A modified measure for the Parallel cable driven robots is presented in this paper. These robots have additional advantages compared to other robots and even the Parallel structures, but they are readily exposed to disturbances. The presence of external wrench (Force-Moment) may be the cause of violation against the motion constraint. The stability measure proposes a number between zero and one that could be the criterion for the evaluation of the robot's ability while returning to its original equilibrium which was influenced by external disturbances. To offer a stability measure, Gibbs-Appell equations and acceleration energy are used. robot kinematic and dynamic modeling based on Newton-Euler’s method calculates the measure. To illustrate the capabilities of the proposed measure, a 6 DOF cable robot with six cables is simulated. The results of the two simulations are presented and analyzed. The stability measure is depended to kinematic parameters and also to kinetics parameters as cables tension at the beginning of motion. Therefore using the proposed measure one can better evaluate the stability within the wider range of Parallel cable robots.

Accommodation of mechanism with human being’s physical characteristics creates the possibility of safe and efficient interaction between human being and robot. Regarding the fact that amputation of a limb in human beings causes several mental, economical and social difficulties and problems, need to a substitute limb which has the most efficiency for the person after amputation is a vital need. The cable robots are the kinds of robots that the cable is used instead of rigid link. The cable robots have a simple appearance that some cables connect the motors to the final organ. In this research a robot with cable mover is designed and modeled as a tool in the case of creating movement with the most accordance for an artificial organ below the knee. In addition, in this mechanism some advantages are also considered including creating movement in two axes, its cheapness and lightness. In this research at first a primary design of the artificial organ is presented. The forward and inverse kinematic relations which are dominant on system are explained, in fact you can find different features with kinematic robots like dexterity, global condition, local condition, etc, and finally we study the available workspace for the system. Workspace in cable robots is different from other Parallel robots, in this paper, first description about some methods for finding workspace in cable-driven-robots and then use of force-closure workspace to find workspace for this system are presented.

In this paper, dynamic modeling, optimal path planning and control scheme on a redundant Parallel cable robotis presented. Path planning in Parallel robots necessitates the consideration of robot’s kinematics to discern the singularities in the workspace. Also, dynamics analysis is required to consider actuation constraints. To this end, kinematics and dynamics of cable driven redundant Parallel robot is derived. In this modeling, cables are assumed to be rigid with negligible mass and hence, tension and sagging along the cable are neglected. Next, a sampling-based algorithm upon rapidly-exploring random tree is developed to increase the convergence rate. In this scheme, distance, epochs and safety are considered as optimization constraints. To evaluate the performance of the proposed algorithm in collision avoidance, a number of obstacles have been considered too. Tracking of the planned path has been handled using a feed-forward controller in the presence of obstacles. Regarding the redundancy feature of robot, a redundancy resolution scheme is considered for optimal force distribution. Path planning and control algorithms are implemented on the RoboCab (ARAS Lab.) and experimental results reveal the efficiency of the proposed schemes.

cable-Driven Parallel robot has many advantages. However, the problems of cable collision between each other and environment, the lack of proper structure and non-positive cable tension prevent the spread of them. Therefore, connecting a serial manipulator to mobile platform improves the ability of object manipulation. This paper investigates the multi-objective optimization structure design and comparative study of spatial constrained and suspended cable-driven Parallel robot. Installed serial manipulators possess a full hybrid robot’s features. The workspace volume, kinematic stiffness and sensitivity are three sets of optimization criteria. The workspace volume is calculated by a novel approach of combination constraints to prevent cables colliding with each other, cable collision with moving platform, uncontrollability and singularity of the robot. First, the range of forces and torque reaction of the serial manipulator to moving platform is examined. Then, the evolutionary optimization genetic algorithm is used for the multi-objective optimization of constrained and suspended spatial cable-driven Parallel robot structure to achieve proper Pareto front confrontation. The Pareto front reconciliation of these three criteria will be discussed. The constrained and suspended optimized by the same criteria will be compared in the same conditions. It is confirmed that the constrained structure significantly reduced actuation energy to manipulate a serial robot, supply greater workspace and manipulability. The result of this study used for manufacturing and development of a prototype spatial cable-driven Parallel robot (RoboCab).

In most research on Parallel cable robots, control input energy norm (with two-squared cost function), also known as the least-squares method is widely used, but in addition to the advantages of this method, such as smoothness and differentiable, in the case of the current cable robot, where the cable structure has a physical meaning only in the positive range, using the linear cost function is sufficient in terms of mathematical modeling. With this replacement, without compromising the convexity, the optimization problem on the robot is solved with the low tensile limit and the high rupture limit, and the equal constraint tensile strength of the cables and the moving platform. The simulation results show that while the mentioned the alternative in the cost function does not have a significant effect on solving the optimization problem with numerical methods, the reduction in the average elapsed time to achieve the optimal solution is about 3 times, compared to the analytical method with the two-squared cost function, and is obtained at least 80 times that of numerical methods.

Optimal design of Parallel manipulators is known as a challenging problem especially for cable driven robots. In this paper, optimal design of cable driven redundant Parallel manipulators (CDRPM) is studied in detail. Visual Inspection method is proposed as a systematic design process of the manipulator. A brief review of various design criteria shows that the optimal design of a CDRPM cannot be performed based on single objective. Therefore, a multi objective optimal design problem is formulated in this paper through an overall cost function. Furthermore, a proper weighting selection for the overall cost function is proposed, which can be viewed as a promising method to the open problem of Parallel manipulator design. In order to verify the effectiveness of the proposed method, it is applied on the design of KNTU CDRPM, an eight actuated with six degrees of freedom CDRPM, which is under investigation for possible high speed and wide workspace applications in K.N. Toosi University of Technology. Finally, a combined numerical optimization algorithm is used to find the unique global optimum point. The result shows a significant enhancement in the performance characteristics of the KNTU CDRPM compared to that of the other CDRPMs. Since the proposed method is not restricted to any particular assumption on the objectives and design parameters, it can be used for optimal design of other manipulators.

In this article a method for determining the admissible acceleration of the end-effector is presented for the suspended cable robot in the different points of the workspace. The presented acceleration analysis is different with the dynamic work space. Indeed, the dynamic work space is defined as the set of all end-effector poses satisfying the acceleration conditions. While in the proposed analysis in this paper, the allowable acceleration range of the end-effector in each direction is obtained for any point of the workspace. To this end, after deriving the kinematic equations of the four-cable suspended robot, its dynamic equations are derived using the Lagrange method. Then, on the base of the positive tension constraint in the cables and the torque constraint of the actuators, the obtained equations are simplified to obtain the simple relation between the constrains and the end-effector acceleration in such a way that the lower and upper limit of the admissible acceleration is obtained. Some simulations are done in order to present the admissible acceleration in different point of the workspace. The simulation results show that the acceleration range is in the form of the pyramid with the rhomboid base. So the allowable range of the acceleration is changed in different direction. The results obtained in this paper can be used for online trajectory planning in high speed motion of cable robot.

A new mechanism is presented in this paper for simulating the athlete performance and training the sportsman’s exercises. This mechanism is an autonomous closed loop six degrees of freedom (DOFs) cable suspended robot which eases the implementation of some sport utilities. It cancels the necessity of presence of a sport coach for training the sportsman. Using the proposed robot, it is possible to program the robot for training the athlete limb (arm, leg and etc.) within a predefined trajectory corresponding to his special sport performance. Considering the fact that in many sports a large environmental space needs to be covered by the athlete movement, ordinary robots are not capable to be employed for this application while cable robots are applicable since a large dynamic workspace can be covered by them. Moreover, training the sportsman limb requires a precise movement of the mentioned end-effector on a predefined trajectory. This importance could not be satisfied without using a proper closed loop controlling system since variable external disturbances affects on the end- effector as a result of the weight of the sportsman limb and its dynamic movement. The validity and efficiency of the proposed mechanism in training the athletes’ limb is verified by conducting experimental test on Iran University of Science and Technology (IUST) cable robot (ICaSbot).

cable Parallel robots usually require at least one additional actuator force in addition to degrees of freedom to keep the cables in all directions in the workspace, which solves an optimization problem to determine the cable tensile force. In this paper, a convex optimization problem is formulated on a Parallel cable robot using optimization conditions through the Karush-Kuhn-Tucker theory and the analytical-iteration method to achieve a minimum force vector of actuators that has less computational time and volume. Where the lower and upper limits of the optimization variables are applied, respectively, to ensure that the cables remain in tension and take into account the saturation limit of the actuators or the rupture limit of the cables (whichever is less), and equal constraints that the relationship between actuator force and force are expressed in the moving platform, defined by the force of the actuators as the sum of the basic solution and the homogeneous solution, -located in the null space of the transpose of Jacobin matrix. Comparison of the results of analytical-iterative solution presented in this paper with numerical algorithms of MATLAB software optimization shows that this method is much faster than these algorithms to converge to the optimal response.