Search

Running is one of the ‘low-cost’ popular activities for both competition and leisure. High occurrence of running injuries are observed due to repetitive loading on the lower extremities musculoskeletal structure. Although the association between shoes cushioning with running biomechanics have been established, the detailed relationships are yet to be identified due to limited instrumentation setup in exploring such association. This study compares the mechanical aging of shoe cushioning via developed instrumentation system versus the hydraulic testing machine. Preliminary comparisons between the latter were explored in this study.

Inspired by the human upper extremity, a musculoskeletal dual-arm manipulator is designed for light machining tasks such as hammering and sawing. We claim that musculoskeletal structure has the advantage over conventional robot structures in terms of less internal impulsive forces while performing these machining tasks. We investigated the advantages (in terms of external and internal impulses) of a musculoskeletal dual-arm model over a dual-arm model without muscles, musculoskeletal single arm model, and single arm model without muscles. Moreover, to model the hardness of the material during these tasks, an effective mass model was newly developed and experimentally verified for two different (soft and hard) materials. In order to validate the proposed methodology, a belted ellipsoid denoting the external and internal impulse geometry is employed to analyze the sawing and hammering tasks. Finally, it was found by performing a hammering task that the musculoskeletal dual-arm model is more effective in terms of generating more external impulse while experiencing less internal impulses at the joints.

This letter presents the advantages of human-like closed-chain architecture through the analytical computation of internal impulses experienced at joints and external impulses felt at the end point of the human-like manipulator during interaction with environment. The proposed human-like architecture consists of multiple closed-chains which are corresponding to mono- and biarticular muscles of the human-body. Especially, we investigate the contribution of mass and effect of change of mass of mono- and biarticular muscle models on external and internal impulses. The roles of mass of monoarticular and biarticular muscle models on internal and external impulses are analyzed in terms of new impulse measures. As an illustrative example, a 2-DOF manipulator resembling the musculoskeletal structure of the human upper extremity is introduced to examine the external and internal impulses, based on the proposed analytical tools. And it is discovered through simulation and experiment work that by increasing the mass of muscle models the external impulse is increased and internal impulses are decreased. Furthermore, it is observed that biarticular muscle models contribute more in external impulse and monoarticular muscle models absorbed more internal impulses than biarticular muscle models.

The unique musculoskeletal structure of the human hand brings in wider dexterous capabilities to grasp and manipulate a repertoire of objects than the non-human primates. It has been widely accepted that the orientation and the position of the thumb plays an important role in this characteristic behavior. There have been numerous attempts to develop anthropomorphic robotic hands with varying levels of success. Nevertheless, manipulation ability in those hands is to be ameliorated even though they can grasp objects successfully. An appropriate model of the thumb is important to manipulate the objects against the fingers and to maintain the stability. Modeling these complex interactions about the mechanical axes of the joints and how to incorporate these joints in robotic thumbs is a challenging task. This article presents a review of the biomechanics of the human thumb and the robotic thumb designs to identify opportunities for future anthropomorphic robotic hands.

Carriage of school items by children remains an issue of concern, mainly due to the large loads they have to bear, starting from early age when the musculoskeletal structure is still under development. As such, children are potentially exposed to important risks of acute or chronic injuries due to such carriage. While backpack remains the most common modality, in recent years trolley bags are increasingly considered and used. Trolleys may be of benefit, as much of the load can supported by the ground, and the muscular effort is limited to a pulling force. Nevertheless, there are situations (like stair ascent and descent, steps, and ramps) where the pulling force increases or, in some cases, has to be fully supported by a single arm. Under such conditions, the use of trolley bag might be disadvantageous versus a backpack, in that the latter allows a symmetrical distribution of the load on the body in a range of conditions. To provide more empirical evidence, which at present is very limited, this study aimed to characterize the pulling forces needed when using a school trolley bag, on a route that includes level and inclined ground surface, steps, and stairs. A sample of 195 students of primary school (age 8-11) participated, and they were asked to pull an instrumented trolley loaded with school items (total load = 62 N) from the school entrance to a classroom located one floor up in the school building. The results, expressed in terms of “pulling force vs. time” curves, show that particularly during stairs ascent and descent, one arm may exert quite large dynamic forces, and that these forces can be up to twice the mass of the carried load. Although exposure to such loads is quite limited, the methodology described here highlights the potential for concern and provides a basis for future investigations of the contribution of trolley bag carriage and disorders of the arm-shoulder complex among children.

Adjustable springs have been employed in robotic applications including physical interaction with humans or the environment. In this paper, planar multi-degree-of-freedom spring mechanisms with adjustable springs are investigated from a viewpoint of stiffness. We propose multi-degree-of-freedom biomimetic spring mechanisms inspired by the musculoskeletal structure of the human upper-extremity, which possesses highly nonlinear kinematic coupling among redundant muscles within its structure. The stiffness characteristics in the operational space of the proposed and conventional mechanisms with torsional springs are analyzed. The stiffness solution of springs for a certain workspace is given and the applicability of these mechanisms is verified through simulation.

SUMMARY Technological advances are often inspired by nature, considering that engineering is frequently faced by the same challenges as organisms in nature. One such interesting challenge is creating a structure that is at the same time stiff in a certain direction, yet flexible in another. The seahorse tail combines both radial stiffness and bending flexibility in a particularly elegant way: even though the tail is covered in a protective armour, it still shows sufficient flexibility to fully function as a prehensile organ. We therefore study the complex mechanics and dynamics of the musculoskeletal system of the seahorse tail from an engineering point of view. The seahorse tail derives its combination of flexibility and resilience from a chain of articulating skeletal segments. A versatile dynamic model of those segments was constructed, on the basis of automatic recognition of joint positions and muscle attachments. Both muscle structures that are thought to be responsible for ventral and ventral–lateral tail bending, namely the median ventral muscles and the hypaxial myomere muscles, were included in the model. Simulations on the model consist mainly of dynamic multi-body simulations. The results show that the sequential structure of uniformly shaped bony segments can remain flexible because of gliding joints that connect the corners of the segments. Radial stiffness on the other hand is obtained through the support that the central vertebra provides to the tail plating. Such insights could help in designing biomedical instruments that specifically require both high bending flexibility and radial stiffness (e.g. flexible stents and steerable catheters).Copyright © 2012 John Wiley & Sons, Ltd.

In this study, a musculoskeletal robot is used as a tool to investigate how animals control their complex body. Sprinting is a challenging task that requires maximizing the potential resources of a musculoskeletal structure. Our approach to robotic sprinting is the Athlete Robot — a musculoskeletal robot with elastic blade feet controlled by feedforward motor command. We use a catapult launcher to provide a stable start to a sprint, and then examine the relation between the initial velocity imparted by the launcher and the change in orientation of the robot. We also investigate the influence of the change in elasticity of the blade foot. The results show that acceleration causes anterior inclination after the first step. The elasticity of the foot dominates the duration of the support phase. The musculoskeletal system of the Athlete Robot is modified to suit catapulted running. Based on the results from real robot experiments, we can provide a consistent propelling force using the catapult launcher. We de...

The human body possesses a musculoskeletal structure in which muscles exist around the bones and joints. The musculoskeletal tendon-driven robot utilizes this structure. This robotic system uses sets of mechanical tendons, such as wire-cables and actuators instead of the vital muscles. The redundant actuation is necessary for the system when it does not actively use any external force nor a tensioner because the mechanical tendon can transmit only a tensile force. This structural characteristic enables feedforward motion-generation that does not need any sensory feedback. However, the convergent posture strongly depends on the tendon-arrangement. Targeting the tendon-driven manipulator, which has two links and six tendons, this paper expands the mathematical conditions for the convergence into the geometric conditions of tendon-arrangement. Based on the geometric conditions, a design method of the tendon-arrangement is discussed.

Humans can walk stably and adaptively in the presence of various environmental changes. Their bodies have very complex musculoskeletal structures that contribute to their walking stability and adaptability. In this paper, we focus on the gluteus medius, one of muscles contributing to the support of the pelvis. The gluteus medius supports the pelvis when the leg is in a standing position, but it should not inhibit its smooth swing motion. This mechanism is assumed to be realized by the musculoskeletal structure. This paper is devoted to explaining the mechanism by reproducing it using artificial pneumatic muscles. We developed a musculoskeletal robot with a gluteus medius, and showed that the mechanism is well-designed for realizing two seemingly contradictory functions: being stiff to support the pelvis while standing and being smooth to allow swinging. This finding can be utilized for adaptive walking of musculoskeletal humanoid robots.

This paper presents a tendon-driven dexterous hand capable of object manipulation. This dexterous hand is anatomically sound and mimics the musculoskeletal structure of human fingers including the passive mechanism, bone geometry, tendon network. One of the key features of this prosthetic hand is the ability to perform fine finger manipulation motions such as holding a pen with two fingers and rotating the pen. With this feature the user of the prosthesis will be potentially capable of performing a wider range of motions and tasks, which is the key feature missing from current commercially prosthetic hand available today. Some of these tasks can include holding utensils, performing fine manipulation movements in manufacturing settings, as well as many other tasks to greatly assist the user of the prosthesis.

Although robotic locomotion have greatly advanced over the past years, the abyss that separates such locomotion from even the simplest animal locomotions prompt us to approach robotic locomotion taking cues from animals. The animal musculoskeletal structure, often ignored by roboticists due to its high redundancy and complexity, might hold the secret for self-stable locomotion observed in bipeds and quadrupeds. Aiming to better understand how muscles contribute to self-stable locomotion we take the feline structure as a model on a biomimetic approach. Using 6 air muscles per hindlimb to mimic real muscles, this robot walks stably on a treadmill while supported by a slider, simulating forelimbs. We individually evaluate muscle contribution to walking stability, performing a comparison between mono and biarticular synergistic muscles at the ankle and concluding that a higher compliance on the biarticular muscle improved walking stability. A better understanding of such complex phenomena may help on the development of better legged robots in the future, truly taking advantage of concepts developed by nature over the years.

Recently, research into robots that coexist with people in many areas such as the service and medical industries is active. Such robots need to be both safe and flexible. To satisfy this demand, a pneumatic actuator is appropriate because it is lightweight and has natural compliance. Our research focuses on a joint angle control method for a five-fingered robot hand using low-pressure driven pneumatic actuators. This robot mimics appearance of a human hand and musculoskeletal structure, which has antagonistic muscle pairs for each joint. We proposed a biologically-inspired control method using the following parameters: “antagonistic muscle ratio” and “antagonistic muscle activity”. We also investigated the validity of the proposed method by implementing it in a one-degree-of-freedom joint model, developed a feedback control system and conducted the joint angle control.

In a musculoskeletal structure, the internal force among muscles plays an important role. Changing the internal force enables to control not only joint angles but also impedance, so that vertebrate animals can produce a motion according to a situation. Focusing on a musculoskeletal system with two links and six muscles, this paper investigate the effect of biarticular muscles when feedforward position control is inputted. This control gives the constant internal force balancing at desired posture as feedforward input, based on the EP hypothesis in physiology. From the result, we point out that the biarticular muscles can reduce the convergent time of the motion, and they also can stabilize the system.

We are developing dynamic computer models of surgical jaw reconstructions in order to determine the effect of altered musculoskeletal structure on the biomechanics of mastication. We aim to predict post-reconstruction deficits in jaw motion and force production. To support these research goals we have extended our biomechanics simulation toolkit, ArtiSynth [1], with new methods relevant to surgical planning. The principle features of ArtiSynth include simulation of constrained rigid-bodies, volume-preserving finite-element methods for deformable bodies, contact between bodies, and muscle models. We are adding model editing capabilities and muscle activation optimization to facilitate progress on post-surgical simulation. Our software and research directions are focused on upper-airway and cranio-facial anatomy, however the toolset and methodology are applicable to other musculoskeletal systems.

Animals are capable of generating locomotion adaptive to various environments by coordinated regulation of a complex musculoskeletal system. Such intelligent locomotor mechanisms seem to emerge partly from intrinsic mechanical properties of the musculoskeletal system. This paper outlines some of the biomechanical elements exploited for the generation of adaptive locomotion in animals, and present an anatomically based biomechanical model of a Japanese monkey being constructed to elucidate the dynamic principles embedded in inherent musculoskeletal structures underlying the emergence of adaptive locomotion.

Recent advances in fields of anatomy, physiology, orthopedics and physical education made it necessary to seek better techniques for mathematical modeling and analysis of the musculoskeletal structure. Innumerable investigators [see Bibliography of Ref. (1)] have attempted in the past years to analyze the human body mechanics with simplified models in order to obtain quantitative information on the forces in the different bones, muscles and joints. This study deals with the development of a rigorous computer simulation of the lower extremities of the musculoskeletal system with the objective of obtaining a generalized procedure for quantifying the participation of the individual muscles and groups of muscles in maintaining different postures or producing particular motions according to preselected criteria.