On the Spatial Compliance of Robotic Manipulators

1997 ◽  
Vol 119 (4) ◽  
pp. 839-844 ◽  
Author(s):  
E. D. Fasse
Keyword(s):  
Spatial Reasoning ◽  
Impedance Control ◽  
Control Law ◽  
Spatial Transformation ◽  
Compliance Control ◽  
Interactive Control ◽  
Control Schemes ◽  
Stiffness Control ◽  
Geometrical Version ◽  
Spatial Compliance

Interactive control schemes, such as stiffness control and impedance control, are widely accepted as a means to actively accommodate environmental forces, but have not been widely applied. This is in part because well-known controllers are parametrized in a mathematically convenient, but nonintuitive way. “Spatial compliance control” is a Euclidean-geometrical version of compliance control that is parametrized in an intuitive way. A family of compliances is introduced with spatial transformation properties that simplify spatial reasoning aspects of compliance parameter selection. A control law is derived assuming that the robot consists of a serial linkage of rigid links actuated by variable-effort actuators.

scholarly journals Robust Synchronization of Delayed Chaotic FitzHugh-Nagumo Neurons under External Electrical Stimulation

2012 ◽  
Vol 2012 ◽  
pp. 1-11 ◽  
Author(s):  
Muhammad Rehan ◽  
Keum-Shik Hong
Keyword(s):  
Electrical Stimulation ◽  
Nonlinear Control ◽  
Control Law ◽  
Input Control ◽  
Control Schemes ◽  
Multiple Input ◽  
Cognitive Diseases ◽  
Single Input ◽  
Error Dynamics ◽  
Nonlinear Control Law

Synchronization of chaotic neurons under external electrical stimulation (EES) is studied in order to understand information processing in the brain and to improve the methodologies employed in the treatment of cognitive diseases. This paper investigates the dynamics of uncertain coupled chaotic delayed FitzHugh-Nagumo (FHN) neurons under EES for incorporated parametric variations. A global nonlinear control law for synchronization of delayed neurons with known parameters is developed. Based on local and global Lipschitz conditions, knowledge of the bounds on the neuronal states, the Lyapunov-Krasovskii functional, and theL2gain reduction, a less conservative local robust nonlinear control law is formulated to address the problem of robust asymptotic synchronization of delayed FHN neurons under parametric uncertainties. The proposed local control law guarantees both robust stability and robust performance and provides theL2bound for uncertainty rejection in the synchronization error dynamics. Separate conditions for single-input and multiple-input control schemes for synchronization of a wide class of FHN systems are provided. The results of the proposed techniques are verified through numerical simulations.

A Design Method of LS-SVM Based Stable Adaptive Controller for a Class of Nonlinear Systems

2011 ◽  
Vol 48-49 ◽  
pp. 17-20
Author(s):  
Chun Li Xie ◽  
Tao Zhang ◽  
Dan Dan Zhao ◽  
Cheng Shao
Keyword(s):  
Nonlinear Systems ◽  
Design Method ◽  
Nonlinear Function ◽  
Lyapunov Stability Theory ◽  
Adaptive Controller ◽  
Control Law ◽  
Continuous Systems ◽  
Control Schemes ◽  
Closed Systems ◽  
Simulation Results

A design method of LS-SVM based stable adaptive controller is proposed for a class of nonlinear continuous systems with unknown nonlinear function in this paper. Due to the fact that the control law is derived based on the Lyapunov stability theory, the scheme can not only solve the tracking problem of this class of nonlinear systems, but also it can guarantee the asymptotic stability of the closed systems, which is superior to many LS-SVM based control schemes. The effectiveness of the proposed scheme is demonstrated by simulation results.

scholarly journals Position Domain Synchronization Control For Robotic Manipulators

2021 ◽  
Author(s):  
Vangjel Pano
Keyword(s):  
Time Domain ◽  
Robotic Manipulators ◽  
Synchronization Control ◽  
Control Law ◽  
Control Input ◽  
Contour Tracking ◽  
Hybrid Controller ◽  
Reference Motion ◽  
Control Scheme ◽  
Control Schemes

Developed in this thesis is a new control law focusing on the improvement of contour tracking of robotic manipulators. The new control scheme is a hybrid controller based on position domain control (PDC) and position synchronization control (PSC). On PDC, the system’s dynamics are transformed from time domain to position domain via a one-to-one mapping and the position of the master axis motion is used as reference instead of time. The elimination of the reference motion from the control input improves contouring performance relative to time domain controllers. Conversely, PSC seeks to reduce the error of the systems by diminishing the synchronization error between each agent of the system. The new control law utilizes the aforementioned techniques to maximize the contour performance. The Lyapunov method was used to prove the proposed controller’s stability. The new control law was compared to existing control schemes via simulations of linear and nonlinear contours, and was shown to provide good tracking and contouring performances.

scholarly journals Research and Ground Verification of the Force Compliance Control Method for Space Station Manipulator

2020 ◽  
Vol 2020 ◽  
pp. 1-17
Author(s):  
Bingshan Hu ◽  
Huanlong Chen ◽  
Liangliang Han ◽  
Hongliu Yu
Keyword(s):  
Real Time ◽  
Contact Force ◽  
Control Algorithm ◽  
Control Method ◽  
Impedance Control ◽  
Space Station ◽  
Gravity Compensation ◽  
Compliance Control ◽  
Experiment Platform ◽  
Dual Arm

The space station manipulator does lots of tasks with contact force/torque on orbit. To ensure the safety of the space station and the manipulator, the contact force/torque of manipulator must be controlled. Based on analyzing typical tasks’ working flows and force control requirements, such as ORU (orbit replacement unit) changeout and dual arm collaborative payload transport, an impedance control method based on wrist 6 axis force/torque feedback is designed. For engineering implementation of the impedance control algorithm, the discretization method and impedance control parameters selection principle are also studied. To verify the compliance control algorithm, a ground experiment platform adopting industrial manipulators is developed. In order to eliminate the influence of gravity, a real-time gravity compensation algorithm is proposed. Then, the correctness of real-time gravity compensation and force compliance control algorithm is verified on the experiment platform. Finally, the ORU replacement and dual arm collaborative payload transport experiments are done. Experimental results show that the force compliance control method proposed in this paper can control the contact force and torque at the end of the manipulator when executing typical tasks.

Simultaneous Trajectory Tracking and Stiffness Control of Cable Actuated Parallel Manipulator

2009 ◽  
Author(s):  
Kun Yu ◽  
Leng-Feng Lee ◽  
Venkat N. Krovi
Keyword(s):  
Trajectory Tracking ◽  
Parallel Manipulators ◽  
Control Input ◽  
Robot System ◽  
Trajectory Tracking Control ◽  
Implementation Framework ◽  
Actuation Redundancy ◽  
Cable Robot ◽  
Control Schemes ◽  
Stiffness Control

Cable-actuated parallel manipulators combine benefits of large workspaces, significant payload capacities and high stiffness by virtue of the cable actuation. However, redundant/surplus cables are required to overcome the unidirectional nature of forces exertable by cables. This leads to actuation redundancy which needs to be resolved in order to realize some of the benefits. We study the implication of using actuation redundancy to tailor the workspace (task space) stiffness of the cable robot system. Suitable trajectory tracking control schemes are developed that additionally achieve secondary goal of active stiffness control to improve disturbance rejection, under positive control input constraint We demonstrate the performance of these control schemes using a point-mass cable robot system modeled within a virtual prototyping (VP) implementation framework.

Sliding Mode Impedance and Stiffness Control of a Pneumatic Cylinder

2019 ◽  
Author(s):  
Jonathon E. Slightam ◽  
Eric J. Barth ◽  
Mark L. Nagurka
Keyword(s):  
Motion Control ◽  
Sliding Mode ◽  
Impedance Control ◽  
Pneumatic Cylinder ◽  
Control Methods ◽  
Control Applications ◽  
Compliant Motion ◽  
Simultaneous Control ◽  
Stiffness Control ◽  
Virtual Impedance

Abstract Pneumatic double acting cylinders are able to provide inherent stiffness and force control for compliant motion control applications. Impedance control methods allow for a broad spectrum of mechanical properties of actuators to be achieved. The range of this spectrum can be increased by simultaneously controlling the actuator’s inherent stiffness and impedance, a concept explored in this paper. Presented here is a sliding mode impedance and stiffness controller for a servo-pneumatic double acting cylinder. Two proportional servo-valves are employed for simultaneous control of the virtual impedance and inherent stiffness of the pneumatic cylinder. Experimental results of tracking trajectories and contact are reported and discussed with respect to different approaches in the literature.

Iterative Learning Impedance Control in Gait Rehabilitation Robot

2014 ◽  
Vol 494-495 ◽  
pp. 1084-1087
Author(s):  
Fu Cheng Cao ◽  
Hai Xin Sun ◽  
Li Rong Wang
Keyword(s):  
Iterative Learning Control ◽  
Control Algorithm ◽  
Closed Loop ◽  
Impedance Control ◽  
Iterative Learning ◽  
Gait Rehabilitation ◽  
Control Law ◽  
Rehabilitation Robot ◽  
Simulation Results ◽  
Impedance Parameters

An iterative learning impedance control algorithm is presented to control a gait rehabilitation robot. According to the circumstances of the patient, the appropriate rehabilitation target impedance parameters are set. With the adoption of iterative learning control law, the impedance error in the closed loop is guaranteed to converge to zero and the iterative trajectories follow the desired trajectories over the entire operation interval. The effectiveness of the proposed method is shown through numerical simulation results.

Dynamic multi-priority control in redundant robotic systems

Robotica ◽  
2013 ◽  
Vol 31 (7) ◽  
pp. 1155-1167 ◽  
Author(s):  
Hamid Sadeghian ◽  
Luigi Villani ◽  
Mehdi Keshmiri ◽  
Bruno Siciliano
Keyword(s):  
Null Space ◽  
Impedance Control ◽  
Robotic Systems ◽  
Whole Body ◽  
Control Law ◽  
Level Control ◽  
Redundant Robots ◽  
Dynamic Level ◽  
The Stability ◽  
Robot Body

SUMMARYThis paper presents a dynamic-level control algorithm to meet simultaneously multiple desired tasks based on allocated priorities for redundant robotic systems. It is shown that this algorithm can be treated as a general framework to achieve control over the whole body of the robot. The control law is an extension of the well-known acceleration-based control to the redundant robots, and considers also possible interactions with the environment occurring at any point of the robot body. The stability of this algorithm is shown and some of the previously developed results are formulated using this approach. To handle the interaction on robot body, null space impedance control is developed within the multi-priority framework. The effectiveness of the proposed approaches is evaluated by means of computer simulation.

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