Control of grasp stiffness using a multifingered robot hand with redundant joints

Robotica ◽  
1995 ◽  
Vol 13 (4) ◽  
pp. 351-362 ◽  
Author(s):  
H. R. Choi ◽  
W. K. Chung ◽  
Y. Youm
Keyword(s):  
Control Method ◽  
Hierarchical Control ◽  
Joint Stiffness ◽  
Least Square ◽  
Robot Hand ◽  
Control Scheme ◽  
Least Square Problem ◽  
Stiffness Control ◽  
Planar Robot ◽  
The Stability

SummaryThis paper addresses a method of satisfactorily controlling the grasp of objects. Emphasis is placed on achieving the desired stiffness of a grasped object as accurately as possible, especially when the fingers have redundant joints. A model describing the relation between stiffness and force is derived. Based upon this model, a hierarchical control scheme of the grasp stiffness, called decentralized object stiffness control (DOSC) is proposed. DOSC is composed of a fingertip stiffness synthesis (FSS) algorithm and orthogonal stiffness decomposition control (OSDC). Employing the proposed FSS always achieves the desired grasp stiffness by solving the constrained least square problem. The computed fingertip stiffness is achieved by OSDC. It offers a feasible way of controlling the fingertip stiffness as well as maintaining the stability of the finger configuration by modulating the joint stiffness. The developed control method is implemented on a two-fingered planar robot hand one finger of which has a redundant joint. The effectiveness of the control method is confirmed experimentally.

scholarly journals An adaptive hierarchical control for aerial manipulators

Robotica ◽  
2018 ◽  
Vol 36 (10) ◽  
pp. 1527-1550 ◽  
Author(s):  
Francesco Pierri ◽  
Giuseppe Muscio ◽  
Fabrizio Caccavale
Keyword(s):  
Control Algorithm ◽  
Hierarchical Control ◽  
Bottom Layer ◽  
Trajectory Tracking Control ◽  
Aerial Manipulator ◽  
Control Scheme ◽  
Modelling Uncertainties ◽  
Aerial Vehicle ◽  
The Stability

SUMMARYThis paper addresses the trajectory tracking control problem for a quadrotor aerial vehicle, equipped with a robotic manipulator (aerial manipulator). The controller is organized in two layers: in the top layer, an inverse kinematics algorithm computes the motion references for the actuated variables; in the bottom layer, a motion control algorithm is in charge of tracking the motion references computed by the upper layer. To the purpose, a model-based control scheme is adopted, where modelling uncertainties are compensated through an adaptive term. The stability of the proposed scheme is proven by resorting to Lyapunov arguments. Finally, a simulation case study is proposed to prove the effectiveness of the approach.

scholarly journals A Theoretical Concept of Decoupled Current Control Scheme for Grid-Connected Inverter with L-C-L Filter

2021 ◽  
Vol 11 (14) ◽  
pp. 6256
Author(s):  
Mohamad Amin Ghasemi ◽  
Seyed Fariborz Zarei ◽  
Saeed Peyghami ◽  
Frede Blaabjerg
Keyword(s):  
Control Method ◽  
Controller Design ◽  
Current Control ◽  
System Stability ◽  
State Equations ◽  
Lcl Filter ◽  
Control Scheme ◽  
Grid Connected Inverter ◽  
The Stability ◽  
Grid Side

This paper proposes a nonlinear decoupled current control scheme for a grid-connected inverter with LCL filter. Decoupling the active and reactive current control channels is one of the main demands in the control of inverters. For inverters with an L filter, the decoupling can be achieved by a proper feed-forward of grid voltages. However, the coupling of channels is a complex issue for converters with LCL filters. The resonance mode of the LCL filter may cause instability, which adds more complexity to the analysis. In this paper, state equations of the system are provided, which highlight the coupling between active and reactive currents injected into the grid. Accordingly, a non-linear control scheme is proposed which effectively decouples the channels and dampens the resonant modes of the LCL filter. The stability of the proposed control method is verified by the Lyapunov criterion. Independency of the system stability to the grid-impedance is another feature of the proposed approach. Moreover, only grid-side currents are needed for implementation of the proposed scheme, avoiding the need for additional current sensors for the output capacitor and grid-side inductor. For accurate modelling of the inverter, the computation and PWM sampling delays are included in the controller design. Finally, various case studies are provided that verify the performance of the proposed approach and the stability of the system.

Task-space asymptotic tracking control of robots using a direct adaptive Taylor series controller

2018 ◽  
Vol 24 (23) ◽  
pp. 5570-5584 ◽  
Author(s):  
Seyed Mohammad Ahmadi ◽  
Mohammad Mehdi Fateh
Keyword(s):  
Taylor Series ◽  
Control Method ◽  
Tracking Error ◽  
Time Derivative ◽  
Approximation Error ◽  
Task Space ◽  
Control Approach ◽  
Control Scheme ◽  
Asymptotic Tracking ◽  
The Stability

This paper presents a robust task-space control approach using a direct adaptive Taylor series controller for electrically driven robot manipulators. In an adaptive Taylor series control scheme, the parameters of controller are directly tuned in order to reduce the task-space tracking error in the presence of structured and unstructured uncertainty. Also, the upper bound of approximation error is estimated to form a robustifying term and the asymptotic convergence of task-space tracking error and its time derivative is proven based on the stability analysis. Simulation results are included to verify the effectiveness of the proposed control method.

A Novel Trajectory Tracking Control Method for a Nonholonomic Mobile Robot with System Uncertainties and Disturbances

2013 ◽  
Vol 823 ◽  
pp. 193-198
Author(s):  
Run Zhou Zhao ◽  
Xi Zheng Zhang ◽  
Cai Hong Shi ◽  
Wei Chen
Keyword(s):  
Trajectory Tracking ◽  
Control Method ◽  
Hybrid Control ◽  
Kinematic Model ◽  
Network Dynamic ◽  
Trajectory Tracking Control ◽  
Dynamic Controller ◽  
Control Scheme ◽  
System Uncertainties ◽  
The Stability

This paper focuses on the trajectory tracking problem of mobile robots with system uncertainties and disturbances. With the integration of a kinematic controller and a dynamic controller, a hybrid control method is presented. Firstly, an adaptive kinematic controller is proposed through the kinematic model and backstepping method. Secondly, a neural network dynamic controller is proposed, with the consideration of system uncertainties and disturbances. The stability of the proposed control scheme is verified via the Lyapunov method and Barbalat lemma. Finally, results of circular trajectory simulation have illustrated the effectiveness of the present control scheme.

Inter-Trial Dynamics of Repeated Skilled Movements

2007 ◽  
Author(s):  
Joby John ◽  
Joseph P. Cusumano
Keyword(s):  
Hierarchical Control ◽  
Goal Function ◽  
Human Movements ◽  
Control Scheme ◽  
Goal Level ◽  
Goal Equivalent Manifold ◽  
Goal Functions ◽  
The Stability ◽  
Passive Sensitivity ◽  
Definition Of

In this paper, we develop a class of discrete dynamical systems for modeling repeated, goal-directed, kinematically redundant human movements. The approach is based on a mathematical definition of movement tasks in terms of goal functions. Each goal function can give rise to an associated goal equivalent manifold (GEM), which contains all body states that exactly satisfy the task requirements. A hierarchical control scheme involving in-trial action templates and inter-trial stochastic optimal error correction is included to generate a nonlinear map for the repeated execution of the task. A simple throwing task is used to illustrate the underlying concepts and to develop a model problem for further study. The performance at the goal level, as measured by the root mean square error, is shown to result from factors that are measures of passive sensitivity, the magnitude of body fluctuations, the orientation of fluctuations with the GEM, and the stability properties of the inter-trial controller. The action of the inter-trial controller developed for our model system is simulated and is shown to agree with the mathematically predicted performance.

scholarly journals A new approach on the modelling, chaos control and synchronization of a fractional biological oscillator

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Ali Saleh Alshomrani ◽  
Malik Zaka Ullah ◽  
Dumitru Baleanu
Keyword(s):  
Chaos Control ◽  
Control Method ◽  
Phase Portraits ◽  
New Approach ◽  
Control Scheme ◽  
Biological Oscillator ◽  
The Stability ◽  
Control And Synchronization ◽  
And Control ◽  
Active Control Method

AbstractThis research aims to discuss and control the chaotic behaviour of an autonomous fractional biological oscillator. Indeed, the concept of fractional calculus is used to include memory in the modelling formulation. In addition, we take into account a new auxiliary parameter in order to keep away from dimensional mismatching. Further, we explore the chaotic attractors of the considered model through its corresponding phase-portraits. Additionally, the stability and equilibrium point of the system are studied and investigated. Next, we design a feedback control scheme for the purpose of chaos control and stabilization. Afterwards, we introduce an efficient active control method to achieve synchronization between two chaotic fractional biological oscillators. The efficiency of the proposed stabilizing and synchronizing controllers is verified via theoretical analysis as well as simulations and numerical experiments.

Impactless Biped Walking on Stairs

2013 ◽  
Author(s):  
Lulu Gong
Keyword(s):  
Control Method ◽  
Effective Control ◽  
Ground Reaction Forces ◽  
Biped Walking ◽  
Control Scheme ◽  
Reaction Forces ◽  
Consumption Energy ◽  
Ground Reactions ◽  
The Stability ◽  
Energetic Performance

A motion/force control scheme was proposed to investigate biped impactless walking, which has proven to be used effectively to achieve stable walking on slopes. This paper aims to investigate the efficiency of walking stairs. Good trajectory generation and effective control method are important for operating and ensuring the stability of biped walking on stairs. Walking is illustrated by a seven-link biped with six control actuators, the number of which always equals to that of motion and force specifications. In order to avoid impacts, the specified motion of the biped and its ground reactions are controlled. Control torques, ground reaction forces and consumption energy of the biped lower limb joints are calculated for ascending stairs, walking on flat terrain and descending stairs. Three different locomotion velocities are studied in order to compare the energetic performance of the biped walking up-and-down stairs.

scholarly journals Study on spacecraft formation capture control method based on disturbance observer

2021 ◽  
Vol 39 (5) ◽  
pp. 1012-1021
Author(s):  
Xiaolong WANG ◽  
Chong SUN ◽  
Qun FANG ◽  
Qi LI ◽  
Shuo SONG
Keyword(s):  
Collision Avoidance ◽  
Disturbance Observer ◽  
Control Method ◽  
Avoidance Performance ◽  
Capture Process ◽  
Spacecraft Formation ◽  
Control Scheme ◽  
Close Range ◽  
The Stability ◽  
Compound Disturbance

In the presence of compound disturbances, a multi-spacecraft cooperative collision avoidance capture control method based on disturbance observer was proposed, which can solve the problem of low speed rolling non-cooperative target close-range capture in space. Firstly, a relative motion model of attitude and orbit coupling is established. Secondly, the disturbance observer is used to estimate and cancel the compound disturbance in the capture process. At the same time, the hyperquadric surfaces are used to describe the shape of space non-cooperative targets and capture spacecraft to establish a composite artificial potential field, and a robust control law with collision avoidance function is also designed. Finally, the stability of the controlled system is proved by using Lyapunov function, and the collision avoidance performance of the system is analyzed. Numerical simulations are carried out to evaluate the effectiveness of the proposed control scheme.

Stability Analysis of the Golden Section Adaptive Control Systems for Attitude Keeping of Spacecraft with Unknown Parameters

2011 ◽  
Vol 80-81 ◽  
pp. 1096-1102 ◽  
Author(s):  
Duo Qing Sun
Keyword(s):  
Adaptive Control ◽  
Control Method ◽  
Direct Method ◽  
Golden Section ◽  
Discrete Systems ◽  
Unknown Parameters ◽  
Adaptive Control Systems ◽  
Control Scheme ◽  
System Equations ◽  
The Stability

All-coefficient golden section adaptive control scheme for attitude keeping of spacecraft with unknown parameters is proposed in this paper. Based on Lyapunov’s direct method for time-variant discrete systems, the paper gives the conditions for the uniform asymptotic stability of the all-coefficient golden section adaptive control system. The given conditions are dependent on the relations between coefficients in the closed-loop system equations and the variable rates of the coefficients. The result in this paper can be used to analyze quantitatively the stability of multivariable time-variant discrete systems. Thus, a theoretical foundation is established to apply the golden section adaptive control method to control specific spacecraft.

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