Manipulation Compliance And Safety Technology Of Humanoid Rehabilitation Robot

The rehabilitation works for severely disabled people have brought heavy load for the families and society in recent years.The humanoid rehabilitation robots which can imitate nursing workers to grasp human limb to accomplish rehabilitation works are capable of rehabilitation works that are repetitive and time-consuming,and the robots can also be applied in both upper limbs and lower limbs,which have a wide application prospect.Different from industrial robots,the compliance and safety of manipulation are the requirements that must be met.On account that physical parameters of limbs in different patients have a wide range of variation,the manipulation works applied on human limb by the robot should conform to physical structure and kinematic laws of human body,therefore the research on compliant manipulation based on human physical structure is able to reduce or eliminate redundant force applied on human limb during rehabilitation process.The human limb is formed by muscle,skin,bone and other tissues,which is essentially different from mental parts manipulated by industrial robots.For the safety of patients,the excessive grasping stress and accident drop should be prohibited during rehabilitation works,therefore the research on manipulation safety is of great significance for the application of humanoid rehabilitation robots.In the respect of manipulation compliance,first of all,the manipulation state is divided into optimized manipulation state and forced manipulative state according to the redundant force applied on human limb in this paper.Taking the manipulation of upper limb for example,static manipulation theory and dynamic manipulation theory is proposed for the calculation of optimized manipulative force in optimized manipulation state.For static manipulation theory,a kinematic model which is based on physical structure is established,and coordinate transformation matrices are proposed via D-H method.The static optimized manipulative force which conforms to the gesture of human limb is calculated according to static equilibrium conditions when the limb is manipulated in optimized manipulation state.The experiment results show that the static manipulation theory provides theoretical reference for rehabilitation robots.For dynamic manipulation theory,the movement parameters,which include gesture,angular velocity and angular acceleration of the limbs should be obtained in advance.The discrete parameter sets which is corresponding to time set are obtained from the movement parameters,and then the dynamic optimized manipulative force set is obtained through Lagrangian dynamic equations.In simulation and experiment verification,all the results coincide well with theoretical outcomes,which implies the accuracy and feasibility of the proposed dynamic manipulation theory.The manipulation safety is divided into safety and reliability in the rehabilitation process and safety of human limb.Aimed at providing reference on the configuration of phalanxes to avoid accident limb drop from gripper,the grasping safety and reliability of a two-finger two-joint gripper is studied.For the calculation of finger force,a finite element based simplified calculation method is provided.On account the complexity of human limb structure,the calculation method is verified by a simplified limb model.The research on the safety of human limb puts the emphases on normal stress and shearing stress applied on human soft tissue in rehabilitation process.A 3-d model of human limb is established and optimized by medical imageology and reverse engineering software,and stress data of human limb is obtained from finite element simulation software.The analysis of stress data estimates the safety of soft tissues of human limb in rehabilitation procedure,and reveals relationship between the stress and limb gesture,which can provide theoretical guidance for the choose of limb gesture and application of rehabilitation robots.