In this paper, a new type of large-dimension reconfigurable suspended cable-driven parallel robots (CDPR) is introduced as a means to substitute for conventional methods of handing large and heavy parts across wide workspaces. The reconfigurability of the proposed CDPR offers better performances in term of workspace, flexibility and power consumption. A systematic procedure to solve a complex nonlinear optimization problem to find optimal reconfiguration for the robot is presented. Critical issues regarding various constraints and performance criteria are addressed. The robot can operate in offline reconfiguration or online reconfiguration modes which offer wide range of solutions to the end-users.

The paper presents a novel 5 dofs (3T-2R) parallel mechanism. The mechanism is characterized by large singularity-free workspace and particularly large rotational capability which makes it suitable for 5 face-machining and similar applications. Having all its prismatic actuators along x direction, the x-motion is independent from other dofs-only limited by prismatic actuators' strokes-constituting another major advantageous feature. Besides, an analytical direct geometric model can be easily established which is a rare feature in parallel robots. The paper introduces the novel mechanism with its inverse and direct geometric models as well as its kinematic models (forward and inverse Jacobians). Also, it discusses its singularity analysis and presents sample workspace plots evaluated based on isotropic performance regarding velocity and static force.

This paper deals with the kinetostatic performance evaluation regarding translational and rotational motions of general robots with mixed operational degrees of freedom (dofs). Also, robots with different types of actuators can be analyzed based on the same approach without any problem. Besides, the generality of the approach embraces serial, parallel, actuatedly or kinematically redundant robots. The paper seeks clarifying the issue and providing a relevant solution. It also clarifies some other useful points in this matter.

This paper presents the dimensional synthesis of a 4 dofs (3T-1R) actuatedly redundant parallel manipulator (called ARROW V1) based on dual criteria related to rapidity and precision. The dynamical (rapidity) criterion is the worst isotropic linear acceleration starting from rest, and the precision related criterion is the worst translational resolution amplification factor. This latter amplification factor happens to be equal to the theoretical translational repeatability and accuracy amplification factors as well. Also, other kinetostatic and dynamic performances have been evaluated for the synthesized set of geometric parameters as to validate global performances. The results are quite interesting showing a highly performant parallel kinematic machine (PKM).

This paper addresses the simplification of cable model in static analysis of large-dimension cable-driven parallel robots (CDPR). An approach to derive a simplified hefty cable model is presented. The approach provides an insight into the limitation of such a simplification. The resulting cable tension computation is then used to solve the inverse kinematic problem of CDPR. A new expression of cable length taking into account both the non-negligible cable mass and elasticity is also introduced. Finally, simulations and experiments on a large CDPR prototype are provided. The results show that taking into account both cable mass and elasticity improves the robot accuracy.

This paper presents a novel 4 dofs (3T-1R(1)) parallel redundant mechanism, with its complete study regarding inverse and direct geometric models (IGM and DGM), as well as singularity and workspace analysis. The robot is capable of performing a half-turn about the z axis (a complete turn would be theoretically possible if it were not for possible unavoidable inter-collisions in the practical case), and having all of its prismatic actuators along one direction, enables it to have an independent x motion - only limited by the stroke of the prismatic actuators. The mechanism is characterized by elevated dynamical capabilities having its actuators at base. Moreover, the performance of the robot is evaluated considering isotropy in velocity and forces.

This paper analyzes the possible contribution of actuation redundancy in obtaining very high acceleration with Parallel Kinematic Machines (PKM). This study is based on redundant and non-redundant Delta/Par4-like robots (frequently used for pick-and-place applications). The dynamic model, valid for both redundant and non-redundant robots, is used to analyze the traveling plate acceleration capabilities: (i) at zero speed and in any directions, (ii) at zero speed in the “best” direction. The results show that actuation redundancy allows to homogenize the dynamic capabilities throughout the workspace and to increase the traveling plate acceleration capability. Finally, the design of a redundant Delta/Par4-like robot optimized for typical pick-and-place trajectories is presented.

This paper deals with the problem of unavailability of velocity measurements for the control of parallel manipulators for pick-and-place applications. As most controllers require the measurement of the joint positions as well as joint velocities, the latter need to be estimated. Three observers have been implemented while keeping the same nonlinear controller: a Lead-lag filter based observer, an Alpha-beta-gamma observer and a High-gain observer. The resulting performances obtained in Real-time experiments by each observer have been detailed and compared.

This paper introduces the Quadriglide, a Schonflies motion generator module for 5-axis machine-tools. The targeted application is high speed milling of long aeronautic parts, in particular thin ones, instead of toxic and dangerous chemical milling. Quadriglide is described and its kinematics derived. Then, a preliminary optimization is done to achieve the best actuation stiffness in a prescribed workspace with large tilting angles (thetas = plusmnpi/4). Workspace plots of the optimized module are shown at the end of the paper.

This paper introduces a new two-degree-of-freedom parallel manipulator producing two translations in the vertical plane. One drawback of existing robots built to realize those dof is their lack of rigidity along the transversal axis, another one being their limited ability to provide very high acceleration. Indeed, these architectures cannot be lightweight and stiff at the same time. The proposed architecture is a spatial mechanism which guarantees a good stiffness along the transversal axis. This parallel architecture is composed by two actuated kinematic chains, and two passive chains built in the transversal plane. The key feature of this robot comes from the passive chains which are coupled for creating a kinematic constraint: the platform stays in one plane. A stiffness analysis shows that the robot can be lighter and stiffer than a classical 2 dof mechanism. A prototype of this robot is presented and preliminary tests show that accelerations above 40 g can be achieved while keeping a low tracking error.

This paper deals with nonlinear dual mode adaptive control of a redundant manipulator for a pick-and-place scenario with high acceleration (20 G). For performance comparisons, a conventional Proportional-Derivative (PD) controller has also been implemented. In this context, the experimental testbed is not equipped with velocity sensors. Therefore, a high-gain observer has been implemented to estimate the articular velocities. Real-time experiments show the performance improvements obtained by the proposed control approach in comparison to the conventional one.

This paper presents an optimal design of a parallel manipulator aiming to perform pick-and-place operations at high speed and high acceleration. After reviewing existing architectures of high-speed and high-acceleration parallel manipulators, a new design of a 4-DOF parallel manipulator is presented, with an articulated traveling plate, which is free of internal singularities and is able to achieve high performances. The kinematic and simplified, but realistic, dynamic models are derived and validated on a manipulator prototype. Experimental tests show that this design is able to perform beyond the high targets, i.e., it reaches a speed of 5.5 m/s and an acceleration of 165 m/s2. The experimental prototype was further optimized on the basis of kinematic and dynamic criteria. Once the motors, gear ratio, and several link lengths are determined, a modified design of the articulated traveling plate is proposed in order to reach a better dynamic equilibrium among the four legs of the manipulator. The obtained design is the basis of a commercial product offering the shortest cycle times among all robots available in today's market.

This paper presents the design and the optimization of a parallel machine-tool composed of (i) an 3-dof actuated parallel mechanism (a linear Delta) and (ii) a 6-dof measuring parallel mechanism (a Gough platform).The measuring mechanism is used to control the actuated mechanism. The interest to use a measuring device independent of the actuation device is shown and the modeling of both devices used for the optimization is explained. Then, the optimization of both mechanisms is presented. The optimization of the actuated mechanism is performed to have an homogeneous behavior in velocity while the goal of the measuring device optimization is to obtain the best resolution for the measuring system evaluated at the tool level.

This paper presents the performance of a needle insertion teleoperated system with haptic feedback. Through a haptic device, the surgeon tele-operates the surgical needle, fixed on the remote robot that may evolve in free space or in contact. In free space, the surgeon feels the motion of the robot. During the needle insertion, the puncture of the tissue involves an abrupt and large change in the magnitude of the applied force. To perform and improve the tele-operated task, an on-line transparency improvement is achieved using the environment stiffness estimation. The transparency is improved based on the stability of the haptic feedback teleoperation scheme in which we distinguish between the voluntary and involuntary operator position. The quality of telepresence allows the surgeon to perform and exactly characterize the needle insertion phases without using additional transition detection techniques. To assess the proposed teleoperation scheme, a surgical needle rigidly attached to the robot and ex-vivo tissues are used.

This paper discusses the design of a control system for robotic-assisted surgery with haptic feedback. The operational space control has a position-position teleopearation architecture with the phantom in the loop, enabling telepresence in free-space and contact. The null space control guarantees that surgical kinematic constraints are fulfilled. Both task and posture control run active observers (AOBs) in Cartesian domain, taking into account force, velocity and position signals. Experiments with a D2M2 (direct drive medical manipulator) robot are presented

This paper introduces Heli4 a new 4 degree-of-freedom parallel robot. It is inspired by the Delta architecture, but was designed to overcome its limitations, using an articulated traveling plate. Unlike most articulated traveling plates, Heli4's traveling plate is very compact. Among other positive aspects is its symmetrical design. This paper gives the geometrical models, and particularly the forward position relationship which can be obtained in a closed form. In a third part, a detailed study of the robot singularities is made by taking into account the not-so-classic internal singularities.

This paper introduces the dynamic modeling and the identification of Par4, a four-degree-of-freedom parallel manipulator producing Schonflies motions (three translations and one rotation about a fixed axis). First of all, this paper presents how this robot is developed with the goal of reaching very high speed. Indeed, it is an evolution of Delta, H4 and I4 robots architectures: it keeps their advantages while overcoming their drawbacks. Experimentations done with the prototype prove that the robot is able to reach very high accelerations (15 G) and to perform an adept cycle in 0.25 s. In order to improve its dynamic accuracy, a dynamic control could be necessary. Thus, this paper presents the dynamic modeling of the manipulator using a simplified Newton-Euler approach. The originality of this computation is to model the traveling as two separated parts and to determine the dynamic effects applied on each of them. Finally, since a dynamic control requires a good evaluation of dynamic parameters, an experimental dynamic identification is presented

This paper deals with a particular family of lower mobility parallel kinematic manipulators. The four degrees of freedom of the end-effector consist of three translations plus one rotation with a high tilting angle. Robots belonging to this family are first introduced, and a common parameterization is established. Then an extended kinematic model is proposed for this family of robots using a new Jacobian matrix. Relevant information about robot kinematic singularities, internal singularities, and possible end-effector motions can be obtained by resorting to this matrix. The efficiency of this method is proven by applying it to several traveling-plate architectures corresponding to already built robot prototypes. The results of the expected behavior are compared with the prototype's real behavior. The goal of this paper is to show that internal (or constraint) singularities can occur in lower mobility parallel kinematic manipulators, and to underline the influence they have during the design stage.

The H4 robot is a four-degree of freedom (dof) parallel machine. The purpose of this work is to evaluate the H4 stiffness, ie the displacement response of the tool controlled point when it is submitted to a given force using an analytical method. A stiffness analysis based on analytical calculations is performed. It has the advantage to be rather fast and easy to integrate into a design optimization. This method allows to compute stiffness matrix of parallel robots and takes into account particularity of parallel robots with articulated traveling plate. Some numerical results are presented at the end of this paper for the H4 first prototype.

Nowadays an important research effort is devoted to lower mobility parallel manipulators. The existing solutions often suffer from parallel mechanisms drawbacks, i.e. small workspace and limited rotation capability. A new concept of parallel manipulators providing Schoen flies motions (motions of well-known SCARA robot) is introduced in this paper. The proposed manipulator, based on the idea of articulated traveling plate explored by the authors, has an unlimited rotation capability without using motion transformation, ampli fication neither redundancy.

This paper introduces a four-degree-of-freedom parallel manipulator dedicated to pick-and-place. It has been developed with the goal of reaching very high speed. This paper shows that its architecture is particularly well adapted to high dynamics. Indeed, it is an evolution of Delta, H4 and 14 robots architectures: it keeps the advantages of these existing robots, while overcoming their drawbacks. In addition, an optimization method based on velocity using adept motion has been developed and applied to this high speed parallel robot. All these considerations led to experimentations that proved we can reach high accelerations (13 G) and obtain a cycle time of 0.28 s.

The increasing level of requirements in terms of performance, accuracy, repeatability and resolution in the semiconductors industry leads to several technological problems; among them the positioning accuracy and resolution are peculiarly important. In this paper, we address the crucial issue of high resolution and fast positioning mechanisms. We propose a novel type of high resolution and fast positioning mechanism, based on a macro/micro architecture composed of two stages. We focus here on the micro-stage. It is a combination of: a 3-RRR planar parallel structure (3-RRR stands for 3 kinematic chains in parallel, each chain composed of 3 revolute joints R in a serial arrangement) with deported PRR actuation (a rod connected with two revolute joints R to a linear actuator P and to the RRR chain). This architecture provides stiffness, symmetry and interesting thermal properties; Flexible R links (which avoid the drawbacks of conventional links in terms of backlash, friction, wear, stick-slip,...); and near serial-singular configuration which results in an improvement of the resolution. A modeling of inverse kinematics for position and velocity is presented. Then, an optimization is run to find the best set of geometrical parameters for the micro-stage. An articulated kinematic scheme is finally presented.

This paper introduces a new 4 degree-of-freedom parallel robot. It presents its architecture inspired by FlexPicker, an ABB machine based on the Delta architecture, while overcoming its drawbacks. This paper exposes the way to get the geometrical models, and particularly the forward position relationship which can be obtained in a closed form. In a third part, a detailed study of the robot singularities is made by taking into account the not-so-classic internal singularities. Design conditions are obtained for isostatic and over-constrained cases. The robot optimization and its workspace are finally presented.

This paper presents new force performance indexes adapted to parallel mechanisms with actuation redundancy (PMAR) especially parallel wire-driven manipulators (where only tensile forces in cables are possible). Such performance indexes might be used for optimization purpose. At first, the operational force polytope is established. It is the accurate representation of admissible operational forces from the kinetostatic analysis point of view. A way to efficiently compute it is given. The obtained description of the polytope is the same as in (Krut S. et al., March-April 2004), but regarding forces. As a consequence the reader is free to use any of the indexes introduced in (Krut S. et al., March-April 2004). From the authors' point of view the "maximum operational isotropic force" is well adapted to characterize parallel wire-driven manipulators' force behavior. The way to compute it is established. At last, this index is computed for several parallel wire-driven manipulators.

This paper deals with the design and dynamic control simulation of a new type and dynamic control simulation of a new type of 4-DOFs parallel mechanism providing 3 translations and 1 rotation for high-speed handling and machining. This parallel mechanism is named as H4. A model-based dynamic control scheme is developed to improve the accuracy of the trajectory tracking. A simplified dynamic model is used for the H4 robot to decrease the cost of computation. A dynamic simulation is performed using ADAMS/sup TM/. In addition, the adept motion is used as a benchmark test to evaluate the effect of the dynamic control. The simulation results show that the dynamic control dramatically improves the trajectory tracking accuracy.

This paper presents a new robot which produces four motions for high speed handling (three translations and one rotation about a given axis in world coordinates). This machine is an evolution of H4's architecture. First, H4's advantages are recalled, and some limitations are mentioned. To compensate for these limitations a new design of the traveling plate is proposed. A description of the whole mechanism is given. The structure's ability to provide Scara motions is presented. Geometrical conditions that must be followed in order to obtain desired motions are discussed. Kinematics models are derived. The design of the first prototype is described.

This paper introduces Eureka, a new parallel mechanism providing five motions: three translations plus two rotations. This device is able to reach high tilting angles (/spl plusmn/90/spl deg/ about a first given axis and a whole revolution about the following axis). This is due to actuation redundancy and to the specific traveling plate. Kinematic models are derived. Due to its particular shape the forward geometrical model is also derived easily. A plot of its well conditioned workspace is given. Practical designs, free of self-collisions, are shown.

The forward kinematic model (FKM) of a redundantly actuated robot is not unique: if each actuator is equipped with an encoder, there are more joint data than strictly necessary for computing nacelle position. It is then possible to fuse competitive data to find the nacelle position. This paper proposes then a method based on a probabilistic approach to determine how computing the FKM to obtain, in terms of probability, the lowest Cartesian error.

This paper presents a new family of fully-parallel robots producing motions of the Schoenflies displacements subgroup (three translations and one rotation about a given axis in world coordinates) for high-speed handling and machining. First, the structure's ability to provide this four-degrees-of-freedom motion is presented. Then, two of its possible designs are analyzed: the symmetrical and the asymmetrical one. Constructive designs are then presented. Some of the prototype's preliminary control results are given to prove the H4 robot's efficiency.

Twice (tilling device with wide capacity), a new amplification device able to double the tilting angle of a parallel mechanism, is presented. A singularity analysis is carried out: it proves that Twice can give a huge tilting angle to parallel kinematic machines. Finally, practical implementation features are discussed.

This paper introduces a control strategy based on redundant sensors that leads to parallel robots accuracy enhancement. The method is presented in general, then applied to a 4-DOF parallel robot. Practical implementation issues, simulation results and experimental validation are addressed.

This paper first recalls the concept of H4 parallel mechanism, and the kinematic models necessary for real-time control are derived. A simple and efficient control system based on a combination of Windows NT and RTX is used to demonstrate its performances. Results prove the efficiency of H4 serving as a high-speed pick-and-place robot.

Presents a 3-DOF redundant parallel mechanism, ARCHI, designed as a sub-part of a 5-axis hybrid machine. The redundant parallel mechanism design and its models are recalled; different ways for its control and first motion results are presented, proving the ability of ARCHI to offer an unlimited rotation capability.