| In recent years,with the continuous development of robot design and technology,the application of robot is gradually facing to the unknown and complex working environment,and its movement and operation mode is also gradually expanded from a single design to a variety of mode integration and composite.Functional integration,self-reconfigurable and other new design methods are constantly proposed by researchers to improve the ability of robots to perform complex tasks.However,in the design process,there are also some problems to be solved,such as the integration method of multiple functional modes of the robot,and the corresponding mode switching.In addition,if the robot is multi-functional integration,the kinematic chain structure often has more actuation joints and rods.Therefore,how to design and optimize the stack configuration of the robot when it is not working,so as to improve the convenience of transportation and carrying,is another important issue in the mechanism design level.Based on the basis of the robot to realize the kinematic chains with deployable characteristics,and multiple kinematic chains and operation objects can be treated as a parallel mechanism of topological form,the design method of a class of multi-operation robot mechanisms with deployable characteristic are proposed.Then,the configuration design is carried out for the realization of multi-operation mechanism and the integration of movement and operation functions,and the exploratory research is carried out on the configuration design,function integration and mode switching methods of typical mechanisms.Specific research contents are as follows:(1)Deployable design of kinematic chain.In order to obtain the internal relationship between deployable and operation characteristics of kinematic chain,the concepts of folding factor and root of chains are put forward based on the motion form and connection characteristics of the joint in the kinematic chain.The deployable conditions of kinematic chains are proposed.At the same time,considering the size limitation of the stack region,the configuration design method of kinematic chain realization with both deployable and operation is obtained.This kind of chains can be folded in the specified area in the non-working state,and each rod is located in the same plane,so that the mechanism has a small occupied volume in the non-working state.During the work,the chains can be expanded to complete different operation modes for the operation object.(2)Configuration design of multi-operation mode robot mechanism with deployable characteristics.Using multiple chains can form a parallel mechanism topology by combined with an operation object,a combination method of deployable kinematic chain and operation objects can change the topology form of mechanism according to the operation task is proposed.To propose this method,the mapping relationship between the DOF realized by the operation mode and the operation object is carried out based on chain decomposition and platform decomposition.The robot mechanism formed by multiple deployable kinematic chains is called multi-operation robot mechanism with deployable characteristic.This kind of mechanism can realize different operation modes of the mechanism to the operation object by connecting and releasing the chains and the operation object.(3)Design and analysis of a typical mechanism with variable operation performance.In order to realize the performance reconstruction of the mechanism to the operation object,and to solve the problem of the output performance simplification of the mechanism,a multi-operation mode deployable robot mechanism with four deployable kinematic chains is proposed.The chain structures are respectively RPRR,RPRRR,RPRRR and RPRR.Each of the three different chains is connected with the object as a group to form different topological forms of parallel mechanisms,and the operation mode of 2R1 T is realized for the operation object.Due to the different structure of the kinematic chain,the performance of the chain group to the operation object is different.According to the performance indexes of the task workspace of different parallel mechanisms,the working mode and chains switching method of the mechanism are proposed to meet the specific task requirements,and the task trajectory planning is analyzed and verified.(4)Design and analysis of a typical mechanism with symmetrical operation performance.In order to solve the problem that the operation of the parallel mechanism is limited by the singularity configuration,a multi-operation mode deployable robot mechanism with symmetrical structure and operation performance is proposed based on the design goal of achieving continuous high operation performance output.The kinematics and Jacobian matrix of the mechanism are established and solved,and the parameter expression of the mechanism with singularity configuration is obtained.According to the fact that Type-I singularity is the key limiting factor of the large rotation angle output of the mechanism,the corresponding switching strategy and trajectory planning are carried out.During the switching process,the numerical simulation and interpolation of joint trajectory based on decomposed motion control are carried out by using pseudo inverse matrix.Finally,the mechanism completes the switch between the execution chains and the chains to be executed,so that the mechanism can avoid the singularity and realize the continuous operation of the operation object.(5)Design and analysis of a typical mechanism with the integration of mobile and operational functions.To realize the robot with the complex function of mobile operation,a leg and arm function switching joint is designed and arranged at the end of the deployable kinematic chain.The kinematics models of the robot in different modes are established.In order to obtain the operation performance of robot in operation mode,the mechanics and corresponding dynamics are analyzed and calculated.At the same time,through the establishment of the dynamic model in the operation mode,the coupling dynamics relationship between the supporting kinematic chain and the operation kinematic chain is obtained.Based on the force maneuverability evaluation index,the posture reduction optimization calculation of the robot in the operation mode is carried out,and the operation ability of the robot is verified by simulation analysis.(6)Multi-mode switching planning and simulation experiment.In order to make a better mode switching plan for the robot,the working mode of the robot is divided into three modes.The first mode is the deployable and extension process,the second mode is the standing and moving process,and the third mode is the supporting operation process.The initial configuration of each mode is defined,and the mechanism can switch between modes by moving to the specified configuration.In the first mode,the step function which is easy to control is used to design the motion sequence of the actuation joint.For the second mode,the main problem is to realize the walking mode of the robot after standing.The gait planning is carried out in the way of crawling gait,and the forward direction gait planning is in the form of compound cycloid,and the motion curves of each actuation joint of the robot are obtained.In the third mode,the key problem is the modeling and solving of inverse kinematics.Based on the terminal operation trajectory of the robot,the inverse kinematics model including the four DOFs operation chain,the inverse kinematics model of the parallel mechanism composed of three chains and the ground.Based on the established model,the task trajectory planning of the mechanism in the third mode is completed.According to the above theoretical design,MATLAB is used to carry out simulation verification.The calculated actual end trajectory curve,expected end trajectory and tracking error are obtained.The maximum tracking error is 0.6mm.At the same time,the ADAMS is used to complete the simulation of robot movement and switching process in each mode.The results provided a strong theoretical basis for the subsequent prototype test of the mechanism.(7)Prototype test of typical movement and mode switching.Finally,the structure design scheme and control system of the robot prototype with the integration of movement and operation functions are proposed,and the movement debugging of the prototype is carried out.In the debugging process,the track of the end of the kinematic chain is calculated and verified when the standpoint is moved and adjusted,and the expected motion of the track of the end of the kinematic chain is realized.Based on the theory and simulation results,the prototype experiments of the robot are carried out,including the working process of folding and extension mode,quadruped movement mode,operation mode,and the switching between each mode.The experimental results show that the prototype of the designed robot can run and switch smoothly in the predetermined mode planning,which proves the feasibility and correctness of the design method and mode switching planning of this kind of robot. |
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