Hyper-redundant Manipulator Research Articles

An Experimental Study on a SMA Driven Pressurized Hyper-redundant Manipulator

This study describes the design and fabrication of a pressurized hyper-redundant manipulator driven by high strain shape memory alloy (SMA) actuators. Hyper-redundant devices are characterized by repeating independently controlled structures connected in series; their architecture is comparable to that of a snake or worm. The proposed design is composed of four identical modules; each providing three degrees of freedom from three symmetrically positioned actuators. The manipulator stiffness and actuator return-force are controlled by pressurized air, injected at the base of the manipulator. Tests on a single unit module have demonstrated that the design could achieve rotations of over 50° and displacements of over 40% at a frequency of 1/20 Hz.

A new spatial hyper-redundant manipulator

This work presents a novel hyper-redundant manipulator. Such a manipulator is built with a variable number of tandem-assembled modules. Each module consists of a 3-dof parallel manipulator with asymmetric extremities in which moving platform possesses mixed motions with respect to the base platform. The manipulator's architecture is so simple that the forward position analysis is presented in closed-form solution, more specifically, in echelon-form solution. On the other hand, the velocity and acceleration analyses are carried out using the theory of screws. Finally, a case study consisting of solving the kinematic analysis of a 30-dof hyper-redundant manipulator is presented.

A variational approach to path planning for hyper-redundant manipulators

Motion planning for hyper-redundant manipulators in a complicated and cluttered workspace is a challenging problem. Many of the path planning algorithms, based on cell decomposition or potential field, fail due to the high dimensionality and complex nature of the C-space. Probabilistic roadmap methods (PRM) which have been proven to be successful in high dimensional C-spaces suffer from the drawback of generating paths which involve a lot of redundant motion. In this paper, we propose a path optimizing method to improve a given path in terms of path length and the safety against the collisions, using a variational approach. The capability of variational calculus to optimize a path is demonstrated on a variety of examples. The approach succeeds in providing a good quality path even in high dimensional C-spaces.

Motion Control of Hyper Redundant Robots with Learning Control Based on Linear Combination of Error History and Acquisition of Initial Configuration with Backward Learning

This paper describes the motion control of hyper redundant robots with a learning control scheme based on linear combination of error history. For a hyper redundant serial manipulator to achieve the motion of its end effector as a main task with a number of additional motions of other links as subtasks, several effective methods to set subtasks are proposed. The objectives of these methods are to reduce the interference between main task and subtasks, and to prevent from partially singular configuration of the manipulator. The backward learning scheme is also proposed to obtain the optimum initial configuration. Several simulations and experiments with a planar 10 R serial manipulator reveal that the proposed methods are effective and useful.

A fast workspace-density-driven inverse kinematics method for hyper-redundant manipulators

Hyper-redundant manipulators have a very large number of redundant degrees of freedom. They have been recognized as a means to improve manipulator performance in complex and unstructured environments. However, the high degree of redundancy also poses new challenges when performing inverse kinematics calculations. Prior works have shown that the workspace density (generated by sampling the joint space and evaluating the frequency of occurrence of the resulting end-effector reference frames) is a valuable quantity for use in ${\cal O}(P)$ inverse kinematics algorithms. Here $P$ is the number of modules in a manipulator constructed of a serial cascade of modules. This paper develops a new “divide-and-conquer” method for inverse kinematics using the workspace density. This method does not involve a high-dimensional Jacobian matrix and offers high accuracy. And its computational complexity is only ${\cal O}({\rm log}_2\,P)$, which makes it ideal for very high degree-of-freedom systems. Numerical simulations are performed to demonstrate this new method on a planar example, and a detailed comparison with a breadth-first search method is conducted.

Implementation and Kinematic Control of a Hyper-redundant Mobile Manipulator System

Redundant or hyper-redundant mobile manipulator can give lots of assistance to astronauts in space station. The design and implementation of a hyper redundant mobile manipulator system are described, which is composed of an 8 DOF module robot and a 1 DOF motorized rail. Inverse kinematic resolution of the system is discussed and one simplified control method based on joint limit avoidance and configuration optimization is proposed. Simulation and experimental results are presented.

1313 24超多自由度マニピュレータの部分的特異姿勢の評価とそれに基づく運動制御(OS3-1 機構の開発とシミュレーション(1))

1313 24超多自由度マニピュレータの部分的特異姿勢の評価とそれに基づく運動制御(OS3-1 機構の開発とシミュレーション(1))

Hyper redundant manipulator using compound three-bar linkages

A new mechanism for hyper redundant manipulator (HRM) is presented, which comprises of serially assembled compound three-bar linkages (CTL) The CTL mechanism has some Unique properties This paper presents the forward and Inverse kinematics of this mechanism and shows the simulation of the HRM havig 9 CTL units The recursive algorithm of the ,"verse kinematics that the author originally developed is employed It is fast and stable, moreover, It enables us to obtain a solution in which the end-point of the HRM is controlled by a portion of Joints It also presents the method of the dynamical analysis There exist kinematical constraints in the proposed closed linkage mechanism. In the dynamic analysis constraints are sufficiently sustained by the constraint stabilization method that the author developed The mechanical structure of the HRM having some CTL units that is under construction is shown

IMMUNOLOGY-BASED MOTION CONTROL FOR MODULAR HYPER-REDUNDANT MANIPULATORS

Artificial Immune System (AIS) has recently been actively researched with a number of emerging engineering applications that has capitalized from its characteristics including self-organization, distributive control, knowledge mapping and fault tolerance. This paper reports the application of the existing AIS paradigm for the distributive control of a modular multi-jointed, hyper-redundant manipulator. Modular robot usually implemented with simplified mathematical model to cope with the scenario of limited computation power and memory. In this paper, we investigate the viability of a multiagent immunology–based motion control for the trajectory control of modular hyper-redundant manipulators.

Workspace Generation of Hyper-Redundant Manipulators as a Diffusion Process on<tex>$SE(N)$</tex>

Hyper-redundant manipulators have a large number of redundant degrees of freedom. They have been recognized as a means to improve manipulator performance in complex and unstructured environments. However, the high degree of redundancy also causes difficulty in the calculation of workspaces and inverse kinematics. This paper develops a diffusion-based algorithm for workspace generation of hyper-redundant manipulators. This algorithm makes the workspace generation problem as simple as solving a diffusion equation which has an explicit solution. This diffusion equation is a partial differential equation defined on the motion group SE(N), and describes the evolution of the workspace density function, depending on manipulator length and kinematic properties. This paper also solves the inverse kinematics problem in an elegant way by dividing the manipulator into virtual segments and cascading the corresponding workspace densities generated by the diffusion equation.

Dynamic Control of Curve-Constrained Hyper-Redundant Manipulators

Hyper-redundant manipulators have high number of kinematic degrees of freedom, and possess unconventional features such as the ability to enter narrow spaces while avoiding obstacles. To control these hyper-redundant manipulators accurately, manipulator dynamics should be considered. This is, however, time-comsuming and makes implementation of real-time control difficult. In this paper, we propose a dynamic control scheme for hyper-redundant manipulators, which is based on analysis in defined posture space where three parameters were used to determine the manipulator posture. Manipulator dynamics are modeled on the parameterized form with the parameter of the posture space path. The posture space path-tracking feed-forward controller is then formulated on the basis of a parameterized dynamic equation. Computer simulation, in which a hyper-redundant manipulator traces the posture space path well by using the proposed feed-forward controller, proved that the hyper-redundant manipulator tracks the workspace path accurately.

Design and study of a novel hyper-redundant manipulator

A novel hyper-redundant manipulator named RT1 is presented in this paper. The key feature of RT1 is that all degrees of freedom (DOF) are actuated with only one motor, via specially designed hinge bar universal joints. The mechanism of RT1 which includes a special hinge bar universal joint, bend structure and motion diversion structure is described. RT1 is a discrete manipulator; the discrete working space is described, and the parameter optimization for kinematical redundancy resolution is also studied. In selecting the unit increment of joints angles as an optimizing parameter, the criterion used is to alter the design parameter as little as possible during the manipulator's motion from the initial to the expected position.

Obstacle Avoidance for Spatial Hyper‐Redundant Manipulators Using Harmonic Potential Functions and the Mode Shape Technique

AbstractThis paper deals with the obstacle avoidance problem for spatial hyper‐redundant manipulators in known environments. The manipulator is divided into two sections, a proximal section that has not entered the space among the obstacles and a distal section among the obstacles. Harmonic potential functions are employed to achieve obstacle avoidance for the distal section in three‐dimensional space in order to avoid local minima in cluttered environments. A modified panel method is used to generate the potential of any arbitrary shaped obstacle in three‐dimensional space. An alternative backbone curve concept and an efficient fitting method are introduced to control the trajectory of proximal links. The fitting method is recursive and avoids the complications involved with solving large systems of nonlinear algebraic equations. The combination of a three‐dimensional safe path derived from the harmonic potential field and the backbone curve concept leads to an elegant kinematic control strategy that guarantees obstacle avoidance. © 2003 Wiley Periodicals, Inc.

Control of a multijoint manipulator "Moray arm"

We introduce a multijoint manipulator that was named which is a slider-integrating multijoint manipulator, where a powerful slider is installed at the base of the arm. The Moray emulates the motion of a Moray, thus, allowing it to easily enter a narrow space while avoiding obstacles. To elucidate the features of the Moray arm, we present new control methods named and two-degrees-of-freedom (2-DOF) Moray drive. The Moray drive control generates rotating motion of the joints in synchronization with linear motion of the slider while restricting the on the trajectory. The 2-DOF Moray drive control reduces the control problem of the hyper DOFs to the simple one of 2-DOFs: one of the control variables signifies the linear combination of the objective initial and final postures of the arm, while another expresses the amount of the pull-out-displacement when pulling the out of the housing. The properties of Moray controlled by Moray drive or 2-DOF Moray drive are described. Based on the 2-DOF Moray drive control, we also propose an obstacle avoidance scheme for the arm to perform a pick-and-place task while avoiding the existing static obstacles in environment. The scheme is based on the posture space analysis and generates the obstacle collision-free trajectory in the posture space. From the simulation result, we conclude that the Moray controlled by the proposed schemes gives great possibility for the hyper-redundant manipulator to perform applications such as maintenance of nuclear reactors, collection of lumps of existing manganese under sea, and care of patients.

An improved inverse kinematic and velocity solution for spatial hyper-redundant robots

A new and efficient kinematic position and velocity solution scheme for spatial hyper-redundant manipulators is presented. The manipulator's arm has discrete links and universal joints. Backbone curve concepts and a modal approach are used to resolve the manipulator's redundancy. The effects of the mode shapes and the slope of the backbone curve at the starting point on the workspace are studied. It is shown that the usage of conventional mode shapes limits the workspace of the hyper-redundant arm. By introducing new mode shapes, an improved workspace is obtained. A simple and efficient recursive fitting method is introduced to avoid complications involved with solving systems of nonlinear algebraic equations. This method also guarantees the existence of solutions for the inverse kinematic problem at the velocity level. Velocity properties of the backbone curve are investigated and the inverse velocity propagation is solved for the spatial hyper-redundant arm. The velocity propagation scheme is recursive and is efficiently applicable to any number of links.

A general solution for the position, velocity, and acceleration of hyperredundant planar manipulators

AbstractA new approach for the solution of the position, velocity, and acceleration of hyperredundant planar manipulators following any twice‐differentiable desired path is presented. The method is singularity free, and provides a robust solution even in the event of mechanical failure of some of the robot actuators. The approach is based on defining virtual layers, and dividing them into virtual/real three‐link or four‐link subrobots. It starts by solving the inverse kinematic problem for the subrobot located in the lowest virtual layer, which is then used to solve the inverse kinematic equations for the subrobots located in the upper virtual layers. An algorithm is developed that provides a singularity‐free solution up to the full extension through a configuration index. The configuration index can be interpreted as the average of the determinants of the Jacobians of the subrobots. The equations for the velocities and accelerations of the manipulator are solved by extending the same approach, and it is shown that the value of the configuration index is critical in maintaining joint velocity continuity. The inverse dynamic problem of the robot is also solved to obtain the torques required for the robot actuators to accomplish their tasks. Computer simulations of several hyperredundant manipulators using the proposed method are presented as numerical examples. © 2002 John Wiley & Sons, Inc.

Fault Adaptive Kinematic Control Using Multiprocessor System and its Verification Using a Hyper-redundant Manipulator

Decentralized autonomous control architecture and self-organizing control architecture have several advantages in space robots, the most fascinating of which is an adaptation for partial faults. The Communications Research Laboratory have proposed an ""Orbital Maintenance System"" (OMS) that maintains a space system. We have developed a modular manipulator, which can be controlled by distributed processors in each module and can overcome partial failures. In this paper, we introduce a decentralized control algorithm for modular manipulators and discuss its performance in computer simulations and experiments. The algorithm proved useful for inspection in modular manipulators, and robust to partial faults.

805 能動大腸内視鏡の開発 : 第1報 要求機能の検証および試作機の製作(感覚・計測とロボティクス・メカトロニクスI)(OS.12 感覚・計測とロボティクス・メカトロニクス)

We develop an active colonoscopy system for realizing easy medical operation. In this report, we discuss required functions and specifications for the active colonoscopy system, and construct a prototype. 0ur proposed system is like a hyper redundant manipulator, which consists of plural units. Each unit consists of one actuated joint and two links, and control system is contained in the units. FSR(Force Sensing Resister) is also equipped as a tactile sensor for detecting the collision with colon. Using our prototype, we have basic experiments with a colon-shaped tube model and confirm the validity of the system.

超冗長マニピュレータの伸縮動作式分散制御法 位置決め制御則と平面マニピュレータへの適用

A distributed control method for hyper-redundant manipulators is proposed, aiming at applying to complicated and unknown or dynamic environment. A manipulator consists of serially connected joint units, and each unit has the same degrees of freedom as dimension of task space. The proposed method is highly distributed: each unit is controlled by one controller, only neighboring units communicate with each other, and each unit does not have to obtain information from far units. The method is multiple point control: not only the end-effector but also several units can converge to their own desired positions stably. Thus the manipulator can avoid obstacles only if the units which detect the obstacles with their own proximity sensors set their desired positions far from the obstacles. The manipulator makes expansion and contraction motion; it can move into/out of long and narrow space like pipes. All units are controlled so that their displacements may be equal. Hence they have the same and maximum displacement margin. The dynamics of the end-effector is not influenced by the motion of units; that is important for doing tasks with the end-effector. The proposed method is applied to a planar hyper-redundant manipulator with rotational joints, and the effectiveness and usefulness of the method are ascertained by computer simulations and experiments.

Minimum-time control of coupled tendon-driven manipulators

Hyper-redundant manipulators have very large degrees of redundancy, thus possessing unconventional features such as the ability to enter a narrow space while avoiding obstacles. In this study, a time-optimal control scheme is proposed for a hyper-redundant manipulator that was realized by coupled tendon-driven mechanisms. In the mechanisms, a pair of tendons for driving a joint is pulled from base actuators via pulleys mounted on the base-side joints and the degrees of actuation redundancy exist. The time-optimal trajectory planning problem is solved by using the phase-plane analysis and the linear programming technique. Computer simulations were also performed to show that the proposed scheme makes full use of the actuation redundancy of tendons and their coupled function to shorten motion time.