[Research of Kinematics and Kinetics Models of Human Knee Joint].

Human knee joint as a research object, it has become an effective way to establish models of human knee joint. The types of human knee joint models are identified, and each type of model is simply introduced respectively. Focusing on the types of the kinematics and kinetics models of human knee joint on the basis of anatomy, the current research status is detailedly described and comprehensively analyzed at home and abroad correspondingly. Through in-depth study the various kinematics and kinetics models, and their advantages and limitations are discovered. The existing problems are summarized, solution and development trend are also proposed.

Multimodal human computer interaction of wheelchairs supporting lower limb active rehabilitation.

Currently, an important challenge in stroke rehabilitation is how to effectively restore motor functions of lower limbs. This paper presents multimodal human computer interaction (HCI) of wheelchairs supporting lower limb active rehabilitation. First, multimodal HCI incorporating motor imagery electroencephalography (EEG), electromyography (EMG) and speech is designed. Second, prototype supporting wheelchair active rehabilitation method is illustrated in details. Third, the preliminary brain-computer interfaces (BCI) and speech recognition task experiments are carried out respectively, and the results are obtained. Finally, discussion is conducted and conclusion is drawn. This study has important practical significance in auxiliary movements and neurorehabilitation for stroke patients.

The Comfort and Measurement Precision-Based Multi-Objective Optimization Method for Gesture Interaction.

As an advanced interaction mode, gestures have been widely used for human-computer interaction (HCI). This paper proposes a multi-objective optimization method based on the objective function JCP to solve the inconsistency between the gesture comfort JCS and measurement precision JPH in the gesture interaction. The proposed comfort model CS takes seventeen muscles and six degrees of freedom into consideration based on the data from muscles and joints, and is capable of simulating the energy expenditure of the gesture motion. The CS can provide an intuitive indicator to predict which act has the higher risk of fatigue or injury for joints and muscles. The measurement precision model ∆PH is calculated from the measurement error (∆XH,∆YH,∆ZH) caused by calibration, that provides a means to evaluate the efficiency of the gesture interaction. The modeling and simulation are implemented to analyze the effectiveness of the multi-objective optimization method proposed in this paper. According to the result of the comparison between the objective function JCS, based on the comfort model CS, and the objective function JPH, based on the measurement precision models ∆PH, the consistency and the difference can be found due to the variation of the radius rB_RHO and the center coordinates PB_RHOxB_RHO,yB_RHO,zB_RHO. The proposed objective function JCP compromises the inconsistency between the objective function JCS and JPH. Therefore, the multi-objective optimization method proposed in this paper is applied to the gesture design to improve the ergonomics and operation efficiency of the gesture, and the effectiveness is verified through usability testing.

Reconstruction and optimization of the 3D geometric anatomy structure model for subject-specific human knee joint based on CT and MRI images.

BACKGROUND: Nowadays, the total knee arthroplasty (TKA) technique plays an important role in surgical treatment for patients with severe knee osteoarthritis (OA). However, there are still several key issues such as promotion of osteotomy accuracy and prosthesis matching degree that need to be addressed. OBJECTIVE: It is significant to construct an accurate three-dimensional (3D) geometric anatomy structure model of subject-specific human knee joint with major bone and soft tissue structures, which greatly contributes to obtaining personalized osteotomy guide plate and suitable size of prosthesis. METHODS: Considering different soft tissue structures, magnetic resonance imaging (MRI) scanning sequences involving two-dimensional (2D) spin echo (SE) sequence T1 weighted image (T1WI) and 3D SE sequence T2 weighted image (T2WI) fat suppression (FS) are selected. A 3D modeling methodology based on computed tomography (CT) and two sets of MRI images is proposed. RESULTS: According to the proposed methods of image segmentation and 3D model registration, a novel 3D knee joint model with high accuracy is finally constructed. Furthermore, remeshing is used to optimize the established model by adjusting the relevant parameters. CONCLUSIONS: The modeling results demonstrate that reconstruction and optimization model of 3D knee joint can clearly and accurately reflect the key characteristics, including anatomical structure and geometric morphology for each component.

Intelligent infusion controller with a physiological information feedback function.

BACKGROUND: In hospitals, some problems still exist, such as transfusion reaction that cannot be dealt with in time, medical staff cannot observe the physiological information of the infusion patients in real time, and the infusion speed cannot be controlled smartly. OBJECTIVE: To address these problems, we propose a method for intelligent monitoring and designed a controller for dripping speed regulation. METHODS: A photoelectric sensor was used to obtain the heart rate (HR) information, and a PID parameter self-tuning controller based on the fuzzy control principle was developed to establish a multi-stage adaptive control method based on HR feedback. By controlling the rotation of the motor to drive the cam to control the drip rate smartly. Also, the infusion and physiological information are transmitted to the nurse station to monitor the possible transfusion reaction. RESULTS: The experiments show that the intelligent infusion controller can achieve HR signal detection with an average accuracy of over 94%, dripping speed detection and adjustment with an average accuracy of above 98% and adjustment time within 35 seconds. CONCLUSION: Our study proved that the intelligent infusion controller can control the infusion process intelligently and effectively, and has excellent reliability, small steady-state error and high practical value.

Modeling and simulation of musculoskeletal system of human lower limb based on tensegrity structure.

In this paper, a mechanical model of the skeletal muscle of human lower limb system is established by using the Hill muscle model and kinetic equation of the movement of lower extremities according to the attachment positions of skeletal muscle. State vector and neural control are delineated by the direct configuration method. Changes of gait and skeletal muscle stress during walking process are analyzed with energy consumption as objective function. Results illustrate that simulation data are in good agreement with actual walking gait data. Feasibility and correctness of the designed model and control behavior of skeletal muscle tension structure are also verified.

Mechanical Energy Expenditure-based Comfort Evaluation Model for Gesture Interaction.

As an advanced interaction mode, the gesture has been widely used for the human-computer interaction (HCI). The paper proposes a comfort evaluation model based on the mechanical energy expenditure (MEE) and the mechanical efficiency (ME) to predict the comfort of gestures. The proposed comfort evaluation model takes nineteen muscles and seven degrees of freedom into consideration based on the data of muscles and joints and is capable of simulating the MEE and the ME of both static and dynamic gestures. The comfort scores (CSs) can be therefore calculated by normalizing and assigning different decision weights to the MEE and the ME. Compared with the traditional comfort prediction methods based on measurement, on the one hand, the proposed comfort evaluation model makes it possible for providing a quantitative value for the comfort of gestures without using electromyography (EMG) or other measuring devices; on the other hand, from the ergonomic perspective, the results provide an intuitive indicator to predict which act has the higher risk of fatigue or injury for joints and muscles. Experiments are conducted to validate the effectiveness of the proposed model. According to the comparison result among the proposed comfort evaluation model, the model based on the range of motion (ROM) and the model based on the method for movement and gesture assessment (MMGA), a slight difference can be found due to the ignorance of dynamic gestures and the relative kinematic characteristics during the movements of dynamic gestures. Therefore, considering the feedback of perceived effects and gesture recognition rate in HCI, designers can achieve a better optimization for the gesture design by making use of the proposed comfort evaluation model.

Design and optimization of multi-class series-parallel linear electromagnetic array artificial muscle.

Skeletal muscle exhibiting complex and excellent precision has evolved for millions of years. Skeletal muscle has better performance and simpler structure compared with existing driving modes. Artificial muscle may be designed by analyzing and imitating properties and structure of skeletal muscle based on bionics, which has been focused on by bionic researchers, and a structure mode of linear electromagnetic array artificial muscle has been designed in this paper. Half sarcomere is the minimum unit of artificial muscle and electromagnetic model has been built. The structural parameters of artificial half sarcomere actuator were optimized to achieve better movement performance. Experimental results show that artificial half sarcomere actuator possesses great motion performance such as high response speed, great acceleration, small weight and size, robustness, etc., which presents a promising application prospect of artificial half sarcomere actuator.