Redundant Inverse Kinematics System for Obstacles Avoidance (original) (raw)
Related papers
Redundant manipulator for obstacle avoidance and inverse kinematics solution by least squares
1993
An 8 degree-or-freedom (DOF) redundant manipulator is designed and realized for uses in robot-human environments requiring obstacle avoidance. The extra two DOF provides the flexibility in kinematics for obstacle avoidance. The modular mechanical structure associates both simple mechanical construction and an easy forward kinematics solution. A motor-control module is implemented to perform a constant acceleration motion in accordance with the commands from a host computer. The inverse kinematics solution of the redundant manipulator is introduced by using the forward kinematics with the recursive least squares estimation (RLSE) method. The RLSE method is applied for the linearized model of the nonlinear kinematics around the operating point
Kinematic control algorithms for on-line obstacle avoidance for redundant manipulators
2003
The paper deals with kinematic control algorithms for on-line obstacle avoidance which allow a kinematically redundant manipulator to move in an unstructured environment without colliding with obstacles. The presented approach is based on the redundancy resolution at the velocity level. The primary task is determined by the end-effector trajectories and for the obstacle avoidance the internal motion of the manipulator is used. The obstacle avoiding motion is defined in onedimensional operational space and hence, the system has less singularities what makes the implementation easier. Instead of the exact pseudoinverse solution we propose an approximate one which is computationally more efficient and allows also to consider many simultaneously active obstacles without any problems. The fast cycle times of the numerical implementation enable to use the algorithm in real-time control. For illustration some simulation results of highly redundant planar manipulator moving in an unstructured and time-varying environment and experimental results of a four link planar manipulator are given.
SN Applied Sciences
This paper presents an optimization-based approach for solving the inverse kinematics problem of spatial redundant manipulators in cluttered workspaces. To provide better flexibility and manipulability in the narrow regions, the joints were modeled with multiple degrees of freedom (DOF) and are considered as universal joints. Each universal joint has two orthogonal DOF, which are made by pitch axis and yaw axis. The inverse kinematic (IK) problem is multimodal by nature, and it has multiple solutions. A global search and multi-start framework have been implemented to determine the multiple kinematic configurations for a given task location. The characteristic feature of the IK problem has multiple configurations for a given task space location. The process of determining the best from multiple solutions is called redundancy resolution. Secondary criteria such as joint distance minimization and collision avoidance have been chosen to perform the task of redundancy resolution. A classical constrained optimization technique has been implemented to perform the tasks of inverse kinematics and redundancy resolution. The collision avoidance scheme was implemented with a collision detection algorithm by using a bounding box approach. Simulations were performed for 9-DOF spatial manipulators with 3D obstacles in the workspace. Results are reported on IK, multiple IK solutions, and redundancy resolution of the robot in an unconstrained and cluttered environment. Results show that the proposed method is accurate and computationally efficient in determining the IK solution of spatial redundant manipulators in a multi-obstacle and restricted environment.
A Novel Approach for a Inverse Kinematics Solution of a Redundant Manipulator
Applied Sciences, 2018
Kinematically-redundant manipulators present considerable difficulties, especially from the view of control. A high number of degrees of freedom are used to control so-called secondary tasks in order to optimize manipulator motion. This paper introduces a new algorithm for the control of kinematically-redundant manipulator considering three secondary tasks, namely a joint limit avoidance task, a kinematic singularities avoidance task, and an obstacle avoidance task. For path planning of end-effector from start to goal point, the potential field method is used. The final inverse kinematic model is designed by a Jacobian-based method considering weight matrices in order to prioritize particular tasks. Our approach is based on the flexible behavior of priority value due to the acceleration of numerical simulation. The results of the simulations show the advantage of our approach, which results in a significant decrease of computing time.
Collision Avoidance Methods of Redundant Robot Arms: A review of the suggested solutions
Several novel methods of solving the inverse kinematics of collision avoidance are reviewed in this report, covering iterative and non-iterative solutions, both in real-time and predetermined. Different collision detection algorithms were presented which use hulls, multiple boundaries, collision points, ellipses, and potential fields while reviewing their relative drawbacks such as non-convergence, local minimum, high calculation costs, inefficient paths, and no support for realtime path modification.
Obstacle Avoidance for Kinematically Redundant Manipulators in Dynamically Varying Environments
The International Journal of Robotics Research, 1985
The vast majority of work to date concerned with obstacle avoidance for manipulators has dealt with task descriptions in the form ofpick-and-place movements. The added flexibility in motion control for manipulators possessing redundant degrees offreedom permits the consideration of obstacle avoidance in the context of a specified end-effector trajectory as the task description. Such a task definition is a more accurate model for such tasks as spray painting or arc welding. The approach presented here is to determine the required joint angle rates for the manipulator under the constraints of multiple goals, the primary goal described by the specified end-effector trajectory and secondary goals describing the obstacle avoidance criteria. The decomposition of the solution into a particular and a homogeneous component effectively illustrates the priority of the multiple goals that is exact end-effector control with redundant degrees of freedom maximizing the distance to obstacles. An efficient numerical implementation of the technique permits sufficiently fast cycle times to deal with dynamic environments.
A motion planning based approach for inverse kinematics of redundant robots: the kinematic roadmap
1997
We propose a new approach to solving the point-to-point inverse kinematics problem for highly redundant manipulators. It is inspired by recent motion planning research and explicitly takes into account constraints due to joint limits and self-collisions. Central to our approach is the novel notion of kinematic roadmap for a manipulator. The kinematic roadmap captures the connectivity of the configuration space of a manipulator in a finite graph like structure. The standard formulation of inverse kinematics problem is then solved using this roadmap. Our current implementation, based on Ariadne's clew algorithm, is composed of two sub-algorithms: EXPLORE, a simple algorithm that builds the kinematic roadmap by placing landmarks in the configuration space; and SEARCH, a local planner that uses this roadmap to reach the desired end-effector configuration. Our implementation of SEARCH is an extremely efficient closed form solution, albeit local, to inverse kinematics that exploits the serial kinematic structure of serial manipulator arms. Initial experiments with a 7-DOF manipulator have been extremely successful
Iterative strategies for obstacle avoidance of a redundant manipulator
WSEAS Transactions on Mathematics, 2010
This paper presents four different iterative strategies for obstacle avoidance of a redundant manipulator. The end-effector task consists in generating the references along the contour of a curve. The proposed strategies are iterative in the sense that the joint configuration computed in the previous step represents the current point around which the methods provide the next joint configuration corresponding to the imposed end-effector posture. The objective of the strategies is to simultaneously minimize the endeffector location error and the manipulator total joint displacement while the collision with the obstacle is avoided. The strategies are implemented using the Matlab software and the comparative simulation results are obtained for a planar redundant manipulator with four degrees of freedom and with its end-effector following the contour of a circle, whose surface is considered to be restrictive for all elements of the manipulator.
2009
This paper presents a new approach for collision avoidance of manipulators. When the workspace is completely mapped and the obstacles are known, it is possible to define the task considering the presence of obstacles or their proximity can be monitored simply by the inverse kinematics resolution of the complete system. However, when the workspace is poorly mapped/unstructured and/or time-varying, it is necessary to rely on sensor information to monitor proximity of obstacles and, consequently, define a suitable collision avoidance strategy. This kind of environment is increasingly common in recent robotic applications, and the use of kinematic redundant manipulators is considered, because of increased dexterity. There are being developed different strategies to address this problem, and the literature presents different kinds of sensors and their use to detect the proximity of an obstacle. These strategies use the more traditional pseudo-inverse methods to solve the inverse kinematics of the redundant kinematic chain. In this work, it will be shown the kinematic constraints method as an alternative to solve the inverse kinematics. This method is based on screw theory, the Kirchhoff-Davies method and virtual chains. Among other advantages over the pseudo-inverse methods, the kinematic constraints method is dimensional consistent and conserves movement. An example is used to illustrate the method and its main characteristics.