Fault Tolerant Planning And Experiment Of Variable Geometry Truss Manipulator

Variable Geometry Truss(VGT),as a kind of high-rigidity,lightweight and flexible hyper-redundant manipulator,has a wide application prospect in space operation.When the variable geometry truss manipulator is engaged in the complex task in the space environment full of cosmic rays,the joints are prone to failure.And it is very costly to repair or replace the faulty module manually,so it is very important to study the fault-tolerant of the variable geometry truss manipulator.Therefore,this thesis studies the problem of the original pose control in the case of a single-joint fault of a variable-geometry truss manipulator.The main contents are as follows:1.For the problem that the encoder information may be inaccurate after the fault,the excitation measurement method is used to traverse each truss element.Fault is determined by comparing the pose errors between the calculated and measurement under certain instructions for each truss element.And the position and length of the fault joint is given by the inverse kinematics algorithm.The experimental results show that this method can realize fault location after faults occur.2.A fault-tolerant planning algorithm based on kinematic reconfiguration is proposed to solve the pose control problem after failure.The unit is degenerated to a fixed truss by introducing the constraint that lengths of the drives are equal in the faulty unit.The kinematics model is reconstructed according to the symmetry.The lengths of the drives of each normal unit are obtained by multi-section analytical inverse kinematics algorithm.The simulation results show that the algorithm can realize the posture control of the single-joint-failure variable geometry truss manipulator.3.According to the requirements of variable geometry truss arm system,the software and hardware platform is designed and realized the automatic target grabbing under the unobstructed space.Under this platform,the target grabbing experiment under single joint fault is carried out,which proves the fault tolerance proposed in this paper.The planning algorithm can realize the original pose control requirement in the obstacle-free space of the single-joint variable geometry truss manipulator.In this thesis,a fault-tolerant planning algorithm based on kinematic reconfiguration is proposed to solve the fault-tolerant problem of single-joint-fault variable geometry truss manipulator.The position and orientation control of the fault manipulator under obstacle-free space is realized,which provides a theoretical basis for the space operation task in case of failure of the manipulator and reduces the maintenance costs of the manipulator.