Adaptive Computed Reference Computed Torque Control of Flexible Robots

1995 ◽  
Vol 117 (1) ◽  
pp. 31-36 ◽  
Author(s):  
I. M. M. Lammerts ◽  
F. E. Veldpaus ◽  
M. J. G. Van de Molengraft ◽  
J. J. Kok
Keyword(s):  
Degrees Of Freedom ◽  
Torque Control ◽  
Control Technique ◽  
Control Law ◽  
State Variables ◽  
Flexible Robots ◽  
Computed Torque Control ◽  
Link Flexibility ◽  
Simulation Results ◽  
Computed Torque

This paper presents a motion control technique for flexible robots and manipulators. It takes into account both joint and link flexibility and can be applied in adaptive form if robot parameters are unknown. It solves the main problems that are related to the fact that the number of degrees of freedom exceeds both the number of actuators and the number of output variables. The proposed method results in trajectory tracking while all state variables remain bounded. Global, asymptotic stability is ensured for all values of the stiffnesses of joints and links. To show the characteristics of the proposed control law, some simulation results are presented.

The Real-Time Control of Space Robot by Computed Torque Control Law

2011 ◽  
Vol 225-226 ◽  
pp. 978-981
Author(s):  
Bing Shao ◽  
En Tao Yuan ◽  
Zhong Hai Yu
Keyword(s):  
Real Time ◽  
Lie Groups ◽  
Lie Algebras ◽  
Torque Control ◽  
Space Robot ◽  
Control Law ◽  
Real Time Control ◽  
Time Control ◽  
Computed Torque Control ◽  
Computed Torque

Lie groups and Lie algebras are used to research the dynamics and computed torque law control of free flying space robot systems. First the adjoint transformations and adjoint operators of Lie groups and Lie algebras are discussed. Then the free flying base systems are transformed to fixed base systems. The inverse dynamics and forward dynamics are described with Lie groups and Lie algebras. The computed torque control law is used to simulate with the results of dynamics. The simulation results show that with the method the dynamical simulation problems of space robot can be solved quickly and efficiently. This built the foundation of real-time control based on dynamics. The computed torque control law has good performance.

Robust Framework for the Computed Torque Control of Nondeterministic Multibody Dynamic Systems

2016 ◽  
Author(s):  
Sahand Sabet ◽  
Mohammad Poursina
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Method ◽  
Feedback Linearization ◽  
Torque Control ◽  
Control Law ◽  
Mathematical Framework ◽  
Computed Torque Control ◽  
Highly Nonlinear ◽  
Multibody Problems ◽  
Computed Torque

Considering uncertainty is inarguably a crucial aspect of dynamic analysis, design, and control of a mechanical system. When it comes to multibody problems, the effect of uncertainty in the system’s parameters and excitations becomes even more significant due to the accumulation of inaccuracies. For this reason, this paper presents a detailed research on the use of the Polynomial Chaos Expansion (PCE) method for the control of nondeterministic multibody systems. PCE is essentially a way to compactly represent random variables. In this scheme, each stochastic response output and random input is projected onto the space of appropriate independent orthogonal polynomial basis functions. In the field of robotics, a required task is to force robotic arms to follow designated paths. Controlling such systems usually leads to difficulties since the dynamic equations of multibody problems are highly nonlinear. Computed Torque Control Law (CTCL) is able to overcome these difficulties by using feedback linearization to evaluate the required torque/force at any time to make the system follow a trajectory. In this paper, a mathematical framework is introduced to apply the Computed Torque Control Law to a multibody system with uncertainty. Surprisingly, it is shown that using this control scheme, uncertainty in geometry does not affect the closed-loop equations of controlled systems. Both the intrusive PCE method and the Monte Carlo approach are used to control a fully actuated two-link planar elbow arm where each link is required to follow a specified path. Lastly, a comparison of the time efficiency and accuracy between the traditionally used Monte Carlo method and the intrusive PCE is presented. The results indicate that the intrusive PCE approach can provide better accuracy with much less computation time than the Monte Carlo method.

scholarly journals Control par calculado para seguimiento de trayectoria aplicado a la dinámica de un robot de 3gdl con propósitos didácticos

2020 ◽  
pp. 1-8
Author(s):  
Juan Carlos Hernández-Durón ◽  
José Luis Ortiz-Simón ◽  
Martha Aguilera-Hernandez ◽  
Daniel Olivares-Caballero
Keyword(s):  
Dynamic Model ◽  
Degrees Of Freedom ◽  
Torque Control ◽  
Work Place ◽  
A Value ◽  
Computed Torque Control ◽  
Christoffel Symbols ◽  
Gravitational Vector ◽  
Three Degrees Of Freedom ◽  
Computed Torque

The article shows the needed procedure to obtain the dynamic model of a robot, with the purpose of being able to follow a planned path using the control law “CTC” Computed Torque Control. The robot was designed in a simple way for didactic reasons, this robot has three degrees of freedom, four links and three joints to move around in the work place. Two out of these joints are rotatory joints meanwhile the third one is a prismatic joint. The dynamic model of the robot is obtained using the Jacobians and Christoffel symbols of the center of mas of each link. Also including the Gravitational vector and the frictions of each joint. The objective of the dynamic model is to be able to simulate the robot in “Simulink” and test different paths using the computed torque control in which the gains of the control will be manipulated until a value that satisfies the desired path is found

Servo-Constraint Based Computed Torque Control of Underactuated Mechanical Systems

2011 ◽  
Author(s):  
La´szlo´ L. Kova´cs ◽  
Jo´zsef Ko¨vecses ◽  
Ambrus Zelei ◽  
La´szlo´ Bencsik ◽  
Ga´bor Ste´pan
Keyword(s):  
Degrees Of Freedom ◽  
Control Method ◽  
Equations Of Motion ◽  
Geometric Constraints ◽  
Torque Control ◽  
Underactuated Mechanical Systems ◽  
Computed Torque Control ◽  
Distribution Matrix ◽  
Underactuated Robot ◽  
Computed Torque

This paper aims to generalize the computed torque control method for underactuated systems which are modeled by a non-minimum set of generalized coordinates subjected to geometric constraints. The control task of the underactuated robot is defined in the form of servo constraint equations that have the same number as the number of independent control inputs. A PD controller is synthesized based on projecting the equations of motion into the nullspace of the distribution matrix of the actuator forces/torques. The results are demonstrated by numerical simulation and experiments conducted on a two degrees-of-freedom device.

scholarly journals The nonlinear computed torque control of a quadrotor

2020 ◽  
Vol 20 (3) ◽  
pp. 1221
Author(s):  
Y. Meddahi ◽  
K. Zemalache Meguenni ◽  
H. Aoued
Keyword(s):  
Torque Control ◽  
Kinematics And Dynamics ◽  
Dynamics Modeling ◽  
Quadrotor Helicopter ◽  
Computed Torque Control ◽  
Paper Work ◽  
Simulation Results ◽  
Computed Torque

<p>This paper work focused on the study of the nonlinear computed torque<br />control of a quadrotor helicopter. In order to model the dynamic of the<br />vehicles, kinematics and dynamics modeling of the X4 is presented. Euler<br />angles and parameters are used in the formulation of this model and the<br />technique of Computed Torque control is introduced. In the second part of<br />the paper, we develop a methodology of control that allows the quadrotor to<br />accomplish a prospecting mission of an environment, as the follow-up of a<br />trajectory by the simulation. Results show that Computed Torque control<br />method is suitable for X4.</p>

scholarly journals PD-computed torque control for an autonomous airship

2019 ◽  
Vol 8 (1) ◽  
pp. 44
Author(s):  
Y. Meddahi ◽  
K. Zemalache Meguenni
Keyword(s):  
Control Method ◽  
Torque Control ◽  
Kinematics And Dynamics ◽  
Control Law ◽  
Euler Angles ◽  
Dynamics Modeling ◽  
Computed Torque Control ◽  
Trajectory Following ◽  
Computed Torque

For the trajectory following problem of an airship, the standard computed torque control law is shown to be robust with respect to unknown dynamics by judiciously choosing the feedback gains and the estimates of the nonlinear dynamics. In the first part of this paper, kinematics and dynamics modeling of the airships is presented. Euler angles and parameters are used in the formulation of this model and the technique of Computed Torque control is introduced. In the second part of the paper, we develop a methodology of control that allows the airship to accomplish a prospecting mission of an environment, as the follow-up of a trajectory by the simulation who results show that Computed Torque control method is suitable for airships.

Computed Torque Control Method for Under-Actuated Manipulator

2009 ◽  
Author(s):  
Ambrus Zelei ◽  
La´szlo´ L. Kova´cs ◽  
Ga´bor Ste´pa´n
Keyword(s):  
Control Method ◽  
Differential Algebraic Equations ◽  
Torque Control ◽  
Pd Controller ◽  
Algebraic Equations ◽  
Ducted Fan ◽  
Computed Torque Control ◽  
Simulation Results ◽  
Load Angle ◽  
Computed Torque

The paper presents the dynamic analysis of a crane-like manipulator system equipped with complementary cables and ducted fan actuators. The investigated under-actuated mechanical system is described by a system of differential-algebraic equations. The position/orientation control problem is investigated with respect to the trajectory generation and the fine positioning of the payload. The closed form results include the desired actuator forces as well as the nominal load angle corresponding to the desired motion of the payload. Considering a PD controller, numerical simulation results and also experiments demonstrate the applicability of the concept of using complementary actuators for controlling the swinging motion of the payload.

Computed Torque Control of a Two-DOF Cable-Suspended Parallel Mechanism

2016 ◽  
Author(s):  
Zexiao Xie ◽  
Ben Ma ◽  
Ping Ren
Keyword(s):  
Parallel Mechanism ◽  
Degrees Of Freedom ◽  
Sufficient Conditions ◽  
Torque Control ◽  
Parallel Mechanisms ◽  
Computationally Efficient ◽  
Computed Torque Control ◽  
Point Motion ◽  
Point To Point ◽  
Computed Torque

This paper presents the design of a computed torque controller for a two-degree-of-freedom (two-dof) cable-suspended parallel mechanism. Unlike fully constrained cable-driven parallel mechanisms, cable-suspended parallel mechanisms are not redundantly actuated and usually have the same number of actuated cables as the degrees of freedom. Compared with rigid-link parallel mechanisms, the control of cabled parallel mechanisms is more challenging in that the cable tensions are unidirectional. Taking the input constraints into account, the method of computed torque control is applied to the two-dof planar cable robot. The sufficient conditions and necessary & sufficient conditions of the controller’s parameters are obtained, under which the positiveness of the tensions is always maintained during the point-to-point motion within the cable robot’s static workspace. Numerical simulations show that the controller is computationally efficient and the end-effector of the robot could converge to desired final positions with exponential stability.

scholarly journals Backlash Control via Redundant Drives: An Experimental Verification

1992 ◽  
Author(s):  
Lung-Wen Tsai ◽  
Sun-Lai Chang
Keyword(s):  
Pid Controller ◽  
Torque Control ◽  
The Other ◽  
Control Technique ◽  
Proof Of Concept ◽  
Computed Torque Control ◽  
Order Of Magnitude ◽  
Novel Concept ◽  
Gear Meshes ◽  
Computed Torque

Abstract In this paper, a novel concept for the control of backlash in geared servo-mechanisms is demonstrated with a prototype manipulator. The concept utilizes unidirectional redundant drives to assure positive coupling of gear meshes at all times and, thereby, eliminates backlash completely. To establish a proof of concept, a two-DOF prototype manipulator with three unidirectional drives is designed and tested. Dynamic model based on Lagrange’s formulation is established. A PID controller using computed torque control technique is developed. Two experiments, one with redundant drives and the other without redundant drives, are conducted. The experimental results demonstrate that use of unidirectional redundant drives improves the repeatability of a manipulator by an order of magnitude.

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