Dynamic interaction-oriented subject's limb time-varying stiffness identification method and device

A dynamic interaction-oriented subject's limb time-varying stiffness identification method, comprising the following steps:

• in a random small-perturbation motion environment, a subject keeping a limb posture unchanged, and by changing states of muscles, a combination of a subject's limb displacement and a measured force data or a combination of an angle and a measured torque data being collected by a data acquisition system;
• based on a restoring force/torque expression with substituted time-varying impedance parameters and an expression of a dynamic interaction force/torque expanded by a basis function, and according to the combination of the subject's limb displacement and the measured force data or the combination of the angle and the measured torque data, iterative identification of the dynamic interaction force/torque and a restoring force/torque being performed by using parameters of time-varying dynamics;
• a linear coefficient matrix and the dynamic interaction force/torque obtained in the iterative identification of the parameters being utilized to calculate a time-varying stiffness of the subject's limb according to the restoring force/torque expression with the substituted time-varying impedance parameters;
• wherein the method for obtaining the restoring force/torque expression with the substituted time-varying impedance parameters comprises the following steps:
• according to time-varying impedance characteristics of the subject's limb, a second-order impedance model being utilized to construct a time-varying dynamic model of the subject's limb;
• a linear parameter varying method being adopted to construct a time-varying damping parameter of the subject's limb and the time-varying stiffness parameter of the subject's limb in the time-varying dynamic model of the subject's limb as a weighted sum of a function with a scheduling variable as an independent variable, and the restoring force/torque being transformed to obtain the restoring force/torque expression with the substituted time-varying impedance parameters;
• wherein the dynamic interaction force/torque is the scheduling variable;
• the method for obtaining the expression of the dynamic interaction force/torque expanded by the basis function is:
• the dynamic interaction force/torque being expressed by an expansion of the basis function, and a basis function sequence in a perturbation duration interval and weights of the basis function being utilized to represent the dynamic interaction force/torque,
• wherein the data acquisition system comprises a collaborative robotic arm, reflective markers, an optical motion capture system, a six-dimensional force/torque sensor and a display, wherein
• a tool end of the collaborative robotic arm is fixedly provided with the reflective markers, and is connected with the six-dimensional force/torque sensor, which is fixedly connected to an endpoint/joint of the limb when in use;
• the optical motion capture system is configured to collect a three-dimensional position of the reflective markers and obtain the displacement/angle information of the subject's limb;
• the reflective markers are configured to record the limb posture;
• the collaborative robotic arm is configured to construct the random small-perturbation motion environment in a three-dimensional space;
• the six-dimensional force/torque sensor is configured to collect a measured force/torque information between the subject's limb and the tool end of the robotic arm;
• the display provides the subject with visual feedback of real-time data from the six-dimensional force/torque sensor during dynamic interactions.