. When designing and developing the working area, it is important to examine and forecast the geomechanical situation, as well as take into account the parameters and elements of the displacement processes caused by coal seam mining. The research objective is to determine the infl uence patterns in the rock seam that exerts pressure on mine support. The article presents the results of pressure area construction when mining longwall faces in gently sloping coal seams. Methods of research. Rock pressure on a power support unit was monitored based on pressure readings in the legs using Marko company data. The Surfer software product was used to build the pressure area and its profi les. The pressure area is obtained by converting the fl uid pressure in power support legs into rock pressure. The variation of the longwall support pressure during coal seam mining is shown. Results and analysis. The paper proposes an algorithm for calculating the thickness of the seam that exerts pressure on the longwall face support. The algorithm considers its wave-like changes along the length of the panel. The thickness of rocks exerting pressure on the support is up to 10 seam thicknesses. Conclusions. The height of the pressure arch generally coincides with the parameters for the disordered collapse zone. It is 4–8 times as big as the thickness of the extracted seam. The process of roof collapse and displacement a longwall face is wave-like. The height of the pressure arch can be determined using a sinusoid and the concepts of rock mass structuring according to the algorithm presented in this paper

Adaptive robust force control of an underactuated walking lower limb hydraulic exoskeleton

This paper presents an adaptive robust interaction force control algorithm for an underactuated walking lower limb hydraulic exoskeleton. In order to deal with the problem of passive joints (less of control inputs), holonomic constraints from the wearer are considered in system dynamics, which help transform the underactuated exoskeleton dynamics into fully actuated dynamics in Cartesian space. Based on the established dynamic model, adaptive robust interaction force controllers are presented both for the phase of double leg support and single leg support to effectively deal with multiple walking phases, negative effect of high-order nonlinearities of hydraulic systems as well as various model uncertainties and external disturbances. An additional torque allocation method is proposed to deal with the over-actuated characteristic in double leg support phase. Comparative simulations are carried out. The results demonstrate that the proposed force controller can achieve precision and strong robust interaction force control performance to load change and variation of the human trajectory.

Does 8Weeks of Integrated Functional Core and Plyometric Training Improve Postural Control Performance in Young Rhythmic Gymnasts?

It has been suggested that core stability and plyometric training(CPT) can enhance athletes' postural control. Nevertheless, the effects of an integrated core and plyometric training program on rhythmic gymnastics (RG) performance are unclear. This study aimed to evaluate the effects of an integrated functional CPT program on young rhythmics gymnasts' postural performance. A sample of 44 young female rhythmic gymnasts from a competitive team (age = 10.5 ± 1.8years) participated in the study. The subjects were randomly divided into a control group and an experimental group. Pre- and posttest design was used. Postural control was assessed using single-leg stance tests and RG-specific balances over a force platform and evaluated by expert RG judges. The experimental group (n = 23) completed an 8-week functional CPT program based on RG technical requirements. Meanwhile, the control group (n = 21) received their usual training sessions. A mixed model of analysis of variance was applied to evaluate the effects of an intrasubject factor and an intersubject factor on each of the dependent variables. After 8weeks, the experimental group obtained significant better results in some variables of the right support leg with eyes open and left support leg with eyes open single-leg support (p < .01), improvements were also found in some specific RG balances: Arabesque measured on the force platform (p < .01) and the side leg with help balance scored by the judges (p < .01). In conclusion, an integrated functional CPT program improved postural control in young rhythmic gymnasts. Coaches should consider using this CPT to improve RG performance.

A biomechanical comparison of superior ramus plating versus intramedullary screw fixation for unstable lateral compression pelvic ring injuries,,,

IntroductionManagement of the anterior component of unstable lateral compression (LC) pelvic ring injuries remains controversial. Common internal fixation options include plating and superior pubic ramus screws. These constructs have been evaluated in anterior-posterior compression (APC) fracture patterns, but no study has compared the two for unstable LC patterns, which is the purpose of this study. MethodsA rotationally unstable LC pelvic ring injury was modeled in 10 fresh frozen cadaver specimens by creating a complete sacral fracture, disruption of posterior ligaments, and ipsilateral superior and inferior rami osteotomies. All specimens were repaired posteriorly with two fully threaded 7 mm cannulated transiliac-transsacral screws through the S1 and S2 corridors. The superior ramus was repaired with either a 3.5 mm pelvic reconstruction plate (n = 5) or a bicortical 5.5 mm cannulated retrograde superior ramus screw (n = 5). Specimens were loaded axially in single leg support for 1000 cycles at 400 N followed by an additional 3 cycles at 800 N. Displacement and angulation of the superior and inferior rami osteotomies were measured with a three-dimensional (3D) motion tracker. The two fixation methods were then compared with Mann-Whitney U-Tests. ResultsRetrograde superior ramus screw fixation had lower average displacement and angulation than plate fixation in all categories, with the motion at the inferior ramus at 800 N of loading showing a statistically significant difference in angulation. ConclusionAlthough management of the anterior ring in unstable LC injuries remains controversial, indications for fixation are becoming more defined over time. In this study, the 5.5 mm cannulated retrograde superior ramus screw significantly outperformed the 3.5 mm reconstruction plate in angulation of the inferior ramus fracture at 800 N. No other significance was found, however the ramus screw demonstrated lower average displacements and angulations in all categories for both the inferior and superior ramus fractures.

P114. Cervical decompression surgery improves postural stability and gait velocity in patients with cervical spondylotic myelopathy

<h3>BACKGROUND CONTEXT</h3> Cervical spondylotic myelopathy (CSM) is a progressive degenerative condition that can lead to functional deficits and gait instability. Biomechanical changes to a patient's dynamic and postural stability after decompressive surgery are poorly understood. <h3>PURPOSE</h3> The aim of this study was to determine how spatiotemporal gait parameters, postural stability and dynamic stability change after decompressive surgery in patients with CSM. <h3>STUDY DESIGN/SETTING</h3> Prospective cohort study. <h3>PATIENT SAMPLE</h3> Patients aged 40 to 80 years old with Nurick grade 2 or 3 CSM spanning one to four levels undergoing decompressive surgery were prospectively enrolled in this study. Decompression surgery was defined as decompression with or without fusion of the cervical vertebra. Exclusion criteria included: patients who could not ambulate independently, had a history of surgery within 6 months of initial gait evaluation or gait altering lower extremity surgery. <h3>OUTCOME MEASURES</h3> A tilted ellipse area with bidirectional variance was used to assess postural stability metrics. Generated ground reaction forces (GRF) and variation in bidirectional center of pressure (CoP) motion were recorded and represented in an ellipse area around patient-generated CoP. Additionally, the analysis consisted of the examination of the following spatiotemporal gait parameters: stride length (distance over the ground between ipsilateral heel strikes), cadence (steps per minute), velocity (the speed of the patient's center of mass (CoM), step width (distance between two feet during period of double support), toe-off (percentage of the pre-swing portion of the gait cycle where ipsilateral limb leaves the ground and initializes single leg support) and double support (percentage of gait cycle spent with two feet on the ground). Dynamic stability of gait is inversely proportional to angular momentum regulation, where greater stability is shown by minimizing angular momentum excursion. Angular momentum was calculated using exported joint centers and joint angles, where each segment's angular momentum was computed as the sum of its local angular momentum and the angular momentum of the segment about the whole-body CoM, which was taken to be the sum of 15 body segments. <h3>METHODS</h3> A total of 47 subjects, including 23 Nurick grade 2 or 3 CSM patients and 24 controls, were included. Measurements were taken at baseline in both cohorts and then at 3- and 6-months following decompression in the CSM cohort. Standing balance trials were performed on a single force plate, and walking trials were conducted at a self-selected pace over a 15m runway and a series of five force plates. All trials were recorded with 3D motion analysis cameras, and gait modeling software was utilized. Repeated measures ANOVA was used to compare measurements at three timepoints, followed by paired t-tests. The significance value was set at P<0.05. <h3>RESULTS</h3> Patients with CSM had a significant increase in gait velocity postoperatively at 6 months (0.948 ± 0.248 m/s) compared to baseline (0.852 ± 0.257 m/s) (P = 0.008). CSM patients had a significant decrease in tilted ellipse area from baseline (979.8 ± 856.7 mm2) to 6 months (598.0 ± 391.1 mm2) (P = 0.018) postoperatively. There was no significant difference in angular momentum excursion between baseline and postoperative measurements. <h3>CONCLUSIONS</h3> Decompressive surgery in CSM patients was associated with significant improvement in gait velocity and postural stability. However, there was no significant change in dynamic stability throughout the study period. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

Field and numerical modelling on the stability of underground strata in longwall workings

The longwall method is one of the feasible and efficient underground mining methods for greater depth of workings. Recently, Singareni Collieries Company Limited (SCCL), the largest coal-producing government company in the Southern part of India, has deployed a high capacity (2 × 1152T capacity) power support system in its Adriyala Longwall Project (ALP) at a depth of 375 m. There was a concern about the stability of the longwall workings and the protective pillars. Thus, research work was carried out with the geotechnical instruments and numerical modelling tools to analyze the stability while retreating the longwall panels. The outcomes revealed that the convergence in the gate roads increased with the longwall face advancement and the area of exposure. The pressure of the powered support legs on the dip side was less than the rise side legs, which implies a stable roof condition over the longwall face. An abutment zone was identified ahead of the line of extraction up to 10–25 m and presumed from the Factor of Safety (FoS) criterion that within this zone, the longwall pillar possibly will be of better stability at every stage of extraction. The results obtained from this study would be helpful for the mining engineers to understand the behaviour of underground strata in longwall workings.

Detection thresholds for electrostimulation combined with robotic leg support in sub-acute stroke patients.

Stroke is one of the leading causes of disability in adults in the European Union. It often leads to motor impairments, such as a hemiparetic lower extremity. Research indicates that early task-specific and intensive training promotes neuroplasticity and leads to recovery and/or compensation. One way to provide intensive training early after a stroke is via robot-supported training. A rehabilitation robot was designed by Life Science Robotics (Aalborg, Denmark) that can provide continuous repetitive movements of the hip, knee, and/or ankle in e.g., a lying position. In order to emphasize active contribution by the patient, actively triggered electrical stimulation (via muscle activation) can be combined with robotic assistance. The current study aims to compare different threshold estimation methods for detection of movement intention from muscle activity for actively triggered electrical stimulation during robot-supported leg movement in stroke patients. Three sub-acute stroke patients were included for a single measurement session. They performed knee extension and/or ankle dorsal flexion with four different threshold estimation methods to assess the intention detection threshold to initiate electrostimulation. The thresholds were based on the resting level of muscle activity (of m. rectus femoris or m. tibialis anterior) plus two or three times the standard deviation of the average resting value, or the resting level plus 5% or 10% of the peak muscle activity during a maximal voluntary contraction. The results showed that the method based on the resting muscle activity plus two times the standard deviation was the most stable across the three included stroke patients. This method had a detection success rate of 86.7% and was experienced as moderately comfortable. In conclusion, performing knee extension and/or ankle dorsal flexion with electromyography triggered electrostimulation is feasible in sub-acute stroke patients. Muscle activity-triggered electrostimulation combined with robotic support based on a threshold of resting levels plus two times the standard deviation seems to detect movement initiation most consistently in this small sample of sub-acute stroke patients.

Biomechanical Characteristics of the Support Leg During Side-Foot Kicking in Soccer Players With Chronic Ankle Instability

Background:Chronic ankle instability (CAI) in soccer players can increase the risk of recurrent ankle varus sprains and damage the articular surface of the ankle joint, thus increasing the risk of osteoarthritis. It is important to understand the biomechanical characteristics of the support leg during kicking in soccer players with CAI.Purpose/Hypothesis:The purpose of this study was to clarify the kinematics of the kicking motion of soccer players with CAI. It was hypothesized that at the point before ball contact when the support leg makes flat-foot contact with the ground, soccer players with CAI will land with ankle inversion in the support leg during a side-foot kick compared with players without CAI.Study Design:Controlled laboratory study.Methods:The study cohort included 19 male college soccer players (mean age, 20.5 ± 0.9 years) with greater than 8 years of soccer experience who were recruited from August 2019 to March 2020. Of these athletes, 10 had CAI and 9 had no CAI in the support leg, as diagnosed according to the Cumberland Ankle Instability Tool. Kinematic data for the trunk, hip, knee, and foot of the support leg during a side-foot kick were obtained using a 3-dimensional, motion-analysis system. The Mann-Whitney U test or Student t test was selected to identify differences in variables between the CAI and non-CAI groups.Results:There were no significant differences in physical characteristics between the CAI and non-CAI groups. At the point when the support leg made flat-foot contact with the ground, the players with CAI had more eversion of the hindfoot with respect to the tibia (-28.3° ± 12.1° vs -13.9° ± 14.2°; P = .03), a more varus alignment of the knee (26.0° ± 10.7° vs 13.7° ± 10.5°; P = .03), and a lower arch height index (0.210 ± 0.161 vs 0.233 ± 0.214; P = .046) compared with non-CAI players.Conclusion:Significant differences between players with and without CAI were seen in the support leg kinematics at flat-foot contact with the ground during the kicking cycle.Clinical Relevance:The biomechanical alignment of the support leg during a side-foot kick in players with CAI may reflect a subconscious attempt to avoid inversion of the foot and further ankle sprains.

Portable solar billboard

Public bulletin boards are widely used in various public places, but due to the large size of the billboards, it is not easy to carry, and the traditional billboards are integrated, when the billboards need to be transferred, the limited storage space of the vehicle needs to be occupied It is extremely inconvenient, and at night, the traditional bulletin boards need to install additional light sources to illuminate them, which greatly increases energy consumption. Based on this paper designed a new structure of the bulletin board, this structure can make the bulletin board when not in use completely folded up and easy to carry, and in use can be completely unfolded and in the bottom of the added retractable support leg structure can be placed anywhere, and according to the terrain or human will to adjust the height. A solar panel is placed on the top of the bulletin board, which can store solar energy during the day and supply energy to the LED lights on the top at night for lighting, which saves energy and is very environmentally friendly.

Model of the supporting leg of an anthropomorphous robot or exoskeleton with two movable links taking into account the dynamics of the electric drive. Power engineering: research, equipment, technology

Currently, the direction associated with the development of exoskeletons and anthropomorphic robots is experiencing rapid growth due to the increase in the computing power of microprocessors and the breakthrough development of the theory of control of complex systems, including electromechanical systems that simulate the biomechanics of the human musculoskeletal system. This paper presents a controlled mechatronic robotic model of the support leg of an anthropomorphic robot or exoskeleton with two moving links.GOAL. Mathematical modeling of the dynamics of the supporting leg of an exoskeleton or an anthropomorphic mechanism in the form of two moving links.METHODS. The main difference between the model presented in this study and those created earlier is the use of angles counted between links corresponding to the case of real operation of electric drives. To achieve the goal of the work, the methods of robotics, mathematical modeling, mechatronics, theoretical mechanics, the study of systems of ordinary differential equations, control theory, empirical data for the human musculoskeletal system were applied.RESULTS. For the model of the mechanism, a system of Lagrange equations of the second kind is written, direct and inverse problems of dynamics are solved for a given program control of the motion of a mechatronic robotic system. The results are presented graphically and as an animated visualization of the movement of the links. Calculations were carried out both without taking into account the dynamics of electric drives, and taking into account the rotation of the rotors of electric motors. It has been established that the influence of the dynamics of the rotor of the electric motor on the mechanism is significant.CONCLUSION. The developed methods for setting the program movement of the supporting leg of an exoskeleton or an anthropomorphic robot made it possible to solve direct and inverse problems of dynamics and establish the need to take into account the rotating rotor of an electric motor.

Interactions between rearward-facing child restraint systems and the front row seatback in frontal impact sled tests

Objective Some child restraint system (CRS) manufacturers specify a minimum distance between the CRS and the seatback, whereas others require that the CRS may contact the seatback but cannot be “braced”; however, few studies have investigated these interactions. Therefore, the aim was to investigate the interactions between the front row seat and rearward-facing CRS models with and without a support leg during frontal crashes. Methods Sled tests using the FMVSS 213 frontal crash pulse were performed with the Q1.5 and Q3 anthropomorphic test devices (ATDs) seated in rearward-facing infant and convertible CRS models, respectively. A front row vehicle seat was in front of the test bench in three track positions: brace, touch and gap. For the touch condition, the front row seat was translated aftward until the seatback contacted the CRS. For the brace condition, the front row seat was translated 20 mm aftward. For the gap condition, the front row seat was translated 50 mm forward. Each condition was tested with and without the support leg of the CRS. Results The tests with a support leg were associated with significantly (p = 0.007) lower resultant linear head acceleration 3 ms clip compared to the tests without a support leg, but the reduction of head injury criterion 15 ms (HIC15) was not significant (p = 0.057). The Q1.5 ATD in the rearward-facing infant CRS with a support leg had the lowest injury metrics for the touch and gap conditions, whereas the Q3 in the rearward-facing convertible CRS had the lowest head injury metrics for the brace condition. Conclusions The use of a support leg provided a clear benefit in terms of reducing head injury metrics for the Q1.5 in the rearward-facing infant CRS, especially for the touch and gap conditions. The rearward-facing convertible CRS in the current study appears to benefit from being braced against the front row seat. However, further tests are required to allow further statistical comparisons and determine if these preliminary findings extend to other rearward-facing CRS models.