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.

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.

Teaching Real-Time Control Using Arduino: Timer ISR vs delayMicroseconds

2017 ◽  
Author(s):  
Ryan W. Krauss
Keyword(s):  
Control Systems ◽  
Real Time ◽  
Initial Assessment ◽  
Control Law ◽  
Assessment Data ◽  
Real Time Control ◽  
Simplified Approach ◽  
Time Control ◽  
Timing Function ◽  
Feedback Control Systems

Arduino microcontrollers are inexpensive and easy to program, making them very popular among hobbyists and “makers”. Arduinos are also surprisingly capable when it comes to creating real-time feedback control systems. This paper investigates several facets of using Arduino microcontrollers to teach students to create real-time control systems. A simplified approach to enforcing the real-time execution of a control law is introduced based on the delayMicroseconds function and its accuracy is compared to the standard timer interrupt approach. Initial assessment data is presented on whether or not the delayMicroseconds approach is easier for students to understand. The accuracy of the Arduino’s built-in timing function micros is also investigated.

scholarly journals Robotic Comanipulation With Active Impedance Control

2009 ◽  
Author(s):  
Rui Cortesa˜o ◽  
Brian Zenowich ◽  
Rui Arau´jo ◽  
William Townsend
Keyword(s):  
Impedance Control ◽  
Torque Control ◽  
Task Space ◽  
Control Techniques ◽  
Time Control ◽  
Computed Torque Control ◽  
Position Data ◽  
Active Impedance ◽  
Design Experiments ◽  
Computed Torque

The paper presents active impedance control for robotic comanipulation tasks, enabling virtual contact interactions. Computed torque control in the task space powered by multiple-output active observers (AOBs) is proposed, enhancing haptic perception. Forces and force derivatives are artificially measured from position data around an equilibrium point that can move with time. Control techniques to deal with critical impedances are introduced, taking into account the noise distribution along the system. Stochastic design is discussed. A dynamic model of the redundant lightweight 7-DOF WAM™ arm is derived and evaluated, playing a key role in the control design. Experiments for small and high impedances are presented, highlighting merits and limitations of the approach. A comparative study between active and non-active impedance control is made.

Optimal adaptive computed torque control for haptic-teleoperation system with uncertain dynamics

2021 ◽  
pp. 095965182110480
Author(s):  
Tayfun Abut ◽  
Servet Soyguder
Keyword(s):  
Real Time ◽  
Optimization Algorithm ◽  
Control Method ◽  
Torque Control ◽  
Gray Wolf ◽  
Uncertain Dynamics ◽  
Computed Torque Control ◽  
Dynamic Uncertainty ◽  
Control Coefficients ◽  
Computed Torque

This study aimed to eliminate dynamic uncertainty, one of the main problems of haptic teleoperation robotic systems. The optimal adaptive computed torque control method was used to overcome this problem. As is known, excellent stability and transparency are required in teleoperation systems. However, dynamic uncertainty that causes stability problems in the control of these systems also causes poor performance. In conventional adaptive computed torque control methods, updating the parameters of the system is generally discussed, but updating the control coefficients of vital importance in the control of the system is not considered. In the proposed method, an adaptation rule has been created to update uncertain parameters. In addition, the gray wolf optimization algorithm, one of the current optimization algorithms, has been proposed and applied to obtain the control coefficients of the system. The position tracking stability of the system was examined by using Lyapunov stability analysis method. As a result, both simulation and real-time optimal adaptive computational torque control method were used and bilateral position and force control was performed and the performance results of the system are obtained graphically and examined. Optimal adaptive computed torque control method obtained using the gray wolf optimization algorithm was used first in the literature search and success results have been obtained. In this regard, the authors have the idea that this work is an innovative aspect of both simulation and real time with the optimal adaptive computed torque control method.

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.

Real-Time Dynamic Control of a Stewart Platform

2013 ◽  
Vol 390 ◽  
pp. 398-402 ◽  
Author(s):  
Nicolas Andres Ordoñez ◽  
Carlos Francisco Rodríguez
Keyword(s):  
Real Time ◽  
Control Strategy ◽  
Virtual Work ◽  
Dynamic Control ◽  
Parallel Robots ◽  
Torque Control ◽  
Real Time Control ◽  
Time Dynamic ◽  
Time Control ◽  
Stewart Gough Platform

This paper presents a real-time control strategy for the parallel robots such as the Stewart-Gough platform. The strategy is implemented using xPC Target (a Matlab toolbox), achieving sample rates higher than 1 kHz for the control loop. A modified explicit dynamic model, based on the virtual work principle, allows the formulation of dynamic control schemes, commonly used to control serial manipulators. Based on this approach, a computed torque control with friction compensation is implemented for a Stewart-Gough platform. Experimental results are compared with a classic uncoupled control strategy.

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