Search results

Mobility is one of the important elements in clothing design. The purpose of this paper is to examine the predictability of clothing mobility via musculoskeletal simulation.

In order to carry out the musculoskeletal simulation considering the influence of clothing, simulation of the dressed state was attempted. This paper simulated the dressed state and measured the motion-related deformation of the clothing to estimate the force applied to the human body based on the material property of the clothing samples. The dressed state was simulated using an external force in the musculoskeletal model.

When the elbow flexion torque with an elbow supporter was calculated using the above-mentioned method of musculoskeletal simulation, it was confirmed that the lower the stretchability of the sample, the higher the elbow flexion torque. In addition, the sensory evaluation performed under the same condition as that in the simulation showed that the lower the joint torque during the motion, the higher the subjective mobility, and that the higher the joint torque, the lower the subjective mobility. Thus, it is suggested that musculoskeletal simulation of the dressed state can predict the clothing mobility.

However, the method proposed in this paper requires the measurement of the deformation of the clothing to estimate the force applied to the human body. Thus, it is difficult to apply this in the measurement of general clothing that allows enough space between it and the human body, requiring further improvement of the dressed state simulation method.

Because it is difficult to estimate the force applied by the clothing to the human body, only a few studies have performed analysis on the effect of clothing by using musculoskeletal simulation. Conversely, although the force applied by the clothing to the human body needs to be estimated in advance by the measurement of the deformation, the utility of the simulation in clothing design seems to be high because the simulation can estimate clothing mobility and the effects of clothing on muscle activity.

Limited by the types of sensors, the state information available for musculoskeletal robots with highly redundant, nonlinear muscles is often incomplete, which makes the control face a bottleneck problem. The aim of this paper is to design a method to improve the motion performance of musculoskeletal robots in partially observable scenarios, and to leverage the ontology knowledge to enhance the algorithm’s adaptability to musculoskeletal robots that have undergone changes.

A memory and attention-based reinforcement learning method is proposed for musculoskeletal robots with prior knowledge of muscle synergies. First, to deal with partially observed states available to musculoskeletal robots, a memory and attention-based network architecture is proposed for inferring more sufficient and intrinsic states. Second, inspired by muscle synergy hypothesis in neuroscience, prior knowledge of a musculoskeletal robot’s muscle synergies is embedded in network structure and reward shaping.

Based on systematic validation, it is found that the proposed method demonstrates superiority over the traditional twin delayed deep deterministic policy gradients (TD3) algorithm. A musculoskeletal robot with highly redundant, nonlinear muscles is adopted to implement goal-directed tasks. In the case of 21-dimensional states, the learning efficiency and accuracy are significantly improved compared with the traditional TD3 algorithm; in the case of 13-dimensional states without velocities and information from the end effector, the traditional TD3 is unable to complete the reaching tasks, while the proposed method breaks through this bottleneck problem.

In this paper, a novel memory and attention-based reinforcement learning method with prior knowledge of muscle synergies is proposed for musculoskeletal robots to deal with partially observable scenarios. Compared with the existing methods, the proposed method effectively improves the performance. Furthermore, this paper promotes the fusion of neuroscience and robotics.

The aim of this paper is to present and evaluate a methodology for automatically constructing and applying the physiologically‐realistic boundary/loading conditions for use in the structural finite element analysis of the femur during various exertion tasks (e.g. gait/walking).

To obtain physiologically‐realistic boundary/loading conditions needed in the femur structural finite element analysis, a whole‐body musculoskeletal inverse dynamics analysis is carried out and the resulting muscle forces and joint reaction forces/moments extracted.

The finite element results obtained are compared with their counterparts available in literature and it is found that the overall agreement is acceptable while the highly automated procedure for the finite element model generation developed in the present work made the analysis fairly easy and computationally highly efficient. Potential sources of errors in the current procedure have been identified and the measures for their mitigation recommended.

The present approach enables a more accurate determination of the physiological loads experienced by the orthopedic implants which can be of great value to implant designers and orthopedic surgeons.

The purpose of this paper is to compare fracture‐fixation and bone‐healing promotion efficacies of an intramedullary (IM) nail‐type and an external osteosynthesis plate‐type femoral trochanteric‐fracture implants using the results of a combined multi‐body dynamics and finite element analyses. For both implants, fracture fixation was obtained using a dynamic hip blade which is anchored to the femur head on one end and is connected to the IM rod/plate on the other. The analysis was carried out for two pre‐fracture conditions of the femur: healthy and osteoporotic.

The musculoskeletal dynamics portion of the analysis was used to obtain realistic physiological loading conditions (i.e. muscle forces and joint reaction forces and moments) associated with four typical everyday activities of a patient, namely, walking, lunging, cycling and egress (i.e. exiting a passenger vehicle). The subsequent structural finite element analysis of the fractured femur/implant assembly was employed to quantify fracture‐fixation efficacy (as measured by the extents of lateral (found to be minor), flexural and torsional displacements of the two femur fragments) and the bone‐healing promotion efficacy (as quantified by the fraction of the fractured surface area which experienced desirable contact pressures).

The results obtained show that, in general, the IM‐rod type of implant out‐performs the osteosynthesis plate type of implant over a large range of scenarios involving relative importance of the bone‐healing promotion and fracture‐fixation efficacies, health condition of the femur and the activity level of the patient. More specifically, the more active the patient and the larger extent of osteoporosis in the femur, the more justifiable is the use of the IM‐rod type of implant.

The present approach enables assessment of the fracture‐fixation performance of orthopedic implants under physiologically realistic loading conditions.

This paper aims to design and control of a novel compact transportation system called the “wearable vehicle”. The wearable vehicle allows for traversing all types of terrains while transporting one's luggage in a comfortable and efficient manner.

The proposed design consists of a lower limb exoskeleton carrying two motorized wheels and two free wheels installed alongside its feet. This paper presents a detailed description of the system with its preliminary design and finite element analysis. Moreover, the system has been optimally designed to decrease wearable vehicle’s total weight, consequently leading to a reduction in motor size. Finally, two controllers have been designed to achieve stable operation of the wearable vehicle while walking. A PD controller with gravity compensation has been designed to ensure that the wearable vehicle tracks human motion, while a PID controller has been designed to ensure that the zero moment point is close to the center of the system’s support polygon.

Experimental tests were carried out to check the wearable vehicle concept. The obtained results prove the feasibility of the proposed wearable vehicle from the design, dynamics and control viewpoints.

This proposed wearable vehicle’s purpose is for traveling faster with less effort than normal walking. When a human comes across a flat open ground, the wearable vehicle can be used as a vehicle. However, when a human enters crowded traffic, an unstructured area or other obstacles like stairs, the vehicle can be switched into walking mode.

The wearable vehicle has seven DOFs exoskeletons, two motorized wheels, two free wheels and a foldable seat. It is used as a vehicle via its motorized and free wheels to travel fast with minimal effort. In addition, the human can switch easily into walking mode, if there is unstructured terrain to be traversed. Furthermore, an illustration of system's mechanisms and main feature parameters are presented to become acquainted with the ultimate benefits of the new system.

Tribological research is complex and multidisciplinary, with many parameters to consider. As traditional experimentation is time-consuming and expensive due to the complexity of tribological systems, researchers tend to use quantitative and qualitative analysis to monitor critical parameters and material characterization to explain observed dependencies. In this regard, numerical modeling and simulation offers a cost-effective alternative to physical experimentation but must be validated with limited testing. This paper aims to highlight advances in numerical modeling as they relate to the field of tribology.

This study performed an in-depth literature review for the field of modeling and simulation as it relates to tribology. The authors initially looked at the application of foundational studies (e.g. Stribeck) to understand the gaps in the current knowledge set. The authors then evaluated a number of modern developments related to contact mechanics, surface roughness, tribofilm formation and fluid-film layers. In particular, it looked at key fields driving tribology models including nanoparticle research and prosthetics. The study then sought out to understand the future trends in this research field.

The field of tribology, numerical modeling has shown to be a powerful tool, which is both time- and cost-effective when compared to standard bench testing. The characterization of tribological systems of interest fundamentally stems from the lubrication regimes designated in the Stribeck curve. The prediction of tribofilm formation, film thickness variation, fluid properties, asperity contact and surface deformation as well as the continuously changing interactions between such parameters is an essential challenge for proper modeling.

This paper highlights the major numerical modeling achievements in various disciplines and discusses their efficacy, assumptions and limitations in tribology research.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-03-2023-0076/

This study aimed to develop a method to calculate the mattress indentation for further estimating spinal alignment.

A universal indentation calculation model is derived based on the system theory, and the deformation characteristics of each component are analyzed by the finite element (FE) model of a partial air-spring mattress under the initial air pressure of 0.01–0.025 MPa. Finally, the calculation error of the model is verified.

The results indicate that the indentation calculation model could describe the stain of a mattress given the load and the constitutive model of each element. In addition, the FE model of a partial air-spring mattress can be used for further simulation analysis with an error of 1.47–3.42 mm. Furthermore, the deformation of the series system is mainly contributed by the air spring and the components directly in contact with it, while the top component is mainly deflection deformation. In addition, the error of the calculation model is 2.17–5.59 mm on the condition of 0.01–0.025 MPa, satisfying the engineering application. Finally, the supine spinal alignment is successfully extracted from the mattress indentation.

The limitation of this study is that it needs to verify the practicality of the indentation calculation model for the Bonnier spiral spring mattress. The main feature of the Bonnier spring mattress is that all springs are connected, so the mattress deflection and neighborhood effect are more significant than those of the air-spring mattress. Therefore, the applicability of the model needs to be tested. Moreover, it is worth further research to reduce the deformation error of each component.

As part of the series of studies on the intelligent air-spring mattress, the indentation-based evaluation method of spinal alignment in sleep postures will be studied for hardness and intelligent regulation based on this study.

The results of this research are ultimately used for the intelligent adjustment of air-spring mattresses, which automatically adjusts the hardness according to the user's sleep postures and spinal alignment, thus maintaining optimal spinal biomechanics. The successful application of this result could improve the sleep health of the general public.

Based on the series system theory, an indentation calculation model for mattresses with arbitrary structure is proposed, overcoming the dependence of parameters on materials and their combinations when fitting the Burgers model. Further, the spinal alignment in supine posture is extracted from the indentation, laying a theoretical foundation for further recognition and adjustment of the spinal alignment of the intelligent mattress.

Exoskeletons are moving into industries with the potential to reduce muscle strains and prevent occupational injuries. Although exoskeletons have been designed and tested in laboratory settings, rare empirical studies of their application in construction have been reported. Therefore, the purpose of this study is on in a real-life setting testing the applicability of adopting exoskeletons in the construction industry.

A feasibility study of exoskeletons in construction is conducted by testing a passive exoskeleton, designed for shoulder support. Five bricklayers tested in a two-month period the exoskeleton, each wearing it for a three-day period while carrying out normal work activities. Test data in terms of interviews were collected and analyzed using qualitative content analysis.

The application of exoskeletons in construction revealed several limitations, where the two primary ones are the exoskeleton is not designed while considering the tasks of a bricklayer causing several challenges and the exoskeleton only supports a single upward motion while limiting other movements and even counteracted when a downward movement was necessary.

The identified challenges could easily have been revealed by coupling the design and testing of exoskeletons to actual application. Thus, the design approach needs to be reversed. Instead of designing an exoskeleton to support a specific body part or motion and then identifying where it is applicable, it should target specific industries and focus on the actual work and movements and the necessary support. As part of the change, the design metrics should be reevaluated to reflect the work to support.

The purpose of this paper is to present a method of digital twins of female bodies and the optimization of wetsuit patterns with the help of virtual technologies.

First, the new anthropometrical grouping of female torsos has been developed with 3D body scanning technology. Second, soft tissue deformation under the influence of typical diving postures and hydraulic pressure has been explored. Through real experiments, the relationship between textile material strain and body measurement changing has been applied to establish deformed digital twins of female bodies. Finally, during the evaluation of the virtual wetsuit test on digital twins through material strain and pressure values in CLO 3D, the optimized pattern of the wetsuit has been designed.

The experimental results show that the digital twins based on real data transformation are feasible and practical, and the process of establishing digital twins with 3D body scanning technology is valid and accurate.

The researches on the wetsuit of structure and body dynamic measurements still have many gaps existing in the real and virtual experiments. Thus the manuscript addresses these issues and provides the deformed digital twin for wetsuit pattern design for the first time. This study can be used for designing and optimizing the wetsuit and further improving the efficiency of manufacture and evaluation.

Human-like musculoskeletal robots can fulfill flexible movement and manipulation with the help of multi joints and actuators. However, in general, sophisticated structures, accurate sensors and well-designed control are all necessary for a musculoskeletal robot to achieve high-precision movement. How to realize the reliable and accurate movement of the robot under the condition of limited sensing and control accuracy is still a bottleneck problem. This paper aims to improve the movement performance of musculoskeletal system by bio-inspired method.

Inspired by two kinds of natural constraints, the convergent force field found in neuroscience and attractive region in the environment found in information science, the authors proposed a structure transforming optimization algorithm for constructing constraint force field in musculoskeletal robots. Due to the characteristics of rigid-flexible coupling and variable structures, a constraint force field can be constructed in the task space of the musculoskeletal robot by optimizing the arrangement of muscles.

With the help of the constraint force field, the robot can complete precise and robust movement with constant control signals, which brings in the possibility to reduce the requirement of sensing feedback during the motion control of the robot. Experiments are conducted on a musculoskeletal model to evaluate the performance of the proposed method in movement accuracy, noise robustness and structure sensitivity.

A novel concept, constraint force field, is proposed to realize high-precision movements of musculoskeletal robots. It provides a new theoretical basis for improving the performance of robotic manipulation such as assembly and grasping under the condition that the accuracy of control and sensory are limited.