Despite model-based approaches are capable of providing acceptable performance, but they require complex dynamics modeling, which make them difficult to apply. To overcome this problem, a time-delay learning-based controller as a model-free approach is proposed for fully-constrained cable-driven parallel robots (CDPRs) considering the positive cable force constraints and actuator limitations. The proposed method uses the memory of control effort as a learning element to linearize the system. In addition, using a saturation function in control law has provided the opportunity to ensure all the cables are bounded and remain in tension, to guarantee both the positive cable forces and actuator limitation. Moreover, in the proposed method, we are able to eliminate the requirement of measurement of the task variables, which is very costly by using expensive external positioning measurement systems. Finally, a …

One of the most challenging issues in adaptive control of robot manipulators with kinematic uncertainties is requirement of the inverse of Jacobian matrix in regressor form. This requirement is inevitable in the case of the control of parallel robots, whose dynamic equations are written directly in the task space. In this paper, an adaptive controller is designed for parallel robots based on representation of Jacobian matrix in regressor form, such that asymptotic trajectory tracking is ensured. The main idea is separation of determinant and adjugate of Jacobian matrix and then organize new regressor forms. Simulation and experimental results on a 2--DOF R\underline{P}R and 3--DOF redundant cable driven robot, verify promising performance of the proposed methods.

Concerning the lack of knowledge about non- linearity and uncertainties existing in the cable-driven robot models, an intelligent controller is proposed in this paper to overcome the lack of knowledge. Brain Emotional Learning is one of the bio-inspired algorithms which mimics the emotional part of the mammals’ brain. Not only does the Brain Emotional Learning Based Intelligent Controller (BELBIC) enable us to reach quick adaptation and robustness, but the computations are also very efficient. By defining the BELBIC learning functions with saturation functions, it is shown that the need to calculate the Jacobian matrix and forward kinematics in the feedback loop is eliminated, while guaranteeing positive tensions to the robot. The performance of the proposed method is examined by experiments, and results show that BELBIC can perform well in terms of tracking error.

In this paper, we investigate the challenges of controlling the ARAS-Diamond robot for robotic-assisted eye surgery adjustment

Known for their lower costs and numerous applications, cable robots are an attractive research field in robotic community. However, considering the fact that they require an accurate installation procedure and calibration routine, they have not yet found their true place in real-world applications. This paper aims to propose a new controller strategy that requires no meticulous calibration and installation procedures and can handle the uncertainties induced as a result of that. It is well known that kinematic uncertainties can lead to loose cables when one deals with a redundantly actuated robot. The control methodology presented in this paper is a simple yet powerful controller based on wave-based theory that can handle the aforementioned loosened cables

In this paper, we derive the dynamic formulation of a deployable cable-driven robot that considers models of the actuator and power transmission systems, and we investigate the challenges of structural uncertainty. To accommodate the inherent uncertainty of the system, we propose a proper control topology based on a cascade structure. The inner loop of the structure controls the cable forces, and the outer loop tracks the precise position of the robot’s end-effector. For the design of the outer loop controller, we propose a robust sliding mode controller with a stability analysis that is based on the Lyapunov direct method. The main contribution of this paper is to analyze the stability of the system as a whole considering both the inner and outer loop controllers. Finally, in order to illustrate the performance of the proposed controller, we present the results of an experiment on a deployable suspended cable-driven robot, which shows the effectiveness of the proposed controller in the presence of the inherent uncertainties of the system.

Fast-tracking of reference trajectory and performance improvement in
the presence of dynamic and kinematic uncertainties is of paramount
importance in all robotic applications. This matter is even more
important in the case of cable-driven parallel robots due to the flexibility
of the cables. Furthermore, cables are limited in the sense that they can
only apply tensile forces, for this reason, feedback control of such robots
becomes more challenging than conventional parallel robots. To address
these requirements for a suspended cable-driven parallel robot, in this
paper a novel adaptive fast terminal sliding mode controller is proposed
and then the stability of the closed-loop system is proven. In the proposed
controller, a nonlinear term as a fractional power term is used to
guarantee the convergent response at a finite time. At last, to show the
effectiveness of the proposed controller in tracking the reference
trajectory, simulations and the required experimental implementation is

performed on a suspended cable-driven robot. This robot, named ARAS-
CAM, has three degrees of transmission freedom. The obtained results

confirm the suitable performance of this method for cable robots.

Despite being vastly investigated for underactuated
serial robots, there is less attention paid to controller design of
underactuated parallel robots in the literature. This paper studies
regulation of an underactuated planar parallel cable-driven robot
with three degrees of freedom. First, kinematic and dynamic
equations of the robot are derived, then equilibrium points of
the robot are investigated. By analyzing dynamics of the under–
constrained robot, it is shown that zero dynamic is oscillatory, thus a control law is proposed by a composition of damping injection and sliding mode control. One of the greatest advantages
of the proposed controller is that after convergence of the robot to the desired point, which is proven by Lyapunov theorem, it is chattering free. Finally, simulation results shows the effectiveness
of the controller in practice.

Sagging of the conductor in transmission line has a vital role in the safety, reliability and efficiency of power transmission. Transmission lines must be designed to guarantee the maximum static loading capacity. This is done by maintaining the minimum vertical clearance between the cables and the ground. However, the increase of the cable length between two tower, leads to the high cost of material and electrical energy loss, as well as increasing the possibility of intervention. On the other hand, reducing the line sagging induces high tension in the conductor, which may lead to damage of the conductor. To assure a safety sagging profile, an inspection is essential at the establishment and maintainance of the power transmission lines. In this paper firstly the mathematical formulation of long and heavy cables are developed. Then an image processing method is applied for inspection of cable sagging. To investigate the method a reconfigurable experimental setup is designed to provide various sagging profiles and the sagging profile is extracted via image processing and the result is compared to that of analytical method.

Cable driven parallel manipulator are known by their low costs and numerous applications. However despite of all research interests and developed methods they are not yet vastly used in action. The reason for this, is their limiting requirements for accurate assembly and installation process. The main goal of this paper is to propose a suitable control method by which the robot could appropriately be controlled, requiring no accurate calibrations or precise sensors. As it is well known, uncertainty in kinematics equations can lead to loose cables in redundant robots controlled through joint space controllers. In this paper a simple but very effective joint space controller is proposed that addresses the problem of loose cables by a wave based control method by employing a novel force feedback scheme. Indeed, a new conceptual framework for controlling deployable cable driven parallel manipulators is introduced by which such robots are greatly empowered at real-world scenarios. Finally, the performance of the proposed controller and its effectiveness is verified through some practical experiments showing that the proposed controller outperforms conventional cascade topologies in terms of much smoother tracking performance.

Adding nonholonomic constraints in parallel manipulators, allows reduction of the actuated-joint number without affecting the reachable workspace. This principle applies to wrist robot in some underactuated designs. This paper studies steady state motion control for an nS-2SPU underactuated parallel wrist robot. First, a suitable Euler angles representation is selected and a new method for forward kinematic problem without extra sensor is proposed. Next, differential kinematics of the robot is analyzed considering first order nonholonomic constraint on angular velocity of the robot. By some manipulations, the derived equations are transformed into chain form, and a hierarchical sliding mode controller is designed for the system. Closed-loop performance of the proposed controller is compared to that of a traditional controller reported in the literature through simulations.

Recently haptic devices are increasingly used in industry and research. As their applications become widespread, their design is needed to be more efficient. At design stage, determinant features of haptic devices such as rigidity, force bandwidth, accuracy etc. must be considered and improved. Structurally, parallel mechanisms (PMs) are appropriate candidates for haptic devices. Due to multi legged structure of PMs and their grounded motors, inertia and stiffness feautures of them are desirable and it also made them popular for applications that require high mechanical transparency. Spherical kinematics (two rotational and one translational motion, 2R-T) is a very common type of motion in haptic devices that is also capable of general rendering. In this paper, several 3-DOF 2R-T PMs are synthesized for haptic applications by means of the screw theory. All of these mechanisms have center of motion (CM) which is a key property in variety of applications such as surgery. These mechanisms are compared qualitatively and their applications as haptic devices are discussed.

In this paper, the desired configuration for installation of Delta robot is formulated as an optimization problem and has been solved to reach to the highest rate of pick and place operation. The optimization is performed considering the actuators speed and acceleration limitation of the robot within the workspace. Furthermore, energy consumption is considered next as the other optimization objective, and it is shown that the optimal region for the first optimization problem lies within that of the latter one, and therefore, there is no need to propose a multi-objective optimization problem in this case. As a proof of concept, KNTU Delta robot is designed and implemented in practice by using the optimal configuration, and it is observed that the optimal design is very promising in practice.

In this paper dynamic analysis and control of fully-constrained parallel cable robots are studied in detail. In dynamic analysis, it is assumed that the dominant dynamics of cable can be approximated by linear axial spring. Furthermore, variable stiffness formulation for the cables is employed in modeling process. To overcome vibrations caused by inevitable elasticity of cables, a composite control law is proposed based on singular perturbation theory. Using the proposed control algorithm the dynamics of the cable robot is divided into two subsystems namely slow and fast. Then, based on the results of singular perturbation theory, stability analysis of the total system is performed. Finally, the effectiveness of the proposed composite control law is investigated through several simulations on a planar parallel cable robot.

This paper presents a method for online trajectory planning of cable suspended robots. A three degrees-of-freedom spatial cable robot is studied in this analysis. By deriving dynamic model of the robot, cable force restrictions will induce a set of algebraic inequalities in dynamic equations. Direction of required tracking acceleration reveals feasible motion of the robot, which guarantees non-violation of cable force bilateral bounds. Required tracking acceleration is in the direction of instantaneous minus desired velocity vectors with specified magnitude. Furthermore, alternative recipes are employed to decrease negative impacts of unwanted inputs and applying actuator constraints in trajectory planning. Finally, several simulations are presented to demonstrate success of the method. Proposed approach can be used in online trajectory tracking for all cable-driven parallel suspended robots akin to what is realized for the presented three degrees-of-freedom robot.

Analytic Iterative Redundancy Resolution (AIRR) is a semi-analytic method for redundancy resolution in cable-driven manipulators. As all previous redundancy resolution methods were based on numerical algorithms, they impose an uncertainty to execution time which is barely acceptable in realtime implementation. In this paper, AIRR is implemented as a fast solution to redundancy resolution problem by checking a set of analytic solutions instead of using numerical algorithms. Furthermore, the performance of this method is compared to previous numerical method implemented on KNTU robot with respect to execution time and accuracy. It is shown that the realtime performance of this implementation in closed-loop control structure is at least fifteen times faster than that of previously implemented methods. Such decrease in execution time in realtime implementation is very promising for future applications.

In this paper dynamic analysis and robust PID control of fully-constrained cable driven parallel manipulators are studied in detail. Since in this class of manipulators cables should remain in tension for all maneuvers in their workspace, feedback control of such robots becomes more challenging than that of conventional parallel robots. In this paper, structured and unstructured uncertainties in dynamics of the robot are considered and a robust PID controller is proposed for the cable robot. To ensure that all cables remain in tension internal force concept is used in the proposed PID control algorithm. Then, robust stability of the closed-loop system with proposed control algorithm is analyzed through Lyapunov direct method and it is shown that by suitable selection of the PID controller gains, the closed-loop system would be robustly stable. Finally, the effectiveness of the proposed PID algorithm is examined through experiments on a planar cable driven robot and it is shown that the proposed control structure is able to provide suitable performance in practice.

In this paper, some new kinematic performance indices are proposed and examined on four planar cable driven parallel manipulators. The main kinematic indices are based on kinematic sensitivity and controllable workspace of the robot. Interval analysis is adopted as a mathematical framework to compute feasible kinematic sensitivity and worst kinematic sensitivity indices. For determining the feasible kinematic sensitivity, the controllable workspace is combined with the desired kinematic sensitivity property. The area of the foregoing region and the worst kinematic sensitivity corresponding to it are introduced as practical design indices. Then four typical design of planar cable robot are examined by the following performance measures, and one of such designs are selected and implemented in practice.

In this paper design and control of planar cable-driven parallel robots are studied in an experimental prospective. Since in this class of manipulators, cable tensionability conditions must be met, feedback control of such robots becomes more challenging than for conventional robots. To meet these conditions, internal force control structure is introduced and used in addition to a PID control scheme to ensure that all cables remain in tension. A robust PID controller is proposed for partial knowledge of the robot, to keep the tracking errors bounded. Finally, the effectiveness of the proposed control algorithm is examined through experiments on K.N. Toosi planar cable-driven robot and it is shown that the proposed control structure is able to provide suitable performance in practice.

The kinematic sensitivity has been recently proposed as a unit-consistent performance index to circumvent several shortcomings of some notorious indices such as dexterity. This paper presents a systematic interval approach for computing an index by which two important kinematic properties, namely feasible workspace and kinematic sensitivity, are blended into each other. The proposed index may be used to efficiently design different parallel mechanisms, and cable driven robots. By this measure, and for parallel manipulators, it is possible to visualize constant orientation workspace of the mechanism where the kinematic sensitivity is less than a desired value considered by the designer. For cable driven redundant robots, the controllable workspace is combined with the desired kinematic sensitivity property, to determine the so-called feasible kinematic sensitivity workspace of the robot. Three case studies are considered for the development of the idea and verification of the results, through which a conventional planar parallel manipulator, a redundant one and a cable driven robot is examined in detail. Finally, the paper provides some hints for the optimum design of the mechanisms under study by introducing the concept of minimum feasible kinematic sensitivity covering the whole workspace.

Particle lters are widely used in mobile robot localization and mapping. It is well-known that choosing an appropriate proposal distribution plays a crucial role in the success of particle lters. The proposal distribution conditioned on the most recent observation, known as the optimal proposal distribution (OPD), increases the number of eective particles and limits the degeneracy of lter. Conventionally, the OPD is approximated by a Gaussian distribution, which can lead to failure if the true distribution is highly non-Gaussian. In this paper we propose two novel solutions to the problem of feature-based SLAM, through Monte Carlo approximation of the OPD which show superior results in terms of mean squared error (MSE) and number of eective samples. The proposed methods are capable of describing non-Gaussian OPD and dealing with nonlinear models. Simulation and experimental results in large-scale environments show that the new algorithms outperform the aforementioned conventional methods.

The growing interest in the use of parallel manipulators in machining applications requires clear determination of the workspace and dexterity. In this paper, the workspace optimization of a Tricept parallel manipulator under joint constraints is performed. This parallel manipulator has complex degrees of freedom and, therefore, leads to dimensionally inhomogeneous Jacobian matrices. Here, we divide the Jacobian entries by units of length, thereby producing a new Jacobian that is dimensionally homogeneous. By multiplying the associated entries of the twist array to the same length, we made this array homogeneous as well. The workspace of the manipulator is parameterized using several design parameters and is optimized using a genetic algorithm. For the workspace of the manipulator, local conditioning indices and minimum singular values are calculated. For the optimal design, it is shown that by introducing the local conditioning indices and minimum singular values, the quality of the parallel manipulator is improved at the cost of workspace reduction.

In this paper modeling and control of cable driven redundant parallel manipulators with flexible cables, are studied in detail. Based on new results, in fully constrained cable robots, cables can be modeled as axial linear springs. Considering this assumption the system dynamics formulation is developed using Lagrange approach. Since in this class of robots, all the cables should remain in tension for the whole workspace, the notion of internal forces are introduced and incorporated in the proposed control algorithm. The control algorithm is developed in cable coordinates in which the internal forces play an important role. Finally, asymptotic stability of the closed loop system is analyzed through Lyapunov theorem, and the performance of the proposed algorithm is studied by simulations.

In this paper, dynamic analysis of cable-driven parallel manipulators (CDPMs) is performed using the Lagrangian variable mass formulation. This formulation is used to treat the effect of a mass stream entering into the system caused by elongation of the cables. In this way, a complete dynamic model of the system is derived, while preserving the compact and tractable closed-form dynamics formulation. First, a general formulation for a CDPM is given, and the effect of change of mass in the cables is integrated into its dynamics. The significance of such a treatment is that a complete analysis of the dynamics of the system is achieved, including vibrations, stability, and any robust control synthesis of the manipulator. The formulation obtained is applied to a typical planar CDPM. Through numerical simulations, the validity and integrity of the formulations are verified, and the significance of the variable mass treatment in the analysis is examined. For this example, it is shown that the effect of introducing a mass stream into the system is not negligible. Moreover, it is non linear and strongly dependent on the geometric and inertial parameters of the robot, as well as the maneuvering trajectory.

This paper deals with the optimization of 3-RPR planar parallel mechanisms based on different performance indices including the kinematic sensitivity, the workspace and the singularity locus. Since the kinematic sensitivity has been proposed only recently, more emphasis is placed on how it should be adapted for the optimization of 3-RPR parallel mechanisms. The optimization is implemented in sequence using first a single objective technique, differential evolution, and then resorting to a multi-objective optimization concept, the so-called Non-dominated sorting genetic algorithm-II. A Pareto-based multi-objective approach helps to overcome the problem of unit-inconsistent objectives in the optimization algorithm. Moreover, an Infinity-norm is used in computation of the kinematic sensitivity which has perhaps the clearest physical interpretation.

This paper presents a new approach to the modeling and control of cable driven parallel manipulators and particularly KNTU CDRPM. First, dynamical model of the cable driven parallel manipulator is derived considering the elasticity of the cables, and then this model is rewritten in the standard form of singular perturbation theory. This theory used here as an effective tool for modeling the cable driven manipulators. Next, the integrated controller, applied for control of the rigid model of KNTU CDRPM in previous researches, is improved and a composite controller is designed for the elastic model of the robot. Asymptotic stability analysis of the proposed rigid controller is studied in detail. Finally, a simulation study performed on the KNTU CDRPM verifies the closed-loop performance compared to the rigid model controller.

This paper investigates the constant-orientation workspace of five-degree-of-freedom parallel mechanisms generating the three translations and two independent rotations and comprising five identical limbs of the type. The general mechanism was proposed recently from the type synthesis performed for 5-DOF parallel mechanisms with identical limb structures. In this study, the emphasis is placed on the determination of the constant-orientation workspace using a geometric interpretation of the so-called vertex space, i.e., the motion generated by a limb for a given orientation. The geometric investigation is carried out using geometric constructive approach, which is implemented in a computer algebra system and in a CAD system. This paper shows that these two approaches are complementary tools to investigate the workspace of parallel mechanisms. The geometric constructive approach proposed in this paper bring insight into the architecture optimization and it can be regarded as a guideline for the workspace analysis of parallel mechanisms whose vertex spaces generate Bohemian dome.

In this paper, redundancy resolution of a cable-driven parallel manipulator is solved by an iterative-analytic scheme. The method can be applied to all kind of redundant manipulators either parallel or serial with constraint caused through their dynamics. However, for sake of simulation the proposed method is implemented on a cable-driven redundant parallel manipulator (CDRPM). The redundancy resolution problem is formulated as a convex optimization with equality and non-equality constraints caused by manipulator structure and cables dynamics. Karush-Kuhn-Tucker theorem is used to analyze the optimization problem and to find an analytic solution. Subsequently, a tractable and iterative search algorithm is proposed to solve the redundancy resolution of such redundant mechanisms. Furthermore, it is shown through the simulation that, the elapsed time required to implement the analytical redundancy resolution scheme in a closed-loop structure is considerably less than that of other numerical optimization methods.

This paper investigates some kinematic properties of a five-degree-of-freedom parallel mechanism generating the 3T2R motion and comprising five identical limbs of the RP?UR type. In this study, two classes of simplified designs are proposed whose forward kinematic problems have either a univariate or a closed-form solution. The principal contributions of this study are the solution of the forward kinematic problem for some simplified designs—which may have more solutions than the FKP of the general 6-DOF Stewart platform with 40 solutions—and the determination of the constant orientation workspace based on algebraic geometry (Bohemian domes).

Newly developed cable driven redundant parallel manipulators (CDRPM) have numerous advantages compared to that of the conventional parallel mechanisms. However, there exist some challenging issues in over-constrained mechanisms like CDRPMs. In contrast to serial manipulators, complexity of parallel manipulator forward kinematics (FK) is one of the main issues being under study in the control of such manipulators. Moreover, using extra sensory data is a common approach in the FK solution of rigid-linked parallel manipulators, which is considered by fewer researchers for CDRPMs. In this paper, tension force sensors of the cables are used as an extra sensor to simplify analytical solution of the FK for a planar CDRPM. To find a suitable solution, geometrical and physical characteristics of the robot are analyzed. It is shown that the proposed method provides the required accuracy and significantly improves the process time compared to the conventional methods.

This paper investigates some kinematic properties of a five-degree-of-freedom parallel mechanism generating the 3T2R motion and comprising five identical limbs of the RPUR type. The general mechanism originates from the type synthesis performed for symmetrical 5-DOF parallel mechanism. In this study, two classes of simplified designs are proposed whose forward kinematic problem have either a univariate or a closed-form solution. The principal contributions of this study are the solution of the forward kinematic problem for some simplified designs—which may have more solutions than the FKP of the general 6-DOF Stewart platform with 40 solutions—and the determination of the constant-orientation workspace which is based on the topology of the vertex space (Bohemian dome) and a geometric constructive approach.

KNTU CDRPM is a cable driven redundant parallel manipulator, which is under investigation for possible implementation in large workspace applications. This type newly developed manipulator has numerous advantages compared to that of the conventional parable mechanisms. The rotational motion range is relatively large, the inherent redundancy improves dexterity of the manipulator, and the light weight structure makes the robot more energy efficient and significantly fast. However, there exist some challenging issues in the over-constrained mechanism like KNTU CDRPM. Collision avoidance, force feasibility, and linear independency of the cables are the main issues being under study in the design of such manipulators. In this paper, singularity of the KNTU CDRPM is studied in detail. To extract kinematic properties of the robot, the inverse and forward kinematics are analyzed. It is shown that singularity analysis can well describe the characteristics of the design and provide the sufficient means to the designer to improve these characteristics. Finally, a suitable design strategy is proposed to significantly reduce the singularity of the manipulator within its whole workspace. The outcomes of this strategy implemented on KNTU CDRPM result in a significant improvement of the singular free workspace of the proposed design compared to that of the latest parallel manipulators.

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 paper the kinematic and Jacobian analysis of a macro–micro parallel manipulator is studied in detail. The manipulator architecture is a simplified planar version adopted from the structure of the Large Adaptive Reflector (LAR), the Canadian design of the next generation of giant radio telescopes. This structure is composed of two parallel and redundantly actuated manipulators at the macro and micro level, which both are cable-driven. Inverse and forward kinematic analysis of this structure is presented in this paper. Furthermore, the Jacobian matrices of the manipulator at the macro and micro level are derived, and a thorough singularity and sensitivity analysis of the system is presented. The kinematic and Jacobian analysis of the macro–micro structure is extremely important to optimally design the geometry and characteristics of the LAR structure. The optimal location of the base and moving platform attachment points in both macro and micro manipulators, singularity avoidance of the system in nominal and extreme maneuvers, and geometries that result in high dexterity measures in the design are among the few characteristics that can be further investigated from the results reported in this paper. Furthermore, the availability of the extra degrees of freedom in a macro–micro structure can result in higher dexterity provided that this redundancy is properly utilized. In this paper, this redundancy is used to generate an optimal trajectory for the macro–micro manipulator, in which the Jacobian matrices derived in this analysis are used in a quadratic programming approach to minimize performance indices like minimal micro manipulator motion or singularity avoidance criterion.

KNTU CDRPM is a cable driven redundant parallel manipulator, which is under investigation for possible implementation of large workspace applications. This newly developed manipulators have several advantages compared to the conventional parable mechanisms. In this paper, the governing dynamic equation of motion of such structure is derived using the Newton-Euler formulation. Next, the dynamic equations of the system are used in simulations. It is shown that on the contrary to serial manipulators, dynamic equations of motion of cable-driven parallel manipulators can be only represented implicitly, and only special integration routines can be used for their simulations. In order to verify the accuracy and integrity of the derived dynamic equations, open- and closed-loop simulations for the system is performed and analyzed. Also, the effects of mechanical assembly tolerances on the closed-loop control performance of a cable driven parallel robot are studied in detail, and the sensitivity analysis of the precision in the construction and assembly of the system on the closed-loop behavior of the KNTU CDRPM is performed.

KNTU CDRPM is a cable driven redundant parallel manipulator, which is under investigation for possible high speed and large workspace applications. This newly developed mechanisms have several advantages compared to the conventional parallel mechanisms. Its rotational motion range is relatively large, its redundancy improves safety for failure in cables, and its design is suitable for long-time high acceleration motions. In this paper, collision-free workspace of the manipulator is derived by applying fast geometrical intersection detection method, which can be used for any fully parallel manipulator. Implementation of the algorithm on the Neuron design of the KNTU CDRPM leads to significant results, which introduce a new style of design of a spatial cable-driven parallel manipulators. The results are elaborated in three presentations; constant-orientation workspace, total orientation workspace and orientation workspace.

This paper devises a multi-objective cost function which elaborates different constraints as well as an optimality criterion for design of serial robotic manipulators. In practice, inclusion of different constraints drastically limits the possible range of design parameters. The result of minimizing this multi-objective cost function is compared with another method which locates an optimal solution using a graphical representation. The effectiveness of the proposed cost function is demonstrated by a unified solution for both methods. In addition, possible tolerance of design parameters is compensated by considering a neighborhood around these parameters. Through an illustrative example, it is shown that the inclusiveness and flexibility of the proposed method makes it suitable for geometric design optimization of robotic manipulators.

In this paper,positioncontrol has been designed for a 3 DOF actuator redundant sphericnl parallel manipulator.A two norm minimization approach has been used to resolve the actuator redundancy problem. Robust stability of the closed loop system is analyzed considering uncertainties inherent in the dynamic model of the manipulator.A simulation study is also performed to showthe effectiveness of the proposed method. Thc results show the applicability of simple and conventional controllersto control redundant spherical parallel manip lators

In this paper, kinematic modeling and singularity and stiffness analysis of a 3-d.o.f. redundant parallel manipulator have been elaborated in detail. It is known that, contrary to series manipulators, the forward kinematic map of parallel manipulators involves highly coupled non-linear equations, whose closed-form solution derivation is a real challenge. This issue is of great importance noting that the forward kinematics solution is a key element in closed-loop position control of parallel manipulators. Using the idea of inherent kinematic chains formed in parallel manipulators, both inverse and forward kinematics of the redundant parallel manipulator are fully developed, and a closed-form solution for the forward kinematic map of the parallel manipulator is derived. The closed-form solution is also obtained in detail for the Jacobian of the mechanism and singularity analysis of the manipulator is performed based on the computed Jacobian. Finally, as the first step to develop a control topology based on the overall stiffness property of the manipulator, the stiffness mapping of the manipulator is derived and its configuration dependence is analyzed. It is observed that the actuator redundancy in the mechanism is the major element to improve the Cartesian stiffness and, hence, the dexterity of the hydraulic shoulder. Moreover, loosing one limb actuation reduces the stiffness of the manipulator significantly.

In this paper, a model-based impedance control strategy is developed for a 3 DOF parallel manipulator to manage the interaction of the robot with the environment. Kinematic and dynamic modeling of the manipulator has been analyzed in order to be used for both simulation and control purposes. The impedance controller objective and the structure of the proposed controller are introduced and controller gain selection is discussed. A simulation study evaluates the effectiveness of the proposed impedance control structure. It is observed that although the proposed controller is designed for impedance adjustment of the robot, in case of free motion, it results into desirable position tracking. Moreover, when the robot comes into contact with the environment, the interaction dynamics can be regulated regardless of the nonlinear dynamics of the robot.

In this paper, kinematic modeling of a three DOF redundant parallel manipulator has been elaborated in detail. It is known, that on the contrary to series manipulators, the forward kinematic map of parallel manipulators involves highly coupled nonlinear equations, whose closed-form solution derivation is a real challenge. This issue is of great importance noting that the forward kinematics solution is a key element in closed loop position control of parallel manipulators. Using the novel idea of kinematic chains recently developed for parallel manipulators, both inverse and forward kinematics of our parallel manipulator are fully developed, and a closed-form solution for the forward kinematic map of the parallel manipulator is derived. The closed form solution is finally verified by simulated trajectories in the workspace of the manipulator.

In this paper, three numerical methods are presented to solve the forward kinematics of a three DOF actuator-redundant hydraulic parallel manipulator. It is known, that on the contrary to series manipulators, the forward kinematic map of parallel manipulators involves highly coupled nonlinear equations, whose closed-form solution derivation is a real challenge. This issue is of great importance noting that the forward kinematics solution is a key element in closed loop position control of parallel manipulators. The proposed methods, namely the Neural Network Estimation, the Quasi-closed Solution, and the Taylor series approximation, are using mainly numerical computations, with different ideas to solve the problem in hand. The latter two methods are proposed for the first time in literature to solve the forward kinematics of a parallel manipulator. These methods are compared in detail and the advantages or the disadvantages of each method in computing the forward kinematic map of the given mechanism is discussed. It is shown that a 4th order Taylor series approximation to the problem provides a good compromise for practical applications compared to that of other methods considered in this paper.

In this paper a new and completely linear algorithm is proposed for composite robust control of flexible joint robots. Moreover, the robust stability of the closed loop system in the presence of structured and unstructured uncertainties is analyzed. To introduce the idea, flexible joint robot with structured and unstructured uncertainties is modelled and converted into singular perturbation form. A robust linear control algorithm is proposed for the slow dynamics and its robust stability conditions are derived using Thikhonov's theorem. Then the robust stability of the total system considering the proposed composite controller is analyzed, and sufficient conditions for robust stability of system is obtained. Finally the effectiveness of the proposed controller is verified through simulations. It is shown that not only the tracking performance of the proposed controller is very suitable, but also the actuator effort is much smaller than previous result.