In this paper, an algorithm is proposed to improve the Maximum Load Carrying Capacity (MLCC) of flexible robot manipulators. The maximum allowable Load which can be achieved by a flexible manipulator along a given trajectory is limited by the joints' actuator Capacity and the end effector accuracy constraint. In an open-loop approach, the end effectors deviation from the predeffned path is significant and the accuracy constraint restrains the maximum payLoad before actuators go into saturation mode. By using a controller, the accuracy of tracking will improve. The actuator constraint is not a major concern and, therefore, the full power of the actuators, which leads to an increase in the Maximum Load Carrying Capacity, can be used. In this case, the controller can play an important role in improving the maximum payLoad, so a robust controller is designed. However, the control strategy requires measurement of the elastic variables' velocity, which is not conveniently measurable. So, a nonlinear observer is designed to estimate these variables. A stability analysis of the proposed controller and state observer is performed on the basis of the Lyapunov Direct Method. In order to verify the effectiveness of the presented method, simulation is done for a two link flexible manipulator. The obtained maximum payLoad for open and closed-loop cases is compared, and the superiority of the method is illustrated.

The calculation of the Load Carrying Capacity of variable thickness circular plates subjected to arbitrary rotational symmetric Loading is presented. The analysis considers plate materials that obey either the square or the Tresca yield criterion. By using upper and lower bound theorems of limit analysis, corresponding estimations for the Load Carrying Capacity of the plate are obtained. It is shown that these two bounds are identical. Therefore, the obtained solution would represent the exact amount of the Load Carrying Capacity of the variable thickness circular plate. Finally, in order to obtain solutions for some special cases, plates having step changes in thickness and those with linear thickness variation are considered and corresponding results are illustrated.

In this paper a performance analysis is presented for a cable-suspended parallel manipulator. Experimental results from some first tests are presented and discussed to validate the theoretical calculation of Load Carrying Capacity. The Load Carrying Capacity during a given trajectory is obtained. This computational technique is tested on a typical planar cable suspended manipulator. The experiment is performed to compare the calculated maximum Load with the actual Carrying payLoad on the path chosen for the comparison.

In this paper, a computational method for obtaining the maximum Dynamic Load Carrying Capacity (DLCC) for the 6-UPS Stewart platform manipulator is developed. In this paper, the manipulator is assumed to be non-rigid and the joint actuator torque Capacity and accuracy of motion are considered major limiting factors in determining the maximum payLoad. The maximum dynamic payLoad Carrying Capacity of the manipulator is established, while the dynamic model of a typical hydraulic actuator system is used in the joint actuator force Capacity for a given trajectory. The flexibility of the manipulator is assumed to be eventuated from the manipulator's joints flexibility. According to the high complexity of the dynamic equations system of the flexible joints parallel manipulators, the effects of the flexibility of the prismatic joints are considered in a static situation to show the considerable effects of the joint's flexibility on the motion accuracy of the 6UPS-Stewart platform. This method can be used for determining the maximum dynamic payLoad, which acts as an end-effector for the mechanical design of the manipulator and the optimized selection of the actuator, such as machine tools, based on the hexapod mechanism.

This paper proposes a control strategy for a cable-suspended robot based on sliding mode approach (SMC) which is faced to external disturbances and parametric uncertainties. This control algorithm is based on Lyapunov technique which is able to provide the stability of the end-effecter during tracking a desired path with an acceptable precision. The main contribution of the paper is to calculate the Dynamic Load Carrying Capacity (DLCC) of a spatial cable robot while tracking a desired trajectory based on SMC algorithm. In finale, the efficiency of the proposed method is illustrated by performing some simulation studies on the ICaSbot (IUST Cable Suspended Robot) which supports 6 DOFs using six cables. Simulation and experimental results confirm the validity of the authors’ claim corresponding to the accurate tracking capability of the proposed control, its robustness and its capability toward DLCC calculation.