Hyper-redundant Robot Research Articles

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.

Modeling and adaptive control of redundant robots

This paper presents an adaptive control scheme for a hyper-redundant robot articulated nimble adaptable trunk (ANAT) subject to spatial constraints. An optimization scheme is applied to avoid obstacles in 3D space present in the robot's trajectory by using redundancy, and to prevent the robot from retracting and crashing into the base by setting a security envelop. The generation of the trajectory with obstacles avoidance is performed by calculating the differential inverse kinematics of the robot based on the generalized inverse function. The obstacles are modeled by hyper-surfaces in order to reduce calculations and improve the computation time. When the optimal trajectory is attained in presence of the imposed constraints, an adaptive control law is applied to the robot. Simulation results showed the effectiveness of the proposed approach.

4204 超多自由度ロボットの自由度の有効使用の評価と運動制御への適用(S68-1 機構の開発とシミュレーション(1),S68 機構の開発とシミュレーション)

This paper describes a new method to evaluate effective utilization of redundancy of hyper redundant robots based on movability of each joint and assist ability for given target motions. Two evaluation indices were proposed based on the distribution of column vectors of Jacobian matrix. Several motion control methods to simultaneously maximize movability and assist ability with the learning control based on linear combination of error history were proposed and were examined with several simulations with a 10R planar serial manipulator. The results revealed that the proposed methods were effective and useful.

Three degrees-of-freedom joint for spatial hyper-redundant robots

We present a new mechanical design for a compact three degrees-of-freedom joint mechanism. This joint design is ideal for use in robotic devices, especially hyper-redundant or snake-like robots. This joint exhibits an unprecedented range of motion: the origin of a coordinate frame attached to the output link of the joint can move on a spherical cone whose apex angle is 120° and this coordinate frame can be rotated around an axis passing through its origin and the center of the sphere. Moreover, the joint is optimized for strength, compactness and accuracy. These characteristics are verified by exploring the magnitude of the wrenches and errors that the joint can produce in its effective workspace. Finally, we present a mechatronic integration of four of our joints to construct a 12 degrees-of-freedom spatial hyper-redundant robot.

Design and control of a mobile hyper-redundant urban search and rescue robot

In this work we introduce a new concept of a search and rescue robotic system that is composed of a hyper-redundant robot (HRR) which is mounted on a mobile base. This system is capable not only of inspecting areas reachable by the mobile base, but also of inspecting unreachable areas such as small cracks and pipes, using the camera and sensors mounted on its end-effector. The HRR is composed of 14 actuated, serially chained, d.o.f. which have been designed for compactness, yet each is strong enough to support the entire robot structure. The low-level control system of the robot incorporates 14 embedded mini-circuit boards implementing a low number of wires and highspeed, I2C data bus technology. The high-level control algorithms implement kinematic methods to perform on-line motion control both in a global coordinate frame and in the camera coordinate frame for which a camera is mounted on the robot end-effector. The user interface allows the user full and easy control and interpretation of the data received from the camera. All the components of the system are hose-able as required by search and rescue regulations. Finally, we describe the integration of all the above-mentioned components in a complete operational mobile hyper-redundant search and rescue robotic system. This system has been deployed and tested in several search and rescue training scenarios.

2813 誤差履歴線形和学習制御則に基づく超多自由度ロボットの運動制御 : 後退学習による運動開始姿勢の獲得(S59 機構の開発とシミュレーション)

2813 誤差履歴線形和学習制御則に基づく超多自由度ロボットの運動制御 : 後退学習による運動開始姿勢の獲得(S59 機構の開発とシミュレーション)

超多自由度ロボットの機構と制御(機械設計)

超多自由度ロボットの機構と制御(機械設計)

低自由度ユニットを直列接続した超多自由度ロボットの運動制御(S49-1 パラレルメカニズムとその応用(1),S49 パラレルメカニズムとその応用)

低自由度ユニットを直列接続した超多自由度ロボットの運動制御(S49-1 パラレルメカニズムとその応用(1),S49 パラレルメカニズムとその応用)

2706 低自由度ユニットを直列接続した超多自由度ロボットの運動解析

This paper describes kinematic analysis of hyper redundant robot built by serially connecting with many units with a few DOF. Each unit is a spatial parallel mechanism with 3 DOF and is composed of 2 stages connected with 3 linearactuators, 7 spherical joints and a center rod. Direct kinematic analysis was carried by solving a system of nonlinear equations on posture angles of a stage. The Jacobian matrix is derived from the derivatives of the equations. Two kinds of inverse kinematic analyses were carried out. The one was to obtain the input velocities whose square norm is minimum by using pseudoinverse of Jacobian matrix. The other was to carry out the iterative calculation so as to converge output error while output displacement was evenly distributed into each unit. Several simulation results of direct and inverse kinematics were illustrated.

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.

The dexterity and singularities of an underactuated robot

AbstractUnderactuated robots are robotic systems with more joints than actuators. A robot may be underactuated by design as in the case of a hyper‐redundant robot with passive joints or may become underactuated as a result of an actuator failure. In this article, we examine the dexterity of underactuated robots whose passive joints operate in either a locked or free‐swinging mode. The ability to an analyze the dexterity of an underactuated robot has important applications especially for the control of passive joints with brakes and for the fault tolerance analysis of an otherwise fully actuated kinematically redundant robot. The approach applied here is to use kinematics and dynamics‐based formulations of manipulator dexterity. We then characterize passive‐joint singularities, i.e., configurations where full end‐effector control is lost because one or more joints are passive instead of active. Lastly, we introduce a new characterization of joint‐limit singularities, which are configurations where full end‐effector control cannot be achieved because one or more joints are at their joint limits. © 2001 John Wiley & Sons, Inc.

1P1-A1 多様な移動形態をもつ3次元超冗長ロボットの開発と制御 : 第2報 V字型形態による移動の実現(81. スーパーメカノシステムII)

1P1-A1 多様な移動形態をもつ3次元超冗長ロボットの開発と制御 : 第2報 V字型形態による移動の実現(81. スーパーメカノシステムII)

アクチュエータの駆動特性を考慮したモレイ型多関節ロボットアームの軌道追従制御

Hyper-redundant robot arms have a very large degrees of kinematic redundancy, thus possess the unconventional features such as ability to enter a narrow space while avoiding obstacles. In this paper, a time-optimal path-tracking control scheme with considering the actuation characteristics of actuators was introduced for the Moray arm, a slider-installed hyperredundant robot arm. Therein, the used actuators were assumed to be the commonly-used DC motors and the maximum heat generated by DC motor was considered as the limit actuation characteristics of actuator. The time-optimal trajectories for tracking the path in posture space were generated with subjection of the limit-heat characteristics. Computer simulations were also performed to show that, 1) the proposed control scheme considering the limit-heat characteristics makes all output of actuators within the heat bounds and all outputs are still under the maximum power curve, 2) the required output of actuators is continuous and no pulse torques are generated, in comparison with the traditional time-optimal control schemes subjected to torques and/or velocities.

Optimal control of manipulators with any number of passive joints

This article discusses the problem of controlling robot manipulators with passive joints, when the number of passive joints is larger than the number of active joints. Assuming that brakes and position sensors are available at each passive joint, we investigate the following issues: (1) what is a sufficient condition for controllability of the passive joints via dynamic coupling with the active joints and how can we quantify the controllability at a given configuration; (2) what is the optimal control and locking sequence of the passive joints; and (3) how can we control both passive and active joints to an equilibrium point in joint space. We propose an optimal control method and demonstrate its validity with both simulation and experimental results. The work presented here is significant because it provides a better understanding and a guideline for utilizing manipulators with passive joints for energy efficiency and fault-tolerant design in applications such as space robotics, hyperredundant robots, and sport mechanics. © 1998 John Wiley & Sons, Inc. 15: 115–129, 1998

Deflection characteristics of some special configurations of snake-type robots

The redundant robots analyzed here have large numbers of degrees of freedom. Such robots are analogous to snake or tentacles and are useful for operation in highly constrained environments and novel forms of locomotion — here it has been defined as critical manipulation. In this paper the end-point deflection of hyper-redundant robots have been studied by parameterization of the flexible links of the robot manipulator. A number of planar configurations of the redundant manipulator were taken into consideration for the present study and the configuration which gives minimum end-point deflection has been recommended for the critical manipulation. This work is significant for some of the research activities recently going on in NASA's Kennedy Space Center towards the application of hyper-redundant robots for manipulation inside the space Shuttle Cargo Bay.

The kinematics of hyper-redundant robot locomotion

This paper considers the kinematics of hyper-redundant (or serpentine) robot locomotion over uneven solid terrain, and presents algorithms to implement a variety of gaits. The analysis and algorithms are based on a continuous backbone curve model which captures the robot's macroscopic geometry. Two classes of gaits, based on stationary waves and traveling waves of mechanism deformation, are introduced for hyper-redundant robots of both constant and variable length. We also illustrate how the locomotion algorithms can be used to plan the manipulation of objects which are grasped in a tentacle-like manner. Several of these gaits and the manipulation algorithm have been implemented on a 30 degree-of-freedom hyper-redundant robot. Experimental results are presented to demonstrate and validate these concepts and our modeling assumptions.

Kinematically optimal hyper-redundant manipulator configurations

"Hyper-redundant" robots have a very large or infinite degree of kinematic redundancy. This paper develops new methods for determining "optimal" hyper-redundant manipulator configurations based on a continuum formulation of kinematics. This formulation uses a backbone curve model to capture the robot's essential macroscopic geometric features. The calculus of variations is used to develop differential equations, whose solution is the optimal backbone curve shape. We show that this approach is computationally efficient on a single processor, and generates solutions in O(1) time for an N degree-of-freedom manipulator when implemented in parallel on O(N) processors. For this reason, it is better suited to hyper-redundant robots than other redundancy resolution methods. Furthermore, this approach is useful for many hyper-redundant mechanical morphologies which are not handled by known methods.

A hyper-redundant manipulator

Hyper-redundant manipulators have a very large number of actuatable degrees of freedom. The benefits of hyper-redundant robots include the ability to avoid obstacles, increased robustness with respect to mechanical failure, and the ability to perform new forms of robot locomotion and grasping. The authors examine hyper-redundant manipulator design criteria and the physical implementation of one particular design: a variable geometry truss. >

A modal approach to hyper-redundant manipulator kinematics

This paper presents novel and efficient kinematic modeling techniques for hyper-redundant robots. This approach is based on a that captures the robot's macroscopic geometric features. The inverse kinematic, or hyper-redundancy resolution, problem reduces to determining the time varying backbone curve behavior. To efficiently solve the inverse kinematics problem, the authors introduce a approach, in which a set of intrinsic backbone curve shape functions are restricted to a modal form. The singularities of the modal approach, modal non-degeneracy conditions, and modal switching are considered. For discretely segmented morphologies, the authors introduce fitting algorithms that determine the actuator displacements that cause the discrete manipulator to adhere to the backbone curve. These techniques are demonstrated with planar and spatial mechanism examples. They have also been implemented on a 30 degree-of-freedom robot prototype. >

A Geometric Approach to Hyper-Redundant Manipulator Obstacle Avoidance

The term hyper-redundant refers to redundant manipulators with a very large or infinite number of degrees of freedom. These manipulators are analogous in morphology to snakes, elephant trunks, and tentacles. While a variety of obstacle avoidance algorithms for nonredundant and mildly redundant manipulators exist, little analysis has been performed for hyper-redundant robots. This paper presents a strictly geometric algorithm for hyper-redundant manipulator obstacle avoidance which relies on the use of “tunnels” in the obstacle-filled workspace. Methods of differential geometry are used to formulate equations which guarantee that sections of the manipulator are confined to the tunnels, and therefore avoid obstacles. A general formulation is presented with an example to illustrate this approach.