Sharif Digital Repository

Background: Muscle synergy is the leading hypothesis on how the central nervous system coordinates limb functions. Cerebral palsy (CP) patients utilize fewer synergies, and are believed to have a simpler neuromuscular control. This study was undertaken to determine whether consistent muscle synergies are recruited during ambulation in cerebral palsy crouch gait and how the muscles contribute to such synergies. Methods: Ten ambulatory CP patients were recruited. All walked with crouch gait. sEMG data were collected from 14 lower limb muscles during gait analysis. Non-negative matrix factorization method was utilized to extract muscle synergies. Results and significance: A total of five... 

The high prevalence of shoulder pain in using walkers in patients who have spinal cord injury (SCI). Also, the limited options available to economically measure grip forces in walkers, which drove the need to create one. This article describes a method to obtain upper-extremities’ forces and moments in a person with SCI by designing an appropriate instrumented walker. First, since the commercial multidirectional loadcells are too expensive, custom loadcells are fabricated. Ultimately, a complete gait analysis by means of VICON motion analysis and using inverse dynamic method has been held to measure upper-extremities’ efforts. The results for a person with SCI using a two-wheel walker in low... 

The high prevalence of shoulder pain in using walkers in patients who have spinal cord injury (SCI). Also, the limited options available to economically measure grip forces in walkers, which drove the need to create one. This article describes a method to obtain upper-extremities’ forces and moments in a person with SCI by designing an appropriate instrumented walker. First, since the commercial multidirectional loadcells are too expensive, custom loadcells are fabricated. Ultimately, a complete gait analysis by means of VICON motion analysis and using inverse dynamic method has been held to measure upper-extremities’ efforts. The results for a person with SCI using a two-wheel walker in low... 

To help walking, using assistive devices can be considered to reduce the loads caused by weight and to effectively decrease the propulsive forces. In this study, a mobility Saddle-Assistive Device (S-AD) supporting body weight while walking was evaluated on two healthy volunteers. This device is based on the support of body weight against gravity with the help of a saddle, which is not used in other passive mobility assistive devices. To prove the efficiency of this device, the experimental results obtained while walking with this device were compared with those related to walking without the assistive device. The results showed that this device could significantly reduce the forces and... 

Background: The use of knee-ankle-foot orthoses with drop locked knee joints produces some limitations for walking in subjects with quadriceps muscle weakness. The development of stance control orthoses can potentially improve their functionality. Objectives: The aim of this review was to compare the evidence of the effect of stance control orthoses to knee-ankle-foot orthoses with drop locked knee joints in improving kinematic variables and energy efficiency of walking by subjects with quadriceps muscle weakness caused by different pathologies. Study design: Literature review. Methods: Based on selected keywords and their composition, a search was performed in Google Scholar, PubMed,... 

Individuals with spinal cord injury (SCI) at lower thoracic levels might walk independently with the aid of mechanical orthoses and walker by using their unimpaired trunk and upper extremity muscles (TUEM). The required motor skills and the associated subtasks of the paraplegic locomotion, however, have not been well understood yet. The purpose of this study was to investigate the coordination of the TUEM activities throughout the paraplegic gait cycle using synergy analysis. For eight paraplegic individuals (30.6 ± 11.6 years; SCI level: T12), the kinematics data and the surface electromyography (EMG) signals of TUEM were recorded during 15 gait cycles. Non-negative matrix factorization... 

Patella is the latest addition to the animal's skeleton. It's role in normal walking has not been clearly defined. A 9-year-old girl with congenital absence of the patella was assessed using instrumented gait analysis. The results show a tendency for the limb for external rotation, which is more pronounced during swing. We suggest that the role of the patella is mainly to redirect the force of the quadriceps tendon medially. The classically described role, which is to increase the lever arm of the quadriceps tendon, was not confirmed in this study. © 2018 Elsevier B.V  

This paper presents a novel Gait Pattern Generator ((IPC) developed for the "Alice" social humanoid robot, which up to now lacked an appropriate walking pattern. Due to t he limitations of this robot, the proposed gate pattern generator was formulated based on a nine-mass model to decrease the modeling errors and t he inverse kinematics of the whole lower-body was solved in such a way that the robot remained statically stable during t he movements. The main challenge of this work was to solve t he inverse kinematics of a 7-link chain with 12 degrees of freedom. For this purpose, a new graphical-numerical technique has been provided using the definition of the kinematic equations of the robot... 

This paper presents a novel Gait Pattern Generator ((IPC) developed for the "Alice" social humanoid robot, which up to now lacked an appropriate walking pattern. Due to t he limitations of this robot, the proposed gate pattern generator was formulated based on a nine-mass model to decrease the modeling errors and t he inverse kinematics of the whole lower-body was solved in such a way that the robot remained statically stable during t he movements. The main challenge of this work was to solve t he inverse kinematics of a 7-link chain with 12 degrees of freedom. For this purpose, a new graphical-numerical technique has been provided using the definition of the kinematic equations of the robot... 

Common methods of gait generation of bipedal locomotion based on experimental results, can successfully synthesize biped joints' profiles for a simple walking. However, most of these methods lack sufficient physical backgrounds which can cause major problems for bipeds when performing fast locomotion such as running and jumping. In order to develop a more accurate gait generation method, a thorough study of human running and jumping seems to be necessary. Most biomechanics researchers observed that human dynamics, during fast locomotion, can be modeled by a simple spring loaded inverted pendulum system. Considering this observation, a simple approach for bipedal gait generation in fast... 

In this paper a complete design of a high speed optical motion analyzer system has been described. The main core of the image processing unit has been implemented by the differential algorithm procedure. Some intelligent and conservative procedures that facilitate the search algorithm have also been proposed and implemented for the processing of human motions. Moreover, an optimized modified direct linear transformation (MDLT) method has been used to reconstruct 3D markers positions which are used for deriving kinematic characteristics of the motion. Consequently, a set of complete tests using some simple mechanical devices were conducted to verify the system outputs. Considering the system... 

Background and Purpose: Understanding the role and significance of trunk and upper extremity muscles in paraplegic gait can help in designing more effective assistive devices for these patients and also provides valuable information for improving muscle strengthening programs. Methods: In a patient with a spinal cord injury (SCI) who could walk independently (rating scale of ambulatory capacity, 9) with the aid of bilateral ankle-foot orthosis and a walker, the kinematics, kinetics and electromyographic (EMG) activities of 16 muscles from the trunk and upper and lower extremities were recorded during gait. The onset, cessation, and duration of the EMG signal were associated with the 4 phases... 

Paraplegic users of mechanical walking orthoses, e.g. advanced reciprocating gait orthosis (ARGO), often face high energy expenditure and extreme upper body loading during locomotion. We studied the effect of kinematical pattern on the mechanical performance of paraplegic locomotion, in search for an improved gait pattern that leads to lower muscular efforts. A three-dimensional, four segment, six-degrees-of-freedom skeletal model of the advanced reciprocating gait orthosis-assisted paraplegic locomotion was developed based on the data acquired from an experimental study on a single subject. The effect of muscles was represented by ideal joint torque generators. A response surface analysis...