Mapping of human arm impedance characteristics in spatial movements (original) (raw)

Characteristics of Human Arm Impedances: A Study on Daily Movement

2014 UKSim-AMSS 16th International Conference on Computer Modelling and Simulation, 2014

This paper presents the impedance characteristics of human arm in daily spatial activity. Human arm is considered as a mass-spring-damper system. The input data in the form of Cartesian position is measured to get dynamic impedance relationship by the motion equation for the mass-springdamper system. Mappings are done by various combinations to observe the nature of the different impedance components during dynamic movement. The significant amount of variation in damping and inertia components are observed in every turning of the arm movement while the stiffness shows the changing behavior throughout the movement. From this study it is known that for this particular movement the arm follows a pattern and same behavior is followed for the repetitions of the movement. The obtained result could be beneficial for the study of upper extremity exoskeleton for human rehabilitation.

Impedance characteristic of the human arm during passive movements

IAES International Journal of Artificial Intelligence, 2023

This paper describes the impedance characteristics of the human arm during passive movement. The arm was moved in the desired trajectory. The motion was actuated by a 1-degree-of-freedom robot system. Trajectories used in the experiment were minimum jerk (the rate of change of acceleration) trajectories, which were found during a human and human cooperative task and optimum for muscle movement. As the muscle is mechanically analogous to a spring-damper system, a second-order equation was considered as the model for arm dynamics. In the model, inertia, stiffness, and damping factor were considered. The impedance parameters were estimated from the position and torque data obtained from the experiment and based on the "Estimation of Parametric Model". It was found that the inertia is almost constant over the operational time. The damping factor and stiffness were high at the starting position and became near zero after 0.4 seconds.

A model of force and impedance in human arm movements

Biological Cybernetics, 2004

This paper describes a simple computational model of joint torque and impedance in human arm movements that can be used to simulate three-dimensional movements of the (redundant) arm or leg and to design the control of robots and human-machine interfaces. This model, based on recent physiological findings, assumes that (1) the central nervous system learns the force and impedance to perform a task successfully in a given stable or unstable dynamic environment and (2) stiffness is linearly related to the magnitude of the joint torque and increased to compensate for environment instability. Comparison with existing data shows that this simple model is able to predict impedance geometry well.

Control of 3D Human Arm Impedance

2013

Humans have an inherent capability of performing highly dexterous and skillful tasks with their arms, involving maintaining posture, movement and interacting with the environment. The latter requires for them to control the dynamic characteristics of the upper limb musculoskeletal system. Inertia, damping and stiffness, a measure of mechanical impedance, gives a strong representation of these characteristics. Many previous studies have shown that the arm posture is a dominant factor for determining the end point impedance in a horizontal plane (transverse plane). The objective of this thesis is to characterize end point impedance of the human arm in the three dimensional (3D) space. Moreover, it investigates and models the control of the arm impedance due to increasing levels of muscle co-contraction. The characterization is done through experimental trials where human subjects maintained arm posture, while perturbed by a robot arm. Moreover, the subjects were asked to control the level of their arm muscles' co-contraction, using visual feedback of their muscles' activation, in order to investigate the effect of the muscle co-contraction on the arm impedance. The results of this study showed a very interesting, anisotropic increase of the arm stiffness due to muscle co-contraction. This can lead to very useful conclusions about the arm biomechanics as well as many implications for human motor control and more specifically the control of arm impedance through muscle co-contraction. The study finds implications for the EMG-based control of robots that physically interact with humans.

Human Arm Impedance: Characterization and Modeling in 3D Space

IEEE/RSJ 2010 International Conference on Intelligent Robots and Systems (IROS), 2010

Human motor control has always acted as an inspiration in both robotic manipulator design and control. In this paper, a modeling approach of anthropomorphism in human arm movements during every-day life tasks is proposed. The approach is not limited to describing static postures of the human arm but is able to model posture transitions, in other words, dynamic arm movements. The method is based on a novel structure of a Dynamic Bayesian Network (DBN) that is constructed using motion capture data. The structure and parameters of the model are learnt from the motion capture data used for training. Once trained, the proposed model can generate new anthropomorphic arm motions. These motions are then used for controlling an anthropomorphic robot arm, while a measure of anthropomorphism is defined and utilized for assessing resulted motion profiles.

Analysis of Driving–Point Mechanical Impedance of the Human Hand Arm System

In this study, the Authors propose the discussion of nonlinearity of the human body's dynamic response. The variables that affect nonlinearity of the human body's dynamic response in the experimental measurements can be distinguished in two categories: intrinsic variables, relating to the individual subjects; and extrinsic variables, relating to the experimental conditions. International Standard 5982 : 2002 gives idealized values for the apparent mass and the seat-to-head transmissibility of seated people exposed to vertical vibration. The values are intended for the development of mechanical models to represent the body. Many mathematical models of the vertical apparent mass of the seated human body are developed. Single and two-degree-of-freedom models obtain a good agreement with experimental seat transmissibility by nonlinear least squares method and Trust-Region algorithm. The comparison between single and two-degree-offreedom models by goodness-of-fit statistics suggests that two-degree-of-freedom model is recommended for best results. . Effects of posture and vibration magnitude on apparent mass and pelvis rotation during exposure to whole-body vertical vibration. Journal of Sound and Vibration, 253 :93-107, 2002. N.J Mansfield and S. Maeda. Comparison of the apparent mass of the seated human measured using random and sinusoidal vibration. Industrial Health, 43:233-240, 2005. Y. Matsumoto and M. J. Griffin. Effect of muscle tension on non-linearities in the apparent masses of seated subjects exposed to vertical to vertical whole-body vibration. Journal of Sound and Vibration, 253:77-92, 2002. Y. Matsumoto and M.J. Griffin. Movement of the upper-body of seated subjects exposed to vertical whole-body vibration at the principal resonance frequency. Journal of Sound and Vibration, 215(4):743-762, 1998. H. Mertens. Nonlinear behavior of sitting human under increasing gravity. Aviation, Space, and Environmental Medicine, 49:287-298, 1978. N. Nawayseh and M.J. Griffin. Non-linear dual-axis biodynamic response to vertical whole-body vibration. Journal of Sound and Vibration, 268:503-523, 2003. N. Nawayseh and M.J. Griffin. Non-linear dual-axis biodynamic response to fore-and-aft wholebody vibration. Journal of Sound and Vibration, 282:831-862, 2005. N. Nawayseh and M.J. Griffin. A model of the vertical apparent mass and the fore-and-aft crossaxis apparent mass of the human body during vertical whole-body vibration. of two dynamic manikins for laboratory testing of seats under whole-body vibration. International Journal of Industrial Ergonomics, 38:457-470, 2008. G.S. Paddan and M.J. Griffin. The transmission of translational seat vibration to the head-i. vertical seat vibration. Journal of Biomechanics, 21(3):191-197, 1988. G.S. Paddan and M.J. Griffin. A review of the transmission of translational seat vibration to the head. Journal of Sound and Vibration, 215(4):863-882, 1998. G.S. Paddan and M.J. Griffin. Evaluation of whole-body vibration in vehicles. Journal of Sound and Vibration, 253(1):195-213, 2002. M.K. Patil and M.S. Palanichamy. A mathematical model of tractor-occupant system with a new seat suspension for minimization of vibration response. Applied Mathematical Modelling, 12(1): 63-71, 1988. Yi Qiu and M.J. Griffin. Modelling the fore-and-aft apparent mass of the human body and the transmissibility of seat backrests. Vehicle System Dynamics, 49(5):703-722, 2011.

Task-oriented impedance adjustments of human arm movements

1999

This paper discusses task-oriented control strategies and their dynamic formation in movements of human arm, with the impedance adjustment as the fundamental control method in its redundant degree-of-freedom (DOF) muscular-skeletal structure. Impedance adjustment mechanisms and dynamic characteristics for the muscularskeletal and spinal reflection systems are described. It is also shown that the impedance adjustment at the joint and muscular levels plays an important role in the manipulation of objects. Dynamic impedance properties (stiffness and viscosity) of the actuating structure, together with the equilibrium trajectory profile of the structure, is defined to be the expression of the motion skill. Then, a task-oriented iterative impedance adjusting algorithm based on Variant Calculus is proposed, and simulation examples on a three-DOF planar arm are presented to show that the task-oriented motion skills can be formed under naturally specified simple objective functions.

Driving-point mechanical impedance of the human hand-arm system: synthesis and model development

Journal of Sound and Vibration, 1995

A synthesis of the measured values of human male hand-arm impedance characteristics reported in the literature has been performed. The driving-point mechanical impedance data of the human hand-arm grasping a vibrating handle has been compared to highlight the various similarities and differences among the data. Unexplained differences among the results of various studies, conducted independently under nominally equivalent measurement conditions, led to the exclusion of outliers from the analysis. The most probable values of impedance phase and magnitude are defined by lower and upper envelopes of the mean values of the accepted data sets. The mean of the data sets, together with the smoothened envelopes, are used to define the target and range of idealized values of the Xh , Yh and Zh components of impedance in the 10-1000 Hz frequency range. A pooling of results from different studies suggests that there is a small dependence of the Xh component of impedance magnitude on the hand grip forces. The dependence of the phase of the corresponding impedance component on the hand grip force, however, is insignificant. There is insufficient data from independent sources to establish a dependence of other components of impedance on the hand grip and thrust forces. A four-degrees-of-freedom, lumped parameter model is derived to fit the target impedance magnitude and phase values using a constrained optimization algorithm. The predicted values correlate well with the target values in the selected frequency range.

Impedance characteristics of a neuromusculoskeletal model of the human arm I. Posture control

Biological Cybernetics, 1999

The mechanical impedance of neuromusculoskeletal models of the human arm is studied in this paper. The model analysis provides a better understanding of the contributions of possible intrinsic and re¯exive components of arm impedance, makes clear the limitations of second-order mass-viscosity-stiness models and reveals possible task eects on the impedance. The musculoskeletal model describes planar movements of the upper arm and forearm, which are moved by six lumped muscles with nonlinear dynamics. The motor control system is represented by a neural network which combines feedforward and feedback control. It is optimized for the control of movements or for posture control in the presence of external forces. The achieved impedance characteristics depend on the conditions during the learning process. In particular, the impedance is adapted in a suitable way to the frequency content and direction of external forces acting on the hand during an isometric task. The impedance characteristics of a model, which is optimized for movement control, are similar to experimental data in the literature. The achieved stiness is, to a large extent, re¯exively determined whereas the approximated viscosity is primarily due to intrinsic attributes. It is argued that usually applied Hill-type muscle models do not properly represent intrinsic muscle stiness.

Impedance characteristic of human arm for cooperative robot

제어로봇시스템학회 국제학술대회 논문집, 2002

Control systems for cooperative robots should be designed to work imitating human characteristics. In this study, we tried to investigate the impedance characteristic of human arm in a cooperative task. Human arm was moved in a desired trajectory. The motion was actuated by a 1 degree-of-freedom robot system. Trajectories used in the experiment were minimum jerk (the rate of change of acceleration) trajectories, which was found during human and human cooperative task and optimum for muscle movement. As the muscle is mechanically analogous to a spring-damper system, a second-order equation was considered as the model for arm dynamics. In the model, inertia, stiffness and damping factor were considered. The impedance parameter was estimated from the position and torque data obtained from the experiment and based on the "Estimation of Parametric Model". It was found that the inertia is almost constant over the operational time. The damping factor and stiffness were high at the starting position and became near to zero after 0.4 second. The EMG (electromyography) response of elbow muscles during the movements was also examined.