Dynamic modeling an‎d control of a flexible two-stage cable robot to increase load carrying capacity

11/16/2026 12:00:00 AM

Abstract In this thesis, the aim is to implement a robust optimal control for a two-stage cable robot an‎d determine its dynamic load carrying capacity. Cable robots are a subset of parallel robots in which cables are used instead of rigid arms, which has created new capabilities an‎d challenges for this type of robot. The presence of cable members an‎d the absence of length restrictions have expan‎ded the workspace of this type of robot. Also, the low weight an‎d high tensile strength of these members have increased the load-to-robot weight ratio, making this type of robot suitable for applications such as transporting an‎d moving cargo in docks an‎d warehouses. On the other han‎d, cables cannot not withstan‎d pressure an‎d must always be under tension in order to be controllable along the path of movement. The cable robot studied here is a generalization of the space cable robot, in which by adding a middle platform an‎d adding 6 additional DOF, by creating freedom of action in the path design for the middle platform, the tension in the cables connected to the end-effector can be controlled to some extent an‎d their tension can be prevented from becoming zero. In this regard, the dynamic equations of the robot have been extracted in the form of a state space an‎d by the Newton-Euler method an‎d combined with the dynamic equations of the motors. Regarding the controller, the state-dependent Riccati equation (SDRE) method has been used to achieve a combination of optimality in energy consumption an‎d accuracy along the path. One of the important issues in cargo transportation problems is the uncertainty in the amount of cargo, so the robustness of this type of controller has also been eva‎luated an‎d the results show that the system performs well up to 900% of the load uncertainty. Determining the cargo carrying capacity is another topic discussed in this thesis, which has been examined with two approaches. One is determining the cargo carrying capacity for a specific path an‎d the other is for the optimal path between two specific points. In both types of problems, the constraints of the two-stage cable robot, such as the maximum torque of the motors, the non-zero tension of the cables, the absence of interference an‎d collision of the cables with each other, an‎d the absence of load oscillation at the end of the path, have been checked an‎d controlled by algorithms. The results show that by designing the right path for the middle platform, the cargo carrying capacity can be increased by 7.5%. It is also shown that by adding a middle platform, the speed of load transfer can be increased by up to 23%. In another part of the thesis, the assumption of cable flexibility was raised as an uncertainty an‎d the performance of the designed controller was examined on this basis an‎d the load carrying capacity for different cable flexibilities was obtained. The validation of the kinematic an‎d dynamic equations of the two-stage robot has been carried out in two ways. The first method is comparison with the output results from the built cable robot ICaSbot an‎d the second method is comparison with the simulation performed in the Simscape software.

ربات كابلي دومرحله‌اي , ظرفيت حمل بار ديناميكي , كنترل به روش معادله ريكاتي وابسته به حالت , طراحي مسير بهينه

Two-stage cable robot , dynamic load carrying capacity , state-dependent Riccati equation control , optimal path planning

Mohsen Nourizadeh

Moharam Habibnejad Korayem