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.

Background: Along with rapid economic growth, many natural regions, meadows, farms, etc. have been converted into unbridled urban areas. Urban development converts natural areas into districts full of buildings leading to disrupted ecological balance of the ecosystem. The CARRYING CAPACITY (CC) of urban ecosystems needs to be estimated because they require large amounts of materials and energy as well as the ability of pollutant absorption in a small location. The amount of material and energy used in cities may be more than of that provided by urban CC. High consumption rate is associated with high levels of contamination that transcends the UCC. Therefore, the CC of the urban environment and its population CAPACITY must be evaluated for urban development planning. Materials and Methods: In this study, UCC LOAD number within the pressure-state-impact-response (PSIR) framework and 20 indicators were used to evaluate the CC and pressure on the urban ecosystem of Semnan. Results: According to the results, the LOAD number in the district 1 was equal to 180. 05with a low to moderate pressure on the urban ecosystem. The LOAD numbers in districts 2 and 3 were respectively 230. 41 and 272. 86 imposing a moderate to high pressure on urban ecosystem. Conclusions: Because of the greater population density in the District 3, materials and energy consumption and waste production was higher leading to a higher pressure on the urban ecosystem.

This paper presents an indirect method for computing optimal trajectory, subject to robot DYNAMICs, flexibilities and actuator constraints. One key-issue that arises from mechanism flexibility is finding the DYNAMIC LOAD CARRYING CAPACITY ((DLCC)). The motion planning problem is first formulated as an optimization problem, and then solved using Pontryagin's minimum principle. The basic problem is converted to the Two-Point Boundary Value Problem (TPBVP), which includes joint flexibility. Some examples are employed to compare three models, DYNAMIC, flexible joint, and rigid. The results illustrate the effectiveness of this indirect method.

In this paper, according to high LOAD CAPACITY and rather large workspace characteristics of cable driven robots (CDRs), maximum DYNAMIC LOAD CARRYING CAPACITY ((DLCC)) between two given end points in the workspace along with optimal trajectory is obtained. In order to find (DLCC) of CDRs, joint actuator torque and workspace of the robot constraints concerning to non-negative tension in cables are considered. The problem is formulated as a trajectory optimization problem, which is fundamentally a constrained nonlinear optimization problem. Then the iterative linear programming (ILP) method is used to solve the optimization problem. Finally, a numerical example involving a 6 DOF CDR is presented and results are discussed.

In this paper, finding DYNAMIC LOAD CARRYING CAPACITY ((DLCC)) of flexible link manipulators in point to-point motion was formulated as an optimal control problem. The finite element method was employed for modelling and deriving the DYNAMIC equations of the system. The study employed indirect solution of optimal control for system motion planning. Due to offline nature of the method, many difficulties such system nonlinearities and all types of constraints can be catered for and implemented easily. The application of Pontryagin’s minimum principle to this problem was resulted in a standard two-point boundary value problem (TPBVP), solved numerically. Then, the formulation was developed to find the maximum payLOAD and corresponding optimal path. The main advantage of the proposed method is that the various optimal trajectories can be obtained with different characteristics and different maximum payLOADs. Therefore, the designer can select a suitable path among the numerous optimal paths. In order to verify the effectiveness of the method, a simulation study considering a two-link flexible manipulator was presented in details.

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.

This paper presents the investigation of general formulation and numerical solution of the DYNAMIC LOAD CARRYING CAPACITY ((DLCC)) of flexible link manipulator. The proposed method is based on open loop optimal control problem. A two point boundary value problem (TPBVP) is taken from the Pontryagin's minimum principle. The indirect approach is employed to derive optimality conditions. The system’s DYNAMICs equation of motion is obtained from Gibbs-Appell (G-A) formulation and assumed mode method (AMM). Elastic properties of the links are modeled according to the assumption of Timoshenko beam theory (TBT) and its associated mode shapes. As TBT is more accurate compared with the Euler-Bernoulli beam theory, it is utilized for mathematical modeling of flexible links. The main contribution of the paper is to calculate the maximum allowable LOAD of a flexible link robot while an optimal trajectory is provided. Finally, the result of the simulation and experimental platform are compared for a two-link flexible arm to verify the introduced technique. The efficiency of the proposed method is illustrated by performing some simulation studies on the IUST flexible link manipulator. Simulation and experimental results confirm the validity of the claimed capability for controlling point-to-point motion of the proposed method and its application toward (DLCC) calculation.