Analysis and control of redundant manipulator dynamics based on an extended operational space

Robotica ◽  
2001 ◽  
Vol 19 (6) ◽  
pp. 649-662 ◽  
Author(s):  
Ki Cheol Park ◽  
Pyung-Hun Chang ◽  
Sukhan Lee
Keyword(s):  
Null Space ◽  
Performance Measure ◽  
The Self ◽  
Real Time Control ◽  
End Effector ◽  
Time Control ◽  
Operational Space ◽  
Minimum Number ◽  
And Control ◽  
Self Motion

In this paper a new concept, named the Extended Operational Space (EXOS), has been proposed for the effective analysis and the real-time control of the robot manipulators with kinematic redundancy. The EXOS consists of the operational space (OS) and the optimal null space (NS): the operational space is used to describe manipulator end-effector motion; whereas the optimal null space, described by the minimum number of NS vectors, is used to express the self motion.Based upon the EXOS formulation, the kinematics, statics, and dynamics of redundant manipulators have been analyzed, and control laws based on the dynamics have been proposed. The inclusion of only the minimum number of NS vectors has changed the resulting dynamic equations into a very compact form, yet comprehensive enough to describe: not only the dynamic behavior or the end effector, but also that of the self motion; and at the same time the interaction of these two motions. The comprehensiveness is highlighted by the demonstration of the dynamic couplings between OS dynamics and NS dynamics, which are quite elusive in other approaches.Using the proposed dynamic controls, one can optimize a performance measure while tracking a desired end-effector trajectory with a better computational efficiency than the conventional methods. The effectiveness of the proposed method has been demonstrated by simulations and experiments.

scholarly journals A singularity handling algorithm based on operational space control for six-degree-of-freedom anthropomorphic manipulators

2019 ◽  
Vol 16 (3) ◽  
pp. 172988141985891
Author(s):  
Zhi-Hao Kang ◽  
Ching-An Cheng ◽  
Han-Pang Huang
Keyword(s):  
Null Space ◽  
Singularity Analysis ◽  
Degree Of Freedom ◽  
Control Input ◽  
Real Time Control ◽  
Time Control ◽  
Operational Space ◽  
Industrial Manipulators ◽  
Space Motion ◽  
Six Degree Of Freedom

In this article, we analyze the singularities of six-degree-of-freedom anthropomorphic manipulators and design a singularity handling algorithm that can smoothly go through singular regions. We show that the boundary singularity and the internal singularity points of six-degree-of-freedom anthropomorphic manipulators can be identified through a singularity analysis, although they do not possess the nice kinematic decoupling property as six-degree-of-freedom industrial manipulators. Based on this discovery, our algorithm adopts a switching strategy to handle these two cases. For boundary singularities, the algorithm modifies the control input to fold the manipulator back from the singular straight posture. For internal singularities, the algorithm controls the manipulator with null space motion. We show that this strategy allows a manipulator to move within singular regions and back to non-singular regions, so the usable workspace is increased compared with conventional approaches. The proposed algorithm is validated in simulations and real-time control experiments.

Redundancy Parameterization for Flexible Motion Control

2010 ◽  
Author(s):  
B. Moore ◽  
E. Oztop
Keyword(s):  
Finite Number ◽  
Inverse Kinematics ◽  
Infinitely Many Solutions ◽  
Redundant Manipulators ◽  
Real Time Control ◽  
End Effector ◽  
Human Control ◽  
Time Control ◽  
Swivel Angle ◽  
Self Motion

Our overall research interest is in synthesizing human like reaching and grasping using anthropomorphic robot hand-arm systems, as well as understanding the principles underlying human control of these actions. When one needs to define the control and task requirements in the Cartesian space, the problem of inverse kinematics needs to be solved. For non-redundant manipulators, a desired end-effector position and orientation can be achieved by a finite number of solutions. For redundant manipulators however, there are in general infinitely many solutions where the cardinality of the solution set must be made finite by imposing certain constraints. In this paper, we consider the Mitsubishi PA10 manipulator which is similar to the human arm, in the sense that both wrist and shoulder joints can be considered to emulate a 3DOF ball joint. We explicitly derive the analytic solution for the inverse kinematics using quaternions. Then, we derive a parameterization in terms of a pure quaternion called the swivel quaternion. The swivel quaternion is similar to the elbow swivel angle used in most approaches, but avoid the computation of inverse trigonometric functions. This parameterization of the self-motion manifold is continuous with any end-effector motion. Given the pose of the end-effector and the swivel quaternion (or swivel angle), the algorithm derives all solution of the inverse kinematics (finite number). We then show how the parameterization of the elbow self-motion can be used for the real-time control of the PA10 manipulator in the presence of obstacles.

Self-Motion Utilization for Reducing Vibration of a Structurally Flexible Redundant Robot Manipulator System

1997 ◽  
Author(s):  
Seon-Jae Kim ◽  
Youn-Sik Park
Keyword(s):  
Null Space ◽  
Robot Manipulator ◽  
The Self ◽  
Body Motion ◽  
Inertia Force ◽  
Structural Flexibility ◽  
Redundant Manipulators ◽  
End Effector ◽  
Self Motion ◽  
Modal Space

Abstract This paper addresses the self-motion utilization of structurally flexible redundant manipulators to reduce the vibration of links when structural flexibility is present. Utilizing the self-motion capability, the motion-induced vibration can be further reduced by altering the joint trajectory during and after motion, while maintaining the end-effector tracing a given trajectory. That is because self-motion does not affect end-effector motion at all. In this proposed algorithm, a null space acceleration is evaluated in order to cancel the inertia force of flexural motion that is induced by its rigid body motion. A concept of modal space is applied to reduce the system degree of freedom. The dominant modal forces defined at a specific time, which are the same number of degree of redundancy can be effectively canceled out by employing self-motion. Through numerical simulation with three-link planar robotic manipulators, the effectiveness and applicability of the suggested method have been demonstrated.

Integrative Modeling Platform for Design and Control of an Adaptive Wind Turbine Blade

2018 ◽  
Author(s):  
Hamid Khakpour Nejadkhaki ◽  
John F. Hall ◽  
Minghui Zheng ◽  
Teng Wu
Keyword(s):  
Simulation Model ◽  
Wind Turbine ◽  
Real Time ◽  
Turbine Blade ◽  
Design Tool ◽  
Real Time Control ◽  
Time Control ◽  
Partial Load ◽  
And Control

A platform for the engineering design, performance, and control of an adaptive wind turbine blade is presented. This environment includes a simulation model, integrative design tool, and control framework. The authors are currently developing a novel blade with an adaptive twist angle distribution (TAD). The TAD influences the aerodynamic loads and thus, system dynamics. The modeling platform facilitates the use of an integrative design tool that establishes the TAD in relation to wind speed. The outcome of this design enables the transformation of the TAD during operation. Still, a robust control method is required to realize the benefits of the adaptive TAD. Moreover, simulation of the TAD is computationally expensive. It also requires a unique approach for both partial and full-load operation. A framework is currently being developed to relate the TAD to the wind turbine and its components. Understanding the relationship between the TAD and the dynamic system is crucial in the establishment of real-time control. This capability is necessary to improve wind capture and reduce system loads. In the current state of development, the platform is capable of maximizing wind capture during partial-load operation. However, the control tasks related to Region 3 and load mitigation are more complex. Our framework will require high-fidelity modeling and reduced-order models that support real-time control. The paper outlines the components of this framework that is being developed. The proposed platform will facilitate expansion and the use of these required modeling techniques. A case study of a 20 kW system is presented based upon the partial-load operation. The study demonstrates how the platform is used to design and control the blade. A low-dimensional aerodynamic model characterizes the blade performance. This interacts with the simulation model to predict the power production. The design tool establishes actuator locations and stiffness properties required for the blade shape to achieve a range of TAD configurations. A supervisory control model is implemented and used to demonstrate how the simulation model blade performs in the case study.

Dynamic modeling, system identification and comparative study of various control strategies for a spatial parallel manipulator

2021 ◽  
pp. 095965182110320
Author(s):  
Mervin Joe Thomas ◽  
Shoby George ◽  
Deepak Sreedharan ◽  
ML Joy ◽  
AP Sudheer
Keyword(s):  
Real Time ◽  
Parallel Manipulator ◽  
Control Strategies ◽  
Proportional Integral Derivative ◽  
Real Time Control ◽  
Model Predictive Controller ◽  
End Effector ◽  
Proportional Integral ◽  
Time Control ◽  
Predictive Controller

The significant challenges seen with the mathematical modeling and control of spatial parallel manipulators are its difficulty in the kinematic formulation and the inability to real-time control. The analytical approaches for the determination of the kinematic solutions are computationally expensive. This is due to the passive joints, solvability issues with non-linear equations, and inherent kinematic constraints within the manipulator architecture. Therefore, this article concentrates on an artificial neural network–based system identification approach to resolve the complexities of mathematical formulations. Moreover, the low computation time with neural networks adds up to its advantage of real-time control. Besides, this article compares the performance of a constant gain proportional–integral–derivative (PID), variable gain proportional–integral–derivative, model predictive controller, and a cascade controller with combined variable proportional–integral–derivative and model predictive controller for real-time tracking of the end-effector. The control strategies are simulated on the Simulink model of a 6-degree-of-freedom 3-PPSS (P—prismatic; S—spherical) parallel manipulator. The simulation and real-time experiments performed on the fabricated manipulator prototype indicate that the proposed cascade controller with position and velocity compensation is an appropriate method for accurate tracking along the desired path. Also, training the network using the experimentally generated data set incorporates the mechanical joint approximations and link deformities present in the fabricated model into the predicted results. In addition, this article showcases the application of Euler–Lagrangian formalism on the 3-PPSS parallel manipulator for its dynamic model incorporating the system constraints. The Lagrangian multipliers include the influence of the constraint forces acting on the manipulator platform. For completeness, the analytical model results have been verified using ADAMS for a pre-defined end-effector trajectory.

Design and Development of a Multi-Module Deployable Manipulator

1999 ◽  
Author(s):  
Kenneth Wong ◽  
Vinod J. Modi ◽  
Clarence W. de Silva ◽  
Arun K. Misra
Keyword(s):  
Real Time ◽  
Experimental Investigations ◽  
Computationally Efficient ◽  
Real Time Control ◽  
Design And Development ◽  
Time Control ◽  
Dynamics And Control ◽  
Manipulator Design ◽  
A Chain ◽  
And Control

Abstract This paper presents the design and development of a Multi-module Deployable Manipulator System (MDMS) as well as a dynamical formulation for it. The system is designed for experimental investigations aimed at dynamics and control of this variable geometry manipulator by implementing different control algorithms to regulate its performance. The manipulator operates in a horizontal plane and is unique in that it comprises of four modules, each of which has one revolute joint and one prismatic joint, connected in a chain topology. Each module has a slewing link of approximately 20cm length and is capable of extending by 15cm. The manipulator design involves the selection and sizing of actuators, the design of mounting and connecting components, and the selection of hardware as well as software for real-time control. The dynamical model is formulated using an O(N) algorithm, based on the Lagrangian approach and velocity transformations. The O(N) character is computationally efficient permitting real-time control of the system.

Modeling, Model Reduction, and Control of a Hands-Free Two-Wheeled Self-Balancing Scooter

2020 ◽  
pp. 185-202
Author(s):  
Qiong Li ◽  
Wangling Yu ◽  
H. Henry Zhang
Keyword(s):  
Model Reduction ◽  
Large Scale ◽  
Power Transmission ◽  
System Response ◽  
Real Time Control ◽  
Time Control ◽  
Iteration Period ◽  
Synergistic Approach ◽  
Model Reduction Technique ◽  
And Control

Designing a two-wheeled self-balancing scooter involves in the synergistic approach of multidisciplinary engineering fields with mutual relationships of power transmission, mass transmission, and information transmission. The scooter consists of several subsystems and forms a large-scale system. The mathematical models are in the complex algebraic and differential equations in the form of high dimension. The complexity of its controller renders difficulties in its realization due to the limit of iteration period of real time control. Routh model reduction technique is employed to convert the original high-dimensional mathematical model into a simplified lower dimensional form. The modeling is derived using a unified variational method for both mechanical and electrical subsystems of the scooter, and for the electronic components equivalent circuit method is adopted. Simulations of the system response are based on the reduced model and its control design. A prototype is developed and realized with Matlab-Labview simulation and control environment.

scholarly journals Teleoperation Control Design with Virtual Force Feedback for the Cable-Driven Hyper-Redundant Continuum Manipulator

2020 ◽  
Vol 10 (22) ◽  
pp. 8031
Author(s):  
Long Qin ◽  
Fanghao Huang ◽  
Zheng Chen ◽  
Wei Song ◽  
Shiqiang Zhu
Keyword(s):  
Force Feedback ◽  
Inverse Kinematic ◽  
Real Time Control ◽  
Kinematics Model ◽  
Time Control ◽  
Virtual Force ◽  
Control Scheme ◽  
Continuum Manipulators ◽  
Transmission Structure ◽  
And Control

Hyper-redundant continuum manipulators present dexterous kinematic skills in complicated tasks and demonstrate promising potential in underground exploration, intra-cavity inspection, surgery, etc. However, the hyper-redundancy, which endows much dexterity and flexibility, brings a huge challenge to the kinematics solution and control of the continuum manipulators. Due to the pseudoinverse calculation of high-order Jacobian matrix or iteration, many inverse kinematic solution approaches of continuum manipulators are very time-consuming, which extremely limit their applicability in real-time control. Additionally, it is often difficult for the manipulators to perform the tasks well in complex scenarios due to lack of human intervention. Therefore, in this paper, a simplified kinematics model of a typical hyper-redundant manipulator is proposed based on its unique geometry relationships, where the mapping relationships between the actuators’ rotation and the end-effector’s position are derived through the analysis of its driving subsystem and motion subsystem, in particular the joint modules. To perform the tasks of manipulators with the help of operators, a teleoperation control scheme with modified wave transmission structure is designed to achieve the guaranteed stability and improved transparency, and the leader’s trajectory and generated force feedback are the transmitted signals in the communication channel. Specifically, a virtual force feedback generation algorithm is developed in the teleoperation control scheme via the processing tracking errors, which can improve the operators’ assistance and perception during the teleoperation process. The practical experiments with comparative wave variable structures in two different sets are implemented to verify the effectiveness of proposed kinematics model and control scheme.

Real time control for reduced aeration and chemical consumption: a full scale study

2010 ◽  
Vol 61 (9) ◽  
pp. 2169-2175 ◽  
Author(s):  
A. Thornton ◽  
N. Sunner ◽  
M. Haeck
Keyword(s):  
Activated Sludge ◽  
Real Time ◽  
Full Scale ◽  
Real Time Control ◽  
Effluent Quality ◽  
Time Control ◽  
Whole Plant ◽  
Running Cost ◽  
The Uk ◽  
And Control

The use of the activated sludge process (ASP) for the nitrification/denitrification of wastewaters is commonplace throughout the UK and many other parts of the industrial world. Associated with this process are significant costs arising from aeration requirements and for selected sites, the need to provide an external carbon source. These costs can constitute up to of 50% of the total running cost of the whole plant and as such, any effort to reduce them could realise significant benefits. This paper investigates the use of real time control (RTC) using online sensors and control algorithms to optimise the operation of the ASP, leading to greater efficiency and sustainability. Trials were undertaken at full scale to assess the benefit of such a system at a 250,000 population equivalent (PE) works on the south coast of the UK, using Activated sludge model No.1 (ASM 1) as a basis for the control system. Initial results indicate that it is possible to significantly reduce both aeration and chemical consumption costs whilst still delivering the required effluent quality. Over the trial period the aeration requirements were consistently reduced by 20% whereas, a reduction in methanol consumption of in excess of 50% was observed.

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