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The development of micro-robots based on bionic motion has garnered increasing attention with the advancement of bionic technology. These micro-robots can be employed in various tasks, such as military applications, disaster search and rescue, in vivo drug delivery, minimally invasive surgery, and tumor treatment. Robot joint motion is commonly achieved through actuators, which encompass motor, hydraulic, or pneumatic components that often carry excessive weight. To achieve the goal of miniaturizing robotic mechanisms, innovative actuators need to be developed. This study focuses on designing a four-limbed micro-robot that utilizes piezoelectric actuators. Automatic Dynamic Analysis of the Mechanical System is employed to investigate the kinematic aspects of the micro-robot’s motion, and finite element analysis is also used to obtain the resonant characteristics of the limbs actuated by piezoelectric bimorphs. The results indicate that the gait pattern of a piezoelectric robot changes according to the walking strategy and the robot dimension. The forward travel speed varies depending on the gait pattern, and adjustments in gait design can reduce the up/down oscillation and right/left offset. The robot’s travel speed increases with both trunk and limb length, although longer thigh and leg lengths might lead to greater offset and vertical oscillation. The resonant frequency and mode shapes change with the limb structure and affect the limb motion style. By adjusting the driving frequency of the bimorph actuators, the gait pattern can be manipulated. The information presented in this study contributes to a deeper understanding of micro-robot design.

In this paper we present a new approach for marker less human motion capture from conventional camera feeds. The aim of our study is to recover 3D positions of key points of the body that can serve for gait analysis. Our approach is based on foreground extraction, an articulated body model and particle filters. In order to be generic and simple, no restrictive dynamic modeling was used. A new modified particle-filtering algorithm was introduced. It is used efficiently to search the model configurations space. This new algorithm, which we call Interval Particle Filtering, reorganizes the configurations search space in an optimal deterministic way and proved to be efficient in tracking natural human movement. Results for human motion capture from a single camera are presented and compared to results obtained from a marker based system. The system proved to be able to track motion successfully even in partial occlusions and even outdoors.

Purpose: The purpose of this study was to assess the association of the knee flexion excursion to the vertical center-of-mass (COM) amplitude and to the lower-extremity muscle work during stance phase for subjects with knee osteoarthritis. Method: Twenty subjects scheduled for total knee replacement and 20 controls performed level walking during standard gait analysis. Dependent variables included stance-phase knee flexion excursion, vertical COM amplitude, and lower-extremity muscle work. Results: Compared to healthy control, subjects with knee osteoarthritis walked with significantly less stance-phase knee flexion and vertical COM excursion. Knee flexion excursion was found to have a strong positive correlation to vertical COM amplitude. The lower-extremity muscle work during single stance phase was found to have a moderate negative correlation to vertical COM amplitude. Conclusions: Osteoarthritis of the knee alters both the stance-phase knee flexion and vertical COM excursions. As these variables show a strong positive relation, efforts to restore stance-phase knee flexion based on the 3rd determinant of gait require a new justification.

Study design: Case study. Background: To date, there is little research that has examined the association of impairments at the hip with cumulative trauma syndromes of the hip. The purposes of this case report are to: (1) describe clinical outcomes for a patient with non-specific bilateral musculoskeletal hip pain associated with recreational walking, (2) explore the relationship between this patient's impairments and her cumulative trauma syndrome at the hip, and (3) integrate biomechanical analysis with this patient's clinical diagnosis. Case description: The patient was a 28-year-old female research assistant who reported anterior bilateral hip pain during recreational walking. After examination, the physical therapist diagnosed primary impairments of hip pain, limited hip flexion range of motion (ROM), and weakness of hip musculature, resulting in her ambulation limitations. Intervention consisted of a home exercise program (HEP) designed to strengthen the iliopsoas, gluteus maximus, and gluteus medius (specifically, the posterior portion), increase extensibility of the IT Band and medial hamstrings, and promote posterior glide of the proximal femur. The patient's HEP was the only intervention she received. There were follow-up telephone conversations, but no clinical re-examination for ten weeks. The patient performed the HEP a total of 41 days over the ten week period. Biomechanical gait analysis was performed pre- and post-intervention. Outcomes: Following intervention, the patient was pain-free during recreational walking, and passive hip flexion ROM and manual muscle testing (MMT) grades of hip musculature improved. Global score on the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) improved ten points. Motion analysis, force plate analysis, and electromyography (EMG) showed that maximum hip extension decreased, maximum hip flexion increased, maximum ground reaction force increased, activation of the gluteus maximus increased, while activation of the gluteus medius and tensor fascia latae (TFL) decreased following the intervention. Discussion: This patient's changes in muscle activity following a HEP appear largely consistent with improved symptoms based on theoretical descriptions of a common muscle imbalance (shortened and overactive TFL and weakness of the gluteus maximus and posterior portion of the gluteus medius), thought to contribute to increased femoral medial rotation.

Purpose: Differences in muscle activity have been observed between men and women in numerous lower extremity muscles in a variety of activities. These differences may be related to observed differences in the incidence of injuries between men and women. The purpose of this work is to determine if gender had an effect on the activity of the medial and lateral gastrocnemius muscles during the early part of the stance phase of gait. Method: An observational cohort study was set up using sixteen volunteers (9 men and 7 women, mean age = 27 years) with less than 5° of passive ankle-dorsiflexion range of motion. Maximum dorsiflexion, maximum knee flexion, stance time and EMG magnitude were measured for both men and women during early stance (heel strike to heel off). Results: EMG amplitude of the LG muscle in women was significantly higher than that of men. No significant differences were observed between men and women for maximum dorsiflexion, maximum knee flexion or stance time. Conclusions: A gender difference in gastrocnemius muscle EMG magnitude exists that is independent of knee and ankle kinematics and walking speed.

Walking with poles is one of the gait modification strategies for reducing external knee varus moments in people with medial knee osteoarthritis (OA). However, there are two types of pole techniques, Nordic walking (NW: pole back condition) and pole walking (PW: pole front condition). The purpose of this study was to investigate the differences in knee joint kinematics, and kinetics during level walking, and two types of walking with poles. A total of 22 subjects with a mean age of 21.2 years (SD: 1.3 years) participated. Three-dimensional gait analysis was conducted on level walking (LW), NW and PW. The first and second peaks of the knee kinematic and kinetic data and ground reaction forces were used. No significant differences were found between NW and PW in the knee kinematics and kinetics data. The second peak of the knee varus moment in NW and PW (0.34 and 0.33 Nm/kg, respectively) was significantly decreased compared to LW (0.42 Nm/kg, p < 0.01; Effect size = 0.70, p < 0.01; Effect size = 0.82). The first peak of the flexion moment in the knee during NW (1.2 Nm/kg) was significantly higher compared to LW (1.2 Nm/kg, p < 0.01; Effect size = 0.98). However, the present study could not clarify any different effect on the knee joint due to different instructions of the back pole and forward pole technique.

In this study, we simplified the analysis of kinetic gait data using pattern recognition. Gait patterns were studied in 42 spastic children with cerebral palsy (age range: 3 to 17 years old), and 24 age- and sex-matched children. Gait analysis was performed using the DynoGraphy (CDG) system (Infortronic, Holland). The foot enrollment and the role of the heel or forefoot were assessed to form the gaitline. The bipedal phase was examined using a cyclogram, which is a cyclic characteristic formed by the changing position of the application point of the resultant normal force on a vertical supporting horizontal plane during motion. Based on the pattern recognition, the gait patterns of the subjects could be classified into 4 different patterns in both the gaitline and the cyclogram. The classification of the gait was parallel to the clinical evaluation of cerebral palsy obtained based on Minear's classification of daily activity (p<0.05). The correlation between the gaitline and cyclogram was also highly significant (p<0.05). The results of this study suggest that an automated pattern recognition program might provide an additional method for comprehensive gait evaluation in children with cerebral palsy.

A markerless human gait analysis system using uncalibrated monocular video is developed. The background model is trained for extracting the subject silhouette, whether in static scene or dynamic scene, in each video frame. Generic 3D human model is manually fit to the subject silhouette in the first video frame. We propose the silhouette chamfer, which contains the chamfer distance of silhouette and region information, as one matching feature. This, combined dynamically with the model gradient, is used to search for the best fit between subject silhouette and 3D model. Finally, we use the discrete Kalman filter to predict and correct the pose of the walking subject in each video frame. We propose a quantitative measure that can be used to identify tracking faults automatically. Errors in the joint angle trajectories can then be corrected and the walking cycle is interpreted. Experiments have been carried out on video captured in static indoor as well as outdoor scenes.

Many physiological and anatomical changes occurring during the pregnancy period have been widely documented and reported in the literature. This study involved the participation of pregnant subjects, divided into their respective trimester periods, with post-partum normal subjects. Kinetics analyses were performed on each subject using the Peak Motus 2000 system, and comparison between the pregnant subjects in different trimester, and also the post-partum normal subjects, were conducted. The step width generally increases as the subject is progressing through her pregnancy periods. From the average, the step width increases from 0.168 m in the first trimester to 0.350 m in the third trimester, which is an increase of nearly 50%. It can be generally appreciated that the step width increases as the pregnancy period progresses. It shows that these increases may be attributed to the increase of the body weight of the subject as she gains more weight towards the end of her pregnancy.

Virtual proprioception represents a novel means of developing cortical reorganization of alternative strategies for hemiparetic gait. Fundamentals of the device are motor control plasticity, aftereffect, and visual-based biofeedback. Two wireless three-dimensional (3D) microelectromechanical systems (MEMS) accelerometers are placed on the femur (upper leg) of both the affected and unaffected limbs above the lateral epicondyle next to the knee joint. The acceleration data from the two wireless 3D MEMS accelerometers are fed back to the user in real time by visual output from a portable laptop PC. Given the virtual proprioception feedback, the user can then adjust the original gait while walking to an improved alternative gait strategy. First, hemiparetic gait is comprehensively discussed. The inherent roles of proprioception with locomotion and issues with traumatic brain injury are considered. Then, the technology advance of accelerometers and gait analysis is detailed. Virtual proprioception is tested and evaluated, while demonstrating the capacity to improve disparities in hemiparetic gait during real time.

A forward trunk lean sometimes occurs to compensate for quadriceps muscle weakness. Since muscle weakness in the lower extremities is commonly observed in the elderly, quadriceps weakness may trigger age-related postural change. The objective of this study was to ascertain the association between forward trunk lean during walking and musculoskeletal strength in females aged between 46 and 79 years. Musculoskeletal functions (range of joint motion, degree of kyphosis, muscle strength) and joint moments during walking were measured for 13 females. Subjects who showed greater joint moments during walking tended to lean more. Moderate association was seen between mean trunk angle during walking and knee extension moment (r = 0.535, p = 0.060). There was no statistically significant correlation between the strength of the quadriceps muscle and the mean trunk angle in walking subjects (r = 0.095, p = 0.758). These observations suggested that muscle weakness in the quadriceps is largely independent of leaning of the trunk for this sample of subjects. Other factors may change the posture to a stoop, such as severe thoracic kyphosis, poor balance control, or fear of falling.

Assessment of locomotion quality subsequent to neurological trauma, such as stroke or traumatic brain injury is imperative for the correct allocation of therapy dosage and strategy. In light of the limited amount of medical professionals in contrast with the rising number of people with neurological disorders; a new paradigm for addressing therapeutic strategies for neurological trauma is advocated. An important aspect for therapy of neuro-motor disorders is the characterization of gait. There are devices presently used for evaluating gait, such as EMG, optical sensors, electrogoniometers, metabolic energy expenditure devices, foot stride analyzers, and ground reaction force sensors. These devices have inherent issues, such as spatial constraints, line of sight requirements, and specialization requirements. A solution for improved autonomy of gait assessment is demonstrated by the use of fully wireless 3D MEMS accelerometers, which are light weight and minimally intrusive. To minimize specialization issues, the accelerometers may be positioned at a standard anatomical anchor. The role of traumatic brain injury with respect to gait dysfunction is addressed. Enclosed is the initial test and evaluation of a wireless 3D MEMS accelerometer for gait analysis. The gait analysis is conducted in outdoor conditions, while walking on a sidewalk.

The aim of the present study was to identify the phases of gait and the joints where the "ground reaction vector technique" (GRVT) can represent an acceptable alternative to the use of inverse dynamics (ID), when considering subjects with a lower-limb amputation. First, an analytical investigation of the ID of the three joints of the lower limb is given, distinguishing the gravitational, the inertial and the ground reaction contributions. The first two contributions require inertial parameters estimation; for this purpose, literature anthropometric data are typically used, both for the unimpaired and prosthetic limb, as accurate specific inertial parameters for the prosthetic limb are difficult to obtain from companies or require time consuming estimation. This assumption potentially leads to errors in the three-dimensional (3D) joint moment estimation. Second, the results of two case studies, a trans-femoral amputee with two different prostheses and a trans-tibial amputee, showed that the GRVT can explain the most part of the net joint moment for the ankle and the knee in the whole stance phase, and for the hip in the first part of the stance, leading to a similar clinical evaluation without any assumptions on inertial parameters.

The aim of this study is the objective assessment of gait abnormalities in diabetic patients and the quantification of the benefits of physical activity in improving gait quality. Patients were equipped with foot-switches and knee goniometers and were asked to walk at their natural pace for 2.5 min. A statistical gait analysis was performed extracting from hundreds of strides the "atypical" cycles, i.e., the cycles which do not show the usual sequence of gait phases (heel contact, flat foot contact, push off, swing), the duration of the heel contact phase, and the knee kinematics in the sagittal plane. A sample population of 27 non-neuropathic type 2 diabetic patients was examined before and after attending a light-intensity physical activity program that lasted for four months. A fuzzy classifier was used to assign a score to the gait abnormalities of each patient in baseline conditions and after the program completion. More than 50% of the subjects showed a significant reduction in their gait abnormalities and on average, the most frequent improvements were the reduction of atypical cycles and heel contact duration. Furthermore, we found that in basal conditions, the left side is more affected by gait abnormalities than the right (P < 0.003).

The proper allocation of a therapy strategy and dosage is fundamentally associated with the quantified evaluation of gait quality. Wireless accelerometer systems for the evaluation of quantified hemiplegic gait characteristics has been successfully applied in inherently autonomous environments through the consideration of the temporal domain of the gait acceleration waveform. The frequency domain has notable potential for identifying the quantified disparity of the affected leg and unaffected leg through the application of a tandem-activated wireless accelerometer system mounted to the lateral malleolus of each lower leg through an elastic band. The quantification of disparity for hemiplegic gait via the application of wireless accelerometers was applied in an outdoor environment, while walking on a sidewalk. In addition, the wireless accelerometers were tandem activated while the subject had achieved steady-state gait status, which mitigated the need to subjectively remove starting acceleration and stopping deceleration aspects of the gait cycle. Four predominant frequencies within the 0–5 Hz bandwidth demonstrated a considerable degree of accuracy and reliability. The organization of the four predominant frequencies for both affected leg and unaffected leg were found to be disparate in a statistically significant manner, implicating a disparity of the rhythmicity respective of the affected leg in contrast to the unaffected leg in hemiplegic gait. These preliminary findings may advance gait quantification techniques, which may improve the efficacy of gait rehabilitation therapy. Enclosed are the initial test and evaluation of a tandem-activated wireless accelerometer system using the frequency domain for ascertaining a quantified disparity of hemiplegic gait.

The necessity for developing advanced prostheses are apparent in light of projections that the forecast for the number of people enduring amputation will double by the year 2050. The transtibial powered prosthesis that enables positive mechanical work about the ankle during the powered plantar flexion aspect of stance phase constitutes a paradigm shift in available transtibial prostheses. The objective of the review is to advocate the state of the art regarding the transtibial powered prosthesis. The historic origins of the prosthesis and motivations for amputation are clarified. The phases of gait and the compensatory mechanisms and asymmetries inherent with passive transtibial prostheses are described. The three general classes of transtibial prosthesis (passive, energy storage and return and powered prostheses) are defined. Subsystems that are integral to the powered prosthesis are explained, such as the series elastic actuator and control architecture. Gait analysis systems and their role for the test and evaluation of energy storage and return and powered prostheses are demonstrated. Future advanced concepts; such as the integration of titin into novel muscle models that account for force enhancement and force depression including their implications for cutting edge bio-inspired actuators are elucidated. The review accounts for the evolution of the prosthetic device with regards to the scope of transtibial amputation and assesses the current state-of-the-art.

The foot plays an important role as it is the only connection that the human body has with the floor when walking, running, etc. The two main techniques commonly used to study the lower limb in biomechanics are gait analysis and plantar pressure measurements. However, they require different settings: One requires barefoot experimentation and the other requires the subject to be shod. The method proposed in this paper attempts to solve this problem by designing shoes that can mimic both conditions. This allows the analysis of both approaches simultaneously and therefore provides valuable inputs for the development of a well validated model of the foot.

The gait analysis of subjects with short and non-uniform gait is difficult using the common commercial force platforms. The present work consists in the design, based on finite element method (FEM) analysis, of a force platform of two different dimensions (0.40 × 0.40 m and 0.80 × 0.40 m) considering static and dynamic simulation of their behavior. The aim of this project is to improve, with a simple, low cost and flexible structure, the instrumentation available for the gait analysis of children, neurologic patients and in general the most common clinical cases. The applicability of gait analysis to children, neurologic patients ECC can be improved by the flexibility of force platforms without losing the performance provided by traditional force platforms (e.g., for postural analysis).

Human gait is the identity of a person's style and quality of life. Reliable cognition of gait properties over time, continuous monitoring, accuracy of evaluation, and proper analysis of human gait characteristics have demonstrated their importance not only in clinical and medical studies, but also in the field of sports, rehabilitation, training, and robotics research. Focusing on walking gait, this study presents an overview on gait mechanisms, common technologies used in gait analysis, and importance of this particular field of research. Firstly, available technologies that involved in gait analysis are briefly introduced in this paper by concentrating on the usability and limitations of the systems. Secondly, key gait parameters and motion characteristics are elucidated from four angles of views; one: gait phases and gait properties; two: center of mass and center of pressure (CoM-CoP) tracking profile; three: Ground Reaction Force (GRF) and impact, and four: muscle activation. Thirdly, the study focuses on the clinical observations of gait patterns in diagnosing gait abnormalities of impaired patients. The presentation also shows the importance of gait analysis in sports to improve performance as well as to avoid risk of injuries of sports personnel. Significance of gait analysis in robotic research is also illustrated in this part where the study focuses on robot assisted systems and its possible applicability in clinical rehabilitation and sports training.

The present study aimed to investigate the potential clinical value of three-dimensional gait analysis (3D-GA) system in evaluating ankylosing spondylitis (AS). Thirty-one patients with AS from September 2010 to August 2011, with 32 involved and 30 uninvolved lower limbs, were enrolled. Data of spatio-temporal parameters (step and stride length, velocity and cadence), time parameters (stance, single stance, double stance and swing phases) and kinematics parameters associated with spinal mobility (spinal lateral bending, spinal forward bending and spinal rotation) were analyzed by 3D-GA system, as well as curative effects of biologic therapy. Compared with normal values, AS patients showed decreased step and stride length ($p<0.05$), increased cadence, longer swing and single stance phases ($p<0.01$) and shorter stance and double stance phases ($p<0.05$) in uninvolved lower limbs. In AS patients, reduced step length, stride length, velocity and cadence, shorter swing and single stance phases, longer stance and double stance phases ($p<0.05$), increased lateral bending angle and decreased spinal rotation ($p<0.01$) were detected by 3D-GA in involved lower limbs compared with uninvolved ones. In the 16 patients with decreased levels of ESR and CRP and improved ASAS scores after biology therapy, increased step length, stride length, velocity and cadence of the involved lower limbs were detected by 3D-GA ($p<0.05$), as well as improved spinal mobility ($p<0.05$). Hence, we concluded that 3D-GA has great potential value of clinical application for assessing and monitoring AS.