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Showing papers on "Revolute joint published in 1988"


Journal ArticleDOI
TL;DR: In this paper, a planar polysilicon mechanism incorporating lower and higher kinematic pairs (or joints) was described, which is compatible with silicon microfabrication technology.
Abstract: The integrated fabrication of planar polysilicon mechanisms incorporating lower and higher kinematic pairs (or joints) is described. The two lower kinematic pairs (revolute and prismatic) commonly used in macrorobotic systems are compatible with silicon microfabrication technology. The mechanisms are fabricated by surface micromachining techniques using polysilicon as the structural material and oxide as the sacrificial material. Turbines with gear and blade rotors as small as 125 mu m in diameter and 4.5 mu m in thickness were fabricated on 20- mu m-diameter shafts. A clearance as tight as 1.2 mu m was achieved between the gear and the shaft. Gear trains with two or three sequentially-aligned gears were successfully meshed. A submillimeter pair of tongs with 400- mu m range-of-motion at the jaws was fabricated. This structure incorporates a single prismatic joint and two revolute joints, demonstrating linear-to-rotary motion conversion. >

213 citations


Journal ArticleDOI
F. Behi1
01 Oct 1988
TL;DR: A Stewart-platform-based six-degree-of-freedom parallel mechanism is presented that can be used as a general-purpose spatial manipulator arm and uses screw theory to identify the geometric singularities of the manipulator in order to avoid undesirable robot configurations.
Abstract: A Stewart-platform-based six-degree-of-freedom parallel mechanism is presented that can be used as a general-purpose spatial manipulator arm. The system consists of an output platform which is connected to a fixed base by means of three PRPS (parameters P, R, and S denote the prismatic, revolute, and spherical joints) subchains. All prismatic joints in this mechanism are active inputs which control the platform's motion. The author provides a detailed investigation describing the mechanism and analyzing its forward and reverse position functions. A closed-form solution is presented to obtain the required inputs for a desired position and orientation of the output platform. A forward position analysis of this mechanism is formulated which can be solved numerically to determine the platform's position and orientation for a set of given inputs. The author examines the workspace and uses screw theory to identify the geometric singularities of the manipulator in order to avoid undesirable robot configurations. >

150 citations


Journal ArticleDOI
TL;DR: It was shown that SOC had a performance slightly superior to that of a PID controller when noise was present and the process had time varying coefficients as well as pronounced non-linear characteristics.

121 citations


Journal ArticleDOI
TL;DR: A fundamental theorem for the kinematic design of robot manipulators is formulated and proved that a manipulator having six revolute joints is optimal if and only if the manipulator or its kine matic inverse is an elbow manipulator.
Abstract: A fundamental theorem for the kinematic design of robot manipulators is formulated and proved. Roughly speaking, the theorem states that a manipulator having six revolute joints is optimal if and only if the manipulator or its kine matic inverse is an elbow manipulator. By "optimal" we mean a manipulator that has the properties of (i) maximal work-volume subject to a constraint on its length and (ii) well-connected workspace—that is, the ability to reach all positions in its workspace in each configuration. The notion of work-volume we use is that derived from the translation- invariant volume form on the group of rigid motions. This notion of volume is intermediate between those of "reach able" and "dextrous" workspace and appears to be more natural in that it leads to simple analytical results.

101 citations


Journal ArticleDOI
01 Apr 1988
TL;DR: A minimum time trajectory planner is proposed for a manipulator arm and it is numerically verified that the convergence of the iterative algorithm is quadratic, and the trajectory planner therefore is computationally efficient.
Abstract: A minimum time trajectory planner is proposed for a manipulator arm. A totally discrete approach is adopted, in contrast to other models which use continuous-time but resort to discretization in the computation. The Neuman and Tourassis discrete-dynamic robot model is used to model the robot dynamics. The proposed trajectory planner includes joint-torque constraints to fully utilize the joint actuators. Realistic constraints such as the joint-jerk and joint-velocity constraints are incorporated into the model. The nonlinear optimization problem associated with the planner is partially linearized, which enables the iterative method of approximate programming to be used in solving the problem. Numerical examples for a two-link revolute arm are presented to demonstrate the use of the proposed trajectory planner. It is numerically verified that the convergence of the iterative algorithm is quadratic, and the trajectory planner therefore is computationally efficient. The use of a near-minimum time-cost function is also shown to yield a solution close to that obtained with the true minimum time-cost function. >

63 citations


Journal ArticleDOI
01 Dec 1988
TL;DR: The authors use orthogonal second-order Cartesian tensors to formulate the Newton-Euler dynamic equations for a robot manipulator and develop two efficient recursive algorithms for computing the joint actuator torques/forces.
Abstract: The authors use orthogonal second-order Cartesian tensors to formulate the Newton-Euler dynamic equations for a robot manipulator. Based on this formulation, they develop two efficient recursive algorithms for computing the joint actuator torques/forces. The proposed algorithms are applicable to all rigid-link manipulators with open-chain kinematic structures with revolute and/or prismatic joints. An efficient implementation of one of the proposed algorithms shows that the joint torques/forces for a six-degrees-of-freedom manipulator with revolute joints, can be computed in approximately 489 multiplications and 420 additions. For manipulators with zero or 90 degrees twist angles, the required computations are reduced to 388 multiplications and 370 additions. For manipulators with even simpler geometric structures, these arithmetic operations can be further reduced to 277 multiplications and 255 additions. >

39 citations


Journal ArticleDOI
01 May 1988
TL;DR: An efficient method that finds collision-free paths for a manipulator with six revolute joints is described, and a global structure of the free space in the three-dimensional (3-D) joint space of the arm of a large open space inThe workspace is represented.
Abstract: An efficient method that finds collision-free paths for a manipulator with six revolute joints is described. A global structure of the free space in the three-dimensional (3-D) joint space of the arm of a large open space in the workspace, defined as a space where any orientation of the hand is possible, is represented in this description. >

37 citations


Proceedings ArticleDOI
24 Apr 1988
TL;DR: A hybrid position/force control algorithm was implemented on a PUMA 600 series robot and several programs were written to show various force and position tracking abilities.
Abstract: A hybrid position/force control algorithm was implemented on a PUMA 600 series robot. Multiple processors were used to increase the sampling frequency of the control algorithm. The force control algorithm used the hand Jacobian and hand frame force measurement fingers mounted in a gripper to control the forces and moments applied by the end effector. The position control algorithm used the Lagrange-Euler formulation of the dynamics of the arm to control the joint space trajectory of the arm. The algorithms' performance was evaluated using a proportional controller for the force control half and a proportional-derivative controller for the position control half. Several programs were written to show various force and position tracking abilities. >

29 citations


Proceedings ArticleDOI
24 Apr 1988
TL;DR: The optimal trajectory planning problem for planar n-link (n=2,3) revolute manipulators in the presence of obstacles is considered and closed-form approximations of obstacles in terms of the generalized coordinates of the manipulator are obtained.
Abstract: The optimal trajectory planning problem for planar n-link (n=2,3) revolute manipulators in the presence of obstacles is considered. A method for modeling the obstacles is proposed. Through the proposed method, closed-form approximations of obstacles in terms of the generalized coordinates of the manipulator are obtained. These expressions are then used to formulate the optimal trajectory planning problem as an optimal control problem in constrained state space. The resulting optimal control problem is then solved numerically. >

27 citations


Proceedings ArticleDOI
24 Apr 1988
TL;DR: An algorithm by which the inverse kinematics of a robot manipulator with closed-form solution can be computed in parallel to reduce the computational complexity roughly by a factor of n, the number of joints of the manipulator is introduced.
Abstract: Introduces an algorithm by which the inverse kinematics of a robot manipulator with closed-form solution can be computed in parallel to reduce the computational complexity roughly by a factor of n, the number of joints of the manipulator. The authors study the errors introduced by the algorithm by constructing statistical models of the errors. They evaluate the algorithm on a PUMA 260 manipulator, which has six degrees of freedom with six revolute joints and a reach of approximately 0.5 m. >

24 citations


Proceedings ArticleDOI
07 Dec 1988
TL;DR: The results indicate that proper positioning of the task in the workspace can considerably reduce the cycle time and therefore increase productivity.
Abstract: A novel approach to optimal placement of a prescribed task in the workspace of a robotic manipulator is presented. The cycle time for a specified set of minimum-time straight-line movements is used as the optimality criterion. These movements are point-to-point, and the arm starts from standstill at the initial point and stops at the final point. Local velocity patterns for minimum-time straight-line movements in the regions of interest are obtained. This information is used to choose a good initial location for the task. A step-and-test method is then used to find the minimum-cycle-time location for the considered task. Results of application of this method to a manipulator with two revolute joints are presented. The results indicate that proper positioning of the task in the workspace can considerably reduce the cycle time and therefore increase productivity. >

Journal ArticleDOI
TL;DR: In this article, a modele mathematique d'un robot avec des articulations prismatiques and des articulation de revolution en tenant compte des deformations elastiques.

Journal ArticleDOI
TL;DR: In this paper, the synthesis equations of RPCPRR spatial motion generators with revolute, prismatic and cylindric pairs are described. And the conditions for avoidance of branching are developed in Ref.

Proceedings ArticleDOI
24 Apr 1988
TL;DR: An efficient implementation of the proposed method shows that the joint torques for a six-degree-of-freedom manipulator with revolute joint, can be computed in approximately 500 multiplications and 420 additions.
Abstract: Orthogonal second-order Cartesian tensors are used to formulated the Newton-Euler dynamic equations for a robot manipulator. Based on this formulation, an efficient recursive procedure is developed to evaluate the joint torques. The procedure is applicable to all rigid-link manipulators with open-chain kinematic structures with revolute and/or prismatic joints. For simplicity of presentation, only manipulators with (kinematically more complex) revolute joints are considered. An efficient implementation of the proposed method shows that the joint torques for a six-degree-of-freedom manipulator with revolute joint, can be computed in approximately 500 multiplications and 420 additions. For manipulators with 0 degrees or 90 degrees twist angles, the required computations are reduced to 380 multiplications and 315 additions. >

Book ChapterDOI
26 May 1988
TL;DR: A simple and efficient algorithm for generating a approximate representation of the free Configuration Space for a robot moving in a workspace with obstacles is presented and can deal with all robots made of revolute or prismatic joints.
Abstract: This paper addresses the motion planning problem. We present a simple and efficient algorithm for generating a approximate representation of the free Configuration Space for a robot moving in a workspace with obstacles. The algorithms presented in this paper have been implemented and can deal with all robots made of revolute or prismatic joints. We present an exemple of collision-free trajectories computed by the system for a manipulator with 4 degrees of freedom.

Proceedings ArticleDOI
07 Dec 1988
TL;DR: In this article, the asymptotic properties of closed-loop trajectories of the rigid-body model of a controlled spacecraft with two independent pairs of gas jets are analyzed.
Abstract: The authors give an analysis and simulation of the asymptotic properties of various closed-loop trajectories of the rigid-body model of a controlled spacecraft. Recent results are described which show that the rigid body for a spacecraft controlled by two independent pairs of gas jets is locally controllable but not locally asymptotically stabilizable about reference attitudes. The authors analyze, in the context of feedback stabilization about an attractor, the asymptotic properties of closed-loop trajectories when a feedback law driving the motion to a revolute cycle about a principle axis is implemented. Simulations support such convergence but indicate that convergence is quite slow, due to the fact that this cycle lies, as it must, on an invariant center manifold for this system. In particular, while the design is based on a nonlinear enhancement of root-locus theory, such attractors have no linear analogue. >

Proceedings ArticleDOI
15 Jun 1988
TL;DR: In this paper, a new class of joint level control laws for all-revolute robot arms is introduced, and a sliding-mode-like modification of the control law is proposed to add a robustness enhancing outer loop.
Abstract: A new class of joint level control laws for all-revolute robot arms is introduced in this paper. The analysis is similar to the recently proposed energy Lyapunov function approach [1, 2], except that the closed loop potential function is shaped in accordance with the underlying joint space topology. By using energy Lyapunov functions with the modified potential energy, a much simpler analysis can be employed to show closed loop global asymptotic stability and local exponential stability. When Coulomb and viscous friction, and model parameter errors are present, a sliding-mode-like modification of the control law is proposed to add a robustness enhancing outer loop. Adaptive control is also addressed within the same framework. A linear-in-the-parameters formulation is adopted and globally asymptotically stable adaptive control laws are derived by replacing the model parameters in the non-adaptive control laws by their estimates.

13 Apr 1988
TL;DR: In this article, a nonlinear observer for robots with elastic joints is proposed, which estimates the whole state vector of a manipulator by using only the measurements of the joint global displacements and their time rates.
Abstract: Presents a procedure to design nonlinear observers for robots with elastic joints. This observer estimates the whole state vector of a manipulator by using only the measurements of the joint global displacements and their time rates. With reference to a particular two revolute joint robot some simulation tests to verify the goodness of the observer are reported. >

Journal ArticleDOI
TL;DR: In this paper, a nonlinear observer for robots with elastic joints is presented, which allows to reconstruct the whole state vector on the basis of the measurement of the joint global positions only.

Proceedings ArticleDOI
24 Apr 1988
TL;DR: An algorithm for interpolating workspace trajectories in the jointspace of a manipulator having revolute joints is described and it is shown that a particular induced pseudonorm of the Jacobian is bounded by the length of the manipulator and that a similar result holds for all derivatives of the forward kinematic map.
Abstract: An algorithm for interpolating workspace trajectories in the jointspace of a manipulator having revolute joints is described. The algorithm generates an interpolation so that a user-specified tolerance is maintained. In the process of developing this algorithm, it is shown that a particular induced pseudonorm of the Jacobian is bounded by the length of the manipulator and that a similar result holds for all derivatives of the forward kinematic map. The bounds obtained are used in the error analysis of the interpolation algorithm. >

Patent
02 Apr 1988
TL;DR: In this article, a condition is established such that a rotation stop control is applied to revolute joints N1-N4 to which no rotation command is given, and the position information about the tip T of an arm member and the target position information for location are acquired, and distance information between the tip position and target position A1 is determined, and any arbitrary direction is decided as the rotating direction of revolute joint.
Abstract: PURPOSE: To locate the tip of an arm member at the target position certainly and quickly by rotating each revolute joint a certain angle from the tip one by one in accordance with the size of the distance information value between the tip position of the arm member and the target position. CONSTITUTION: A condition is established such that a rotation stop control is applied to revolute joints N1-N4 to which no rotation command is given. Meantime the position information about the tip T of an arm member and the target position information for location are acquired, and the distance information between the tip position and target position A1 is determined, and any arbitrary direction is decided as the rotating direction of revolute joint. To this rotating direction decided, the revolute joint is rotated the specified angle. In case the distance information value is enlarged, the rotating direction is inverted to execute the rotational operation, and in case the distance information value has become small, the rotational operation is executed so that the distance information lessens. This rotational operation is repeated one after another from the revolute joint N4 located at the foremost, and the tip T of the arm member is located in the target position A1.

Proceedings ArticleDOI
08 Aug 1988
TL;DR: Any point along a planned Cartesian trajectory can be determined whether it is inside the robot's workspace, if it is in the region of singularity, and be provided with the suitable robot configurations.
Abstract: Due to the physical constraints of a robot manipulator, the successfulness of robot executing a planned Cartesian trajectory depends on the feasibility of this planned trajectory. As the constraints of robot's work-space, configuration and singularity can be described by the geometry of robot's workspace, the kinematic feasibility of a planned trajectory call be tested through workspace's geometry. Due to the complexity of the general case a robot manipulator with six revolute joints (6R) is selected as the case study in this paper. As a result, any point along a planned Cartesian trajectory can be determined whether it is inside the robot's workspace, if it is in the region of singularity, and be provided with the suitable robot configurations.

Journal ArticleDOI
TL;DR: Loads simulating forces that the robot is subjected to in actual cases were applied to the robot in different robot configurations and the elastic compliance and deformation patterns of each joint and link were obtained.
Abstract: Compliance of a revolute robot manipulator is studied experimentally by holographic interferometry using a pulsed ruby laser. In the analysis, loads simulating forces that the robot is subjected to in actual cases were applied to the robot in different robot configurations. Thereby, the elastic compliance and deformation patterns of each joint and link were obtained. Experiments were performed on the ASEA IRb/6. The great influence of load-induced effects on accuracy were verified. The results provide a sound basis for corrective measures intended to minimize these effects. Holographic interferometry provides an extremely reliable way of revealing the 3-D behavior of a robot under load.

Proceedings ArticleDOI
24 Apr 1988
TL;DR: Both the direct and inverse kinematics and statics are solved completely and the quasistatics of the stable grasping of an object by a planar two-fingered robotic gripper are considered.
Abstract: The kinematics and the quasistatics of the stable grasping of an object by a planar two-fingered robotic gripper are considered. The object is assumed to be quasistatically manipulated in a fine-motion manufacturing work space while experiencing external forces and moments. Each finger is assumed to be a generalized two-axis revolute robot manipulator moving in harmony with another similar robot situated nearby. The quasistatics of the object are directly related to four-joint torques for servo-control purposes. Both the direct and inverse kinematics and statics are solved completely. >

01 Dec 1988
TL;DR: This work addresses the control of n-link, serial, spatial robotic systems modeled with m1 joint and m2 link flexibilities such that n≥m1 +m2 .
Abstract: The current practice of controller development for flexible robotic systems generally focuses on one-link robotic arms and is valid for small oscillations. This work addresses the control of n-link, serial, spatial robotic systems modeled with m1 joint and m2 link flexibilities such that n≥m1 +m2 . System compliance is modeled by local springs and nonactuated prismatic and revolute type pseudo joints. The coupled, nonlinear, error-driven system equations are derived for the complete model without linearization or neglecting certain terms. For this system, the complete accessibility of vibrations is studied by orthogonal projections. It is shown that under some configurations of a robotic system, the induced oscillations may not be accessible to the controller. Given accessibility, the controller developed in this work assures the global asymptotic stability of the system. Example numerical simulations are presented based on the model of a six-degree-of-freedom Cincinnati Milacron T3-776 industrial robot. One example models the system compliance in four joints, while another case study simulates four lateral link oscillations. These examples show that this controller, even under inaccurate payload description, eliminates the oscillations while tracking desired trajectories.

Proceedings ArticleDOI
08 Aug 1988
TL;DR: The dynamics and control problems of the robot are discussed and a control strategy which may be easily realized in engineering practice because of an efficient real-time control algorithm is proposed.
Abstract: DGR-5A Robot designed by us is an articulated one with five revolute joints driven by electrical servomotors. This paper discusses the dynamics and control problems of the robot.Various dynamic parameters of each link are computed in detail. After deriving a set of dynamic equations and analysing the dynamio behaviour, we proposed a control strategy which may be easily realized in engineering practice because of an efficient real-time control algorithm. The simulation results of the control strategy for DGR-SA robot were rather satisfactory and encouraging.

01 Nov 1988
TL;DR: The use of the ATB model as a robot dynamics simulation tool is discussed and various simulations are demonstrated to serve as valuable tools for analyzing robotic mechanisms, dynamic effects, joint load transmissions, feed-back control algorithms employed in the actuator control and end-effector trajectories.
Abstract: The Articulated Total Body (ATB) model is a computer sumulation program which was originally developed for the study of aircrew member dynamics during ejection from high-speed aircraft. This model is totally three-dimensional and is based on the rigid body dynamics of coupled systems which use Euler's equations of motion with constraint relations of the type employed in the Lagrange method. In this paper the use of the ATB model as a robot dynamics simulation tool is discussed and various simulations are demonstrated. For this purpose the ATB model has been modified to allow for the application of torques at the joints as functions of state variables of the system. Specifically, the motion of a robotic arm with six revolute articulations with joint torques prescribed as functions of angular displacement and angular velocity are demonstrated. The simulation procedures developed in this work may serve as valuable tools for analyzing robotic mechanisms, dynamic effects, joint load transmissions, feed-back control algorithms employed in the actuator control and end-effector trajectories.

Patent
22 Nov 1988
TL;DR: In this article, an incorrect positioning of a vehicle due to non-ideal geometric relations is compensated by using the inverse Jacobi matrix of the coordinate transformation equation system with the vector of the incorrect positioning ( DELTA x), so that the error-compensated axis angle positions (theta f) are obtained from the sum of the temporary angular positions ( theta v) and of the correction values (delTA theta ).
Abstract: In the said method an incorrect positioning ( DELTA x) of the vehicle due to non-ideal geometric relations is compensated in that in a first step (I) temporary angular positions theta v are determined when the tool position (x) and the parameter vector ( phi ref), which describes the geometric relations of the robot are prescribed in that in a second step (II) the positioning error ( DELTA x) is determined quantatively by means of error calculation, in that in a third step (III) correction values of the axis angle positions ( DELTA theta ) are calculated by multiplication of the inverse Jacobi matrix of the coordinate transformation equation system with the vector of the incorrect positioning ( DELTA x), so that in a fourth step (IV) the error-compensated axis angle positions ( theta f) are obtained from the sum of the temporary angular positions ( theta v) and of the correction values ( DELTA theta ). … …

Proceedings ArticleDOI
Kang Sun1, V. Lumelsky
08 Aug 1988
TL;DR: A unified theoretical framework is presented in this paper, which allows one to use one scheme for any of the many possible configurations of simple arm manipulators with revolute and prismatic (sliding) joints.
Abstract: Until recently, the problem of path planning for a robot arm operating among unknown obstacles has been treated on a case-by-case basis with different algorithms for different arm kinematics. A unified theoretical framework is presented in this paper, which allows one to use one scheme for any of the many possible configurations of simple arm manipulators with revolute and prismatic (sliding) joints.