基于分子馬達的骨骼肌生物力學原理及其在外骨骼機器人人機力交互中應用
發(fā)布時間：2018-09-19 13:17
【摘要】：外骨骼機器人是一種穿戴式具有防護、助力和助行等功能的機器人，在軍事、康復醫(yī)療等領(lǐng)域有著巨大的應用價值和廣闊的市場前景，也是國內(nèi)外競相研究的熱點。隨著我國經(jīng)濟的快速發(fā)展，人們對生活質(zhì)量和生命健康更加關(guān)注和重視。與此同時，人口老齡化及肢殘人的增加也帶來了重大社會問題，對智能型外骨骼康復機器人有著廣泛需求。但是，由于存在可穿戴性、高可靠性、人機交互、智能控制等技術(shù)難點，，真正走向臨床應用的外骨骼機器人仍不多見，高性能的人機交互接口及交互技術(shù)成為制約其應用的瓶頸問題之一，而其中與外骨骼人機力交互技術(shù)密切相關(guān)的人機力交互機理，特別是骨骼肌收縮生物力學原理非常值得深入探索。 本文以實現(xiàn)對人體下肢主動康復訓練為目標，開發(fā)出下肢外骨骼機器人，通過分析骨骼肌中分子馬達的納米力學特性及運行機制，探索骨骼肌生物力學原理，從微觀到宏觀構(gòu)建基于分子馬達集體運行機制的骨骼肌力學模型，并設計基于EMG信號、接觸力信號的人機交互接口，研究人與外骨骼之間力交互機理，制訂外骨骼機器人控制策略，開展了人機力交互及機器人控制實驗研究。本文的主要工作及取得的成果可以歸納為以下幾點： 一、以肌球蛋白分子馬達為對象，分析分子馬達的納米力學特性及運行機制。針對分子馬達的循環(huán)工作過程，探索了分子馬達在van der Waals力、Casimir力、靜電力及布朗力等耦合作用下向肌動蛋白絲接近并結(jié)合的運動規(guī)律，建立了分子馬達循環(huán)過程的動力學模型，通過Monte Carlo方法對分子馬達的運動過程模擬發(fā)現(xiàn)，接近過程中當分子馬達與細肌絲表面距離大于3nm時，起主要作用的力為Casimir力和靜電力；當距離小于3nm時，van der Waals力和靜電力使分子馬達向細肌絲軌道快速接近，比較這幾個力的影響可知，接近過程中靜電引力占主導，并由此闡明了分子馬達開始運行并使肌肉收縮的力學機理，解析了鈣離子在肌肉收縮中的關(guān)鍵作用，同時分析了分子馬達所處空間勢場對肌纖維結(jié)構(gòu)穩(wěn)定性的影響。 二、通過分析分子馬達集體運行特性，利用非平衡態(tài)統(tǒng)計力學方法從微觀到宏觀構(gòu)建了新的骨骼肌力學模型。首先研究分子馬達的集體運行機制，為了反映分子馬達一個循環(huán)周期的N個狀態(tài)，構(gòu)建位移變量概率密度的Fokker-Planck方程，并考慮肌小節(jié)空間結(jié)構(gòu)特征、分子馬達彈性系數(shù)、肌小節(jié)橫截面積等因素，推導出肌小節(jié)主動收縮力學模型，通過計算位移變量的概率密度分布，分析了ATP濃度、負載力對主動收縮力及收縮速度的影響。進一步地，針對骨骼肌激活與收縮過程，建立動作電位頻率與肌小節(jié)收縮力之間穩(wěn)態(tài)關(guān)系，考慮肌小節(jié)的串并聯(lián)作用，最終從微觀到宏觀建立基于分子馬達集體運行機制的骨骼肌力學模型。計算表明，隨著動作電位頻率的增加，肌漿中鈣離子濃度先線性上升并逐漸趨于飽和，主動收縮力出現(xiàn)融合并跟隨鈣離子濃度變化趨勢，當動作電位處于最大頻率時肌肉強直收縮，在ATP濃度飽和情況下，肌肉最大等長收縮力主要取決于分子馬達數(shù)目、彈性系數(shù)、肌肉橫截面積等物理參數(shù)，由于動作電位的疊加形成EMG信號，由此為開展EMG信號特征與肌肉力之間聯(lián)系研究奠定了理論基礎。 三、針對人體下肢關(guān)節(jié)運動范圍大、自由度多、關(guān)節(jié)力矩大等運動特征，從仿生學角度設計實現(xiàn)了多功能下肢外骨骼機器人，開發(fā)出并聯(lián)關(guān)節(jié)式外骨骼踝關(guān)節(jié)。外骨骼機器人系統(tǒng)結(jié)構(gòu)緊湊，膝關(guān)節(jié)轉(zhuǎn)動范圍0~110度、髖關(guān)節(jié)-25~55度，能滿足人體步行要求，并聯(lián)踝關(guān)節(jié)能實現(xiàn)人體踝關(guān)節(jié)背屈/跖屈、內(nèi)翻/外翻兩個自由度運動，外骨骼機器人適合身高在155cm~190cm的人使用，并可主動調(diào)整人體重心軌跡使之符合上下波動的特征，系統(tǒng)有較高的穩(wěn)定性和可靠性。同時開發(fā)了基于EMG信號、力觸覺信號的人機交互接口，包括傳感單元（EMG信號采集儀、交互力傳感器）、數(shù)據(jù)采集及處理單元，重點開展了人與外骨骼之間力交互機理研究，建立了外骨骼機器人的動力學模型，并以人體膝關(guān)節(jié)為對象，利用大腿骨胳肌肉系統(tǒng)進行了人體膝關(guān)節(jié)正向/逆向動力學建模，構(gòu)建EMG信號特征頻率與肌肉收縮力、關(guān)節(jié)力矩之間函數(shù)關(guān)系。 四、開展了人機力交互實驗及人機接口在外骨骼機器人主動控制中應用。首先，完善了外骨骼機器人控制系統(tǒng)并制定了滿足不同康復訓練要求的外骨骼控制策略；其次，進行了人機力交互實驗，通過采集大腿肌肉EMG信號、人與外骨骼交互力，利用EMG信號表征肌肉激活程度，根據(jù)肌肉力學模型計算肌肉收縮力和關(guān)節(jié)力矩，比較肌肉主動力矩與外骨骼對人的反作用力矩，實驗結(jié)果表明兩者之間吻合較好，證明了所構(gòu)建肌肉力學模型的合理性；最后，根據(jù)外骨骼機器人控制策略，對人體進行了被動與主動訓練，其中被動模式是按照設定的步態(tài)及角度信息完成了對人體下肢訓練，主動模式是結(jié)合人機交互接口，采集肌肉的EMG信號，利用肌肉力學模型預測關(guān)節(jié)運動所需力矩，識別人體運動意圖，根據(jù)預測信息完成了對外骨骼機器人的智能控制，實現(xiàn)了按照人體意圖的主動助力訓練。
[Abstract]:Exoskeleton robot is a kind of wearable robot with the functions of protecting, assisting and walking. It has great application value and broad market prospects in military, rehabilitation and other fields. It is also a hot research topic at home and abroad. With the rapid development of China's economy, people pay more attention to the quality of life and health. At the same time, the aging of population and the increase of the disabled also bring about major social problems, and there is a wide demand for intelligent exoskeleton rehabilitation robots. Interactive interface and interaction technology have become one of the bottlenecks restricting its application. The mechanism of human-computer interaction, especially the biomechanical principle of skeletal muscle contraction, which is closely related to exoskeleton-human interaction technology, deserves further exploration.
In this paper, a lower extremity exoskeleton robot is developed to achieve active rehabilitation training of human lower extremities. By analyzing the nanomechanical properties and operating mechanism of molecular motors in skeletal muscle, the biomechanical principle of skeletal muscle is explored. A skeletal muscle mechanical model based on the collective operation mechanism of molecular motors is constructed from micro to macro, and designed based on it. EMG signal, human-computer interaction interface of contact force signal, force interaction mechanism between human and exoskeleton is studied, control strategy of exoskeleton robot is formulated, and Experimental Research on human-computer interaction and robot control is carried out.
Firstly, taking myosin molecular motor as the object, the nanomechanical properties and operation mechanism of the molecular motor are analyzed. According to the cyclic working process of the molecular motor, the movement law of the molecular motor approaching and combining to actin filament under the coupling action of van der Waals force, Casimir force, electrostatic force and Brownian force is explored, and the molecular motor is established. The kinetic model of the cycling process was established by Monte Carlo method. It was found that when the distance between the molecular motor and the filament surface was more than 3 nm, the main forces were Casimir force and electrostatic force, and when the distance was less than 3 nm, van der Waals force and electrostatic force made the molecular motor move to the filament orbit faster. Comparing the effects of these forces, we can see that the electrostatic force is dominant in the process of approaching, and thus clarify the mechanical mechanism of the molecular motor starting to run and muscle contraction, and analyze the key role of calcium ions in muscle contraction. At the same time, we analyze the influence of the spatial potential field of the molecular motor on the stability of muscle fiber structure.
Secondly, a new skeletal muscle mechanics model is constructed by analyzing the collective operation characteristics of molecular motors and using the non-equilibrium statistical mechanics method from microscopic to macroscopic. Firstly, the collective operation mechanism of molecular motors is studied. In order to reflect the N states of a cycle of molecular motors, the Fokker-Planck equation of the probability density of displacement variables is constructed and examined. The mechanical model of active contraction of sarcomere was deduced by considering the spatial structure of sarcomere, the elastic coefficient of molecular motor and the cross-sectional area of sarcomere. The effects of ATP concentration and load on the active contraction force and contraction velocity were analyzed by calculating the probability density distribution of displacement variables. The steady-state relationship between the action potential frequency and the contraction force of sarcomeres was established. Considering the series-parallel interaction of sarcomeres, a skeletal muscle mechanical model based on the collective operation mechanism of molecular motors was established from microscopic to macroscopic. Active contraction force fuses and follows the trend of calcium ion concentration. When the action potential is at its maximum frequency, the muscles contract rigidly. When the ATP concentration is saturated, the maximum isometric contraction force mainly depends on the number of molecular motors, elastic coefficient, muscle cross-sectional area and other physical parameters. This lays a theoretical foundation for the study of the relationship between EMG signal characteristics and muscle strength.
Thirdly, according to the motion characteristics of human lower limb joints, such as wide range of motion, many degrees of freedom and large joint torque, a multi-functional lower limb exoskeleton robot is designed and implemented from the perspective of bionics, and a parallel articulated exoskeleton ankle joint is developed. For walking, the parallel ankle joint can realize the back flexion/plantar flexion of the ankle joint and the inversion/valgus motion with two degrees of freedom. The exoskeleton robot is suitable for the people whose height is between 155 cm and 190 cm, and can adjust the trajectory of the center of gravity of the human body actively to conform to the characteristics of fluctuation. The system has high stability and reliability. The human-computer interaction interface of force-tactile signal, including sensor unit (EMG signal acquisition instrument, interactive force sensor), data acquisition and processing unit, focuses on the study of force interaction mechanism between human and exoskeleton, establishes the dynamic model of exoskeleton robot, and takes human knee joint as the object, carries out the research using the thigh skeletal muscle system. The forward/reverse kinetics model of human knee joint was established to construct the functional relationship between EMG signal characteristic frequency and muscle contraction force and joint torque.
Fourthly, the human-machine interaction experiment and the application of human-machine interface in the active control of exoskeleton robot are carried out. Firstly, the control system of exoskeleton robot is improved and the exoskeleton control strategy is formulated to meet the different rehabilitative training requirements. Secondly, the human-machine interaction experiment is carried out, and the human-exoskeleton interaction is achieved by collecting the EMG signal of thigh muscle. Mutual force is represented by EMG signal, muscle contraction force and joint torque are calculated according to muscle mechanics model, and the reaction torque between muscle active torque and exoskeleton is compared. The experimental results show that the two coincide well, which proves the rationality of the muscle mechanics model. Finally, according to exoskeleton robot control. The passive mode is to complete the training of human lower limbs according to the set gait and angle information. The active mode is to collect the EMG signals of muscles by combining the human-computer interaction interface, predict the required torque of joint motion by using the muscle mechanics model, identify the human motion intention, and according to the prediction letter. It completes the intelligent control of the external skeleton robot, and realizes the active assistance training according to the human body's intention.
【學位授予單位】：上海交通大學
【學位級別】：博士
【學位授予年份】：2012
【分類號】：TH789
本文編號：2250236
[Abstract]:Exoskeleton robot is a kind of wearable robot with the functions of protecting, assisting and walking. It has great application value and broad market prospects in military, rehabilitation and other fields. It is also a hot research topic at home and abroad. With the rapid development of China's economy, people pay more attention to the quality of life and health. At the same time, the aging of population and the increase of the disabled also bring about major social problems, and there is a wide demand for intelligent exoskeleton rehabilitation robots. Interactive interface and interaction technology have become one of the bottlenecks restricting its application. The mechanism of human-computer interaction, especially the biomechanical principle of skeletal muscle contraction, which is closely related to exoskeleton-human interaction technology, deserves further exploration.
In this paper, a lower extremity exoskeleton robot is developed to achieve active rehabilitation training of human lower extremities. By analyzing the nanomechanical properties and operating mechanism of molecular motors in skeletal muscle, the biomechanical principle of skeletal muscle is explored. A skeletal muscle mechanical model based on the collective operation mechanism of molecular motors is constructed from micro to macro, and designed based on it. EMG signal, human-computer interaction interface of contact force signal, force interaction mechanism between human and exoskeleton is studied, control strategy of exoskeleton robot is formulated, and Experimental Research on human-computer interaction and robot control is carried out.
Firstly, taking myosin molecular motor as the object, the nanomechanical properties and operation mechanism of the molecular motor are analyzed. According to the cyclic working process of the molecular motor, the movement law of the molecular motor approaching and combining to actin filament under the coupling action of van der Waals force, Casimir force, electrostatic force and Brownian force is explored, and the molecular motor is established. The kinetic model of the cycling process was established by Monte Carlo method. It was found that when the distance between the molecular motor and the filament surface was more than 3 nm, the main forces were Casimir force and electrostatic force, and when the distance was less than 3 nm, van der Waals force and electrostatic force made the molecular motor move to the filament orbit faster. Comparing the effects of these forces, we can see that the electrostatic force is dominant in the process of approaching, and thus clarify the mechanical mechanism of the molecular motor starting to run and muscle contraction, and analyze the key role of calcium ions in muscle contraction. At the same time, we analyze the influence of the spatial potential field of the molecular motor on the stability of muscle fiber structure.
Secondly, a new skeletal muscle mechanics model is constructed by analyzing the collective operation characteristics of molecular motors and using the non-equilibrium statistical mechanics method from microscopic to macroscopic. Firstly, the collective operation mechanism of molecular motors is studied. In order to reflect the N states of a cycle of molecular motors, the Fokker-Planck equation of the probability density of displacement variables is constructed and examined. The mechanical model of active contraction of sarcomere was deduced by considering the spatial structure of sarcomere, the elastic coefficient of molecular motor and the cross-sectional area of sarcomere. The effects of ATP concentration and load on the active contraction force and contraction velocity were analyzed by calculating the probability density distribution of displacement variables. The steady-state relationship between the action potential frequency and the contraction force of sarcomeres was established. Considering the series-parallel interaction of sarcomeres, a skeletal muscle mechanical model based on the collective operation mechanism of molecular motors was established from microscopic to macroscopic. Active contraction force fuses and follows the trend of calcium ion concentration. When the action potential is at its maximum frequency, the muscles contract rigidly. When the ATP concentration is saturated, the maximum isometric contraction force mainly depends on the number of molecular motors, elastic coefficient, muscle cross-sectional area and other physical parameters. This lays a theoretical foundation for the study of the relationship between EMG signal characteristics and muscle strength.
Thirdly, according to the motion characteristics of human lower limb joints, such as wide range of motion, many degrees of freedom and large joint torque, a multi-functional lower limb exoskeleton robot is designed and implemented from the perspective of bionics, and a parallel articulated exoskeleton ankle joint is developed. For walking, the parallel ankle joint can realize the back flexion/plantar flexion of the ankle joint and the inversion/valgus motion with two degrees of freedom. The exoskeleton robot is suitable for the people whose height is between 155 cm and 190 cm, and can adjust the trajectory of the center of gravity of the human body actively to conform to the characteristics of fluctuation. The system has high stability and reliability. The human-computer interaction interface of force-tactile signal, including sensor unit (EMG signal acquisition instrument, interactive force sensor), data acquisition and processing unit, focuses on the study of force interaction mechanism between human and exoskeleton, establishes the dynamic model of exoskeleton robot, and takes human knee joint as the object, carries out the research using the thigh skeletal muscle system. The forward/reverse kinetics model of human knee joint was established to construct the functional relationship between EMG signal characteristic frequency and muscle contraction force and joint torque.
Fourthly, the human-machine interaction experiment and the application of human-machine interface in the active control of exoskeleton robot are carried out. Firstly, the control system of exoskeleton robot is improved and the exoskeleton control strategy is formulated to meet the different rehabilitative training requirements. Secondly, the human-machine interaction experiment is carried out, and the human-exoskeleton interaction is achieved by collecting the EMG signal of thigh muscle. Mutual force is represented by EMG signal, muscle contraction force and joint torque are calculated according to muscle mechanics model, and the reaction torque between muscle active torque and exoskeleton is compared. The experimental results show that the two coincide well, which proves the rationality of the muscle mechanics model. Finally, according to exoskeleton robot control. The passive mode is to complete the training of human lower limbs according to the set gait and angle information. The active mode is to collect the EMG signals of muscles by combining the human-computer interaction interface, predict the required torque of joint motion by using the muscle mechanics model, identify the human motion intention, and according to the prediction letter. It completes the intelligent control of the external skeleton robot, and realizes the active assistance training according to the human body's intention.
【學位授予單位】：上海交通大學
【學位級別】：博士
【學位授予年份】：2012
【分類號】：TH789
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