scholarly journals Kinematic-Model-Free Orientation Control for Robot Manipulation Using Locally Weighted Dual Quaternions

Robotics ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 76
Author(s):  
Ahmad AlAttar ◽  
Petar Kormushev
Keyword(s):  
Degrees Of Freedom ◽  
Position Control ◽  
Kinematic Model ◽  
Model Learning ◽  
Orientation Control ◽  
Dual Quaternions ◽  
Model Free ◽  
Novel Method ◽  
Model Free Controller ◽  
Three Degrees Of Freedom

Conventional control of robotic manipulators requires prior knowledge of their kinematic structure. Model-learning controllers have the advantage of being able to control robots without requiring a complete kinematic model and work well in less structured environments. Our recently proposed Encoderless controller has shown promising ability to control a manipulator without requiring any prior kinematic model whatsoever. However, this controller is only limited to position control, leaving orientation control unsolved. The research presented in this paper extends the state-of-the-art kinematic-model-free controller to handle orientation control to manipulate a robotic arm without requiring any prior model of the robot or any joint angle information during control. This paper presents a novel method to simultaneously control the position and orientation of a robot’s end effector using locally weighted dual quaternions. The proposed novel controller is also scaled up to control three-degrees-of-freedom robots.

scholarly journals Kinematic-Model-Free Redundancy Resolution Using Multi-Point Tracking and Control for Robot Manipulation

2021 ◽  
Vol 11 (11) ◽  
pp. 4746
Author(s):  
Ahmad AlAttar ◽  
Francesco Cursi ◽  
Petar Kormushev
Keyword(s):  
Degrees Of Freedom ◽  
Dynamic Models ◽  
Dynamic Properties ◽  
Kinematic Model ◽  
Redundancy Resolution ◽  
Model Learning ◽  
Model Free ◽  
Point Tracking ◽  
Hand Model ◽  
The Times

Robots have been predominantly controlled using conventional control methods that require prior knowledge of the robots’ kinematic and dynamic models. These controllers can be challenging to tune and cannot directly adapt to changes in kinematic structure or dynamic properties. On the other hand, model-learning controllers can overcome such challenges. Our recently proposed model-learning orientation controller has shown promising ability to simultaneously control a three-degrees-of-freedom robot manipulator’s end-effector pose. However, this controller does not perform optimally with robots of higher degrees-of-freedom nor does it resolve redundancies. The research presented in this paper extends the state-of-the-art kinematic-model-free controller to perform pose control of hyper-redundant robot manipulators and resolve redundancies by tracking and controlling multiple points along the robot’s serial chain. The results show that with more control points, the controller is able to reach desired poses in fewer steps, yielding an improvement of up to 66%, and capable of achieving complex configurations. The algorithm was validated by running the simulation 100 times, and it was found that, in 82% of the times, the robot successfully reached the desired target pose within 150 steps.

A Model of the Human Spine: Forward and Inverse Kinematics

1992 ◽  
Author(s):  
Sunil Kumar Agrawal ◽  
Siyan Li ◽  
Glen Desmier
Keyword(s):  
Range Of Motion ◽  
Inverse Kinematics ◽  
Degrees Of Freedom ◽  
Kinematic Model ◽  
Joint Angles ◽  
Human Spine ◽  
Forward And Inverse Kinematics ◽  
Position And Orientation ◽  
Three Degrees Of Freedom ◽  
Adjacent Vertebra

Abstract The human spine is a sophisticated mechanism consisting of 24 vertebrae which are arranged in a series-chain between the pelvis and the skull. By careful articulation of these vertebrae, a human being achieves fine motion of the skull. The spine can be modeled as a series-chain with 24 rigid links, the vertebrae, where each vertebra has three degrees-of-freedom relative to an adjacent vertebra. From the studies in the literature, the vertebral geometry and the range of motion between adjacent vertebrae are well-known. The objectives of this paper are to present a kinematic model of the spine using the available data in the literature and an algorithm to compute the inter vertebral joint angles given the position and orientation of the skull. This algorithm is based on the observation that the backbone can be described analytically by a space curve which is used to find the joint solutions..

Vertical Planar Underactuated Manipulation Using a Gravity Compensation Mechanism

2005 ◽  
Vol 17 (5) ◽  
pp. 553-559 ◽  
Author(s):  
Yoshiki Ono ◽  
◽  
Toshio Morita ◽  
Keyword(s):  
Degrees Of Freedom ◽  
Position Control ◽  
Equilibrium Points ◽  
Gravity Compensation ◽  
Compensation Mechanism ◽  
Angular Variation ◽  
Underactuated Manipulator ◽  
Zero Equilibrium ◽  
Three Degrees Of Freedom ◽  
Active Base

We propose generating and erasing equilibrium points for passive joints, together with an underactuated manipulator having both vertical and horizontal planar type. This manipulator implements three degrees of freedom (DOF) by combining a passive two-DOF mechanical gravity canceller and an active base joint. Equilibrium points are erased and adjusted by angular variation of the base joint so equilibrium points are erased when gravity torque is zero. If gravity torque is not zero, equilibrium points depend on angular variation of the base joint. Experimental results show position control of the distal link through the mechanical gravity canceller is effective for underactuated manipulation.

Numerical Analysis of the Grasp Configuration of a Planar 3-DOF Linkage-Driven Underactuated Finger

2012 ◽  
Vol 8 (2) ◽  
Author(s):  
Hamed Khakpour ◽  
Lionel Birglen
Keyword(s):  
Numerical Analysis ◽  
Dynamic Simulation ◽  
Degrees Of Freedom ◽  
Joint Angles ◽  
Final Configuration ◽  
Contact Points ◽  
Novel Method ◽  
Three Degrees Of Freedom ◽  
Underactuated Finger ◽  
Simulation Package

This paper proposes a novel method to investigate the grasp sequence of an underactuated (a.k.a. adaptive) finger with three degrees of freedom but only one actuator and find its final configuration. This method considers the magnitude and the sign of the torques generated on the phalanges of the finger through the contact points. By using these torques as indices, the algorithm calculates the values of the joint angles during the grasping sequence until the finger reaches its final configuration. To illustrate the effectiveness of this method a class of a 3-DOF adaptive finger is chosen and analyzed and then, using the proposed methodology, its grasp configuration is calculated when grasping different fixed objects. Finally, simulations are repeated using a dynamic simulation package and the obtained results are compared to the proposed method. The results show that the method can properly estimate the final configuration of the grasp.

Model-Based Control of Three Degrees of Freedom Robotic Bulldozing

2013 ◽  
Vol 136 (2) ◽  
Author(s):  
Scott G. Olsen ◽  
Gary M. Bone
Keyword(s):  
Material Removal Rate ◽  
Material Removal ◽  
Control Algorithm ◽  
Degrees Of Freedom ◽  
Position Control ◽  
Removal Rate ◽  
Optimal Controller ◽  
Control Laws ◽  
Rule Based ◽  
Three Degrees Of Freedom

This brief paper investigates the control of a robotic bulldozing operation. Optimal blade position control laws were designed based on a hybrid dynamic model to maximize the predicted material removal rate of the bulldozing process. Experiments were conducted with a scaled-down robotic bulldozing system. The control laws were implemented with various tuning values. As a comparison, a rule-based blade control algorithm was also designed and implemented. The experimental results with the best optimal controller demonstrated a 33% increase in the average material removal rate compared to the rule-based controller.

Accuracy estimation of a stretch-retractable single section continuum manipulator based on inverse kinematics

2019 ◽  
Vol 46 (5) ◽  
pp. 573-580
Author(s):  
Hao Wang ◽  
GuoHua Gao ◽  
Qixiao Xia ◽  
Han Ren ◽  
LianShi Li ◽  
...  
Keyword(s):  
Inverse Kinematics ◽  
Degrees Of Freedom ◽  
Kinematic Model ◽  
Content Type ◽  
Kinematics Model ◽  
Six Degrees Of Freedom ◽  
Single Section ◽  
Motion Range ◽  
Continuum Manipulator ◽  
Three Degrees Of Freedom

Purpose The purpose of this paper is to present a novel stretch-retractable single section (SRSS) continuum manipulator which owns three degrees of freedom and higher motion range in three-dimension workspace than regular single continuum manipulator. Moreover, the motion accuracy was analyzed based on the kinematic model. In addition, the experiments were carried out for validation of the theory. Design/methodology/approach A kinematics model of the SRSS continuum manipulator is presented for analysis on bending, rotating and retracting in its workspace. To discuss the motion accuracy of the SRSS continuum manipulator, the dexterity theory was introduced based on the decomposing of the Jacobian matrix. In addition, the accuracy of motion is estimated based on the inverse kinematics and dexterity theory. To verify the presented theory, the motion of free end was tracked by an electromagnetic positioning system. According to the comparison of experimental value and theoretical analysis, the free end error of SRSS continuum manipulator is less than 6.24 per cent in the region with favorable dexterity. Findings This paper presents a new stretch-retractable continuum manipulator that the structure was composed of several springs as the backbone. Thus, the SRSS continuum manipulator could own wide motion range depending on its retractable structure. Then, the motion accuracy character of the SRSS continuum manipulator in the different regions of its workspace was obtained both theoretically and experimentally. The results show that the high accuracy region distributes in the vicinity of the outer boundary of the workspace. The motion accuracy gradually decreases with the motion position approaching to the center of its workspace. Research limitations/implications The presented SRSS continuum manipulator owns three degrees of freedom. The future work would be focused on the two-section structure which will own six degrees of freedom. Practical implications In this study, the SRSS continuum manipulator could be extended to six degrees of freedom continuum robot with two sections that is less one section than regular six degrees of freedom with three single section continuum manipulator. Originality/value The value of this study is to propose a SRSS continuum manipulator which owns three degrees of freedom and could stretch and retract to expend workspace, for which the accuracy in different regions of the workspace was analyzed and validated based on the kinematics model and experiments. The results could be feasible to plan the motion space of the SRSS continuum manipulator for keeping in suitable accuracy region.

Fabrication and Analysis of a Novel 3 DOF Parallel Wrist Mechanism

1995 ◽  
Vol 117 (2A) ◽  
pp. 343-345 ◽  
Author(s):  
S. K. Agrawal ◽  
Glen Desmier ◽  
Siyan Li
Keyword(s):  
Degrees Of Freedom ◽  
Kinematic Model ◽  
Ohio University ◽  
Three Degrees Of Freedom ◽  
Nominal Position

This paper describes a three-degrees-of-freedom parallel-actuated wrist mechanism developed at Ohio University. This mechanism is capable of pointing an axis within a cone from the nominal position. The mechanism allows unlimited rotation about the pointing axis. Experiments were conducted to validate the kinematic model of the designed wrist.

Kinematic model to control the end-effector of a continuum robot for multi-axis processing

Robotica ◽  
2015 ◽  
Vol 35 (1) ◽  
pp. 224-240 ◽  
Author(s):  
Salvador Cobos-Guzman ◽  
David Palmer ◽  
Dragos Axinte
Keyword(s):  
Degrees Of Freedom ◽  
Kinematic Model ◽  
Euler Angle ◽  
Inverse Kinematic ◽  
End Effector ◽  
Six Degrees Of Freedom ◽  
Hazardous Environments ◽  
Continuum Robot ◽  
Novel Method ◽  
Six Dof

SUMMARYThis paper presents a novel kinematic approach for controlling the end-effector of a continuum robot for in-situ repair/inspection in restricted and hazardous environments. Forward and inverse kinematic (IK) models have been developed to control the last segment of the continuum robot for performing multi-axis processing tasks using the last six Degrees of Freedom (DoF). The forward kinematics (FK) is proposed using a combination of Euler angle representation and homogeneous matrices. Due to the redundancy of the system, different constraints are proposed to solve the IK for different cases; therefore, the IK model is solved for bending and direction angles between (−π/2 to +π/2) radians. In addition, a novel method to calculate the Jacobian matrix is proposed for this type of hyper-redundant kinematics. The error between the results calculated using the proposed Jacobian algorithm and using the partial derivative equations of the FK map (with respect to linear and angular velocity) is evaluated. The error between the two models is found to be insignificant, thus, the Jacobian is validated as a method of calculating the IK for six DoF.

Design method of planar three-degrees-of-freedom serial compliance device with desired compliance characteristics

2012 ◽  
Vol 226 (9) ◽  
pp. 2331-2344 ◽  
Author(s):  
Man Bok Hong ◽  
Yong Je Choi
Keyword(s):  
Degrees Of Freedom ◽  
Design Method ◽  
Synthesis Method ◽  
Normal Contact ◽  
Compact Size ◽  
Novel Method ◽  
Parallel Connections ◽  
Mechanical Elements ◽  
Method Analysis ◽  
Three Degrees Of Freedom

In this article, a novel method for the systematic design of a planar three-degrees-of-freedom compliance device with desired compliance characteristics is presented. For the realization of desired compliance, the synthesis method of stiffness of a planar mechanism is first derived. The compliance device may be directly realized by means of parallel connections of the synthesized springs. However, the use of several mechanical elements such as joints and guides for spring assemblies for the realization may cause significant complexity in manufacturing the compliance device with high precision and in compact size. In order to resolve the problem, the form of serial connections of three torsional springs which has the same compliance as the form of parallel connections of the synthesized line springs is proposed. The serial form of torsional springs can be physically realized by designing proper shape of the circular flexure hinge corresponding to each of the torsional springs. For the illustration of the proposed design method, a planar serial compliance device with high compliance to the normal contact force is designed and verified by finite element method analysis.

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