scholarly journals Aerial Tele-Manipulation with Passive Tool via Parallel Position/Force Control

2021 ◽  
Vol 11 (19) ◽  
pp. 8955
Author(s):  
Mostafa Mohammadi ◽  
Davide Bicego ◽  
Antonio Franchi ◽  
Davide Barcelli ◽  
Domenico Prattichizzo
Keyword(s):  
Contact Interaction ◽  
Force Control ◽  
Degrees Of Freedom ◽  
Haptic Feedback ◽  
Situational Awareness ◽  
Control Method ◽  
Bilateral Teleoperation ◽  
Compliant Structure ◽  
Rotational Degrees Of Freedom ◽  
Remote Sites

This paper addresses the problem of unilateral contact interaction by an under-actuated quadrotor UAV equipped with a passive tool in a bilateral teleoperation scheme. To solve the challenging control problem of force regulation in contact interaction while maintaining flight stability and keeping the contact, we use a parallel position/force control method, commensurate to the system dynamics and constraints in which using the compliant structure of the end-effector the rotational degrees of freedom are also utilized to attain a broader range of feasible forces. In a bilateral teleoperation framework, the proposed control method regulates the aerial manipulator position in free flight and the applied force in contact interaction. On the master side, the human operator is provided with force haptic feedback to enhance his/her situational awareness. The validity of the theory and efficacy of the solution are shown by experimental results. This control architecture, integrated with a suitable perception/localization pipeline, could be used to perform outdoor aerial teleoperation tasks in hazardous and/or remote sites of interest.

Haptic Feedback Applied to Pneumatic Walking

2008 ◽  
Author(s):  
Brian Guerriero ◽  
Wayne Book
Keyword(s):  
Force Control ◽  
Force Feedback ◽  
Haptic Feedback ◽  
Control Method ◽  
Position Tracking ◽  
Bilateral Teleoperation ◽  
Pneumatic Actuators ◽  
Position Controller ◽  
Pressure Feedback ◽  
Foot Position

This paper presents a proposed control method for controlling the foot positions of two robotic legs through direct operator inputs with haptic feedback. The robot consists of two 3-DoF legs driven by pneumatic actuators. A demonstration of the controller shows the tracking performance enhancements of the proposed force-based position controller over a simple differential pressure gain scheduler-based position controller. The proposed controller incorporates pressure feedback to create supplementary force control. Foot position tracking remains within 10% of the commanded reference position, even through the sharp disparities of loading conditions as the actuators are either lifting the weight of the legs or supporting the weight of the robot itself. An operator gives direct foot position commands to the controller through two PHANToM haptic devices. Bilateral teleoperation of the system provides directional force feedback to the operator as a function of foot position error. The proposed controller also decreases the ambient and false forces reflected to the operator while moving the legs through gait cycles.

scholarly journals Extending model-mediation method to multi-degree-of-freedom teleoperation systems experiencing time delays in communication

Robotica ◽  
2015 ◽  
Vol 35 (5) ◽  
pp. 1121-1136 ◽  
Author(s):  
Emre Uzunoğlu ◽  
Mehmet İsmet Can Dede
Keyword(s):  
Time Delays ◽  
Control Algorithm ◽  
Degrees Of Freedom ◽  
Control Method ◽  
Test Results ◽  
Bilateral Teleoperation ◽  
Extended Version ◽  
Teleoperation System ◽  
Teleoperation Systems ◽  
Three Degrees Of Freedom

SUMMARYIn this study, a bilateral teleoperation control algorithm is developed in which the model-mediation method is integrated with an impedance controller. The model-mediation method is also extended to three-degrees-of-freedom teleoperation. The aim of this controller is to compensate for instability issues and excessive forcing applied to the slave environment stemming from time delays in communication. The proposed control method is experimentally tested with two haptic desktop devices. Test results indicate that stability and passivity of the bilateral teleoperation system is preserved under variable time delays in communication. It is also observed that safer interactions of the slave system with its environment can be achieved by utilizing an extended version of the model-mediation method with an impedance controller.

FORCE CONTROL OF THE REDUNDANT LEG OF A BIPED ROBOT TO PRODUCE LARGE INERTIAL EFFECTS FOR CROSSING OBSTACLES

2012 ◽  
Vol 09 (01) ◽  
pp. 1250003 ◽  
Author(s):  
PAUL-FRANÇOIS DOUBLIEZ ◽  
OLIVIER BRUNEAU ◽  
FETHI BEN OUEZDOU
Keyword(s):  
Force Control ◽  
Degrees Of Freedom ◽  
Control Method ◽  
Biped Robot ◽  
Servo Control ◽  
Joint Torque ◽  
Singular Case ◽  
Obstacle Crossing ◽  
Dynamic Obstacle ◽  
Three Degrees Of Freedom

This paper proposes an energy control method for dynamic obstacle crossing by a planar biped. This approach was tested in a simulation where it was found to enable the biped robot to cross obstacles of different heights, due to inertial forces, by leaning with the front foot on the obstacles. The propulsion energy of the system is produced by the rear leg, which is endowed with four actuated degrees-of-freedom (hip, knee, ankle, toes), and is controlled by force control with four degrees-of-freedom in the non-singular case, and three degrees-of-freedom in the singular case. This paper identifies ten geometric, energetic and servo-control parameters necessary for dynamic obstacle crossing. The methodology presented allowed the dynamic crossing of an obstacle up to 20 cm high, at which point the joint torque limit for the propelling ankle was reached.

Bilateral teleoperation with continuously variable scaling and PD force control

2020 ◽  
pp. 014233121989592
Author(s):  
Burak Oztoprak ◽  
Eray A. Baran ◽  
Asif Sabanovic
Keyword(s):  
Real Time ◽  
Force Control ◽  
Control Method ◽  
Continuous Functions ◽  
Complete Analysis ◽  
Bilateral Teleoperation ◽  
Bilateral Control ◽  
Time Operation ◽  
Wide Range ◽  
Real Time Operation

This paper investigates the bilateral teleoperation with the possibility of continuously variable scaling during real-time operation. The algorithm proposed for this purpose provides the operator with the ability to change the scaling gains of force and velocity loops during operation. The controllers are derived to enforce exponentially decaying error dynamics on systems which have inner loop disturbance compensation. The proposed architecture assumes the scale factors as continuous functions of time which have continuous derivatives that are also included in the mathematical derivation. Unlike the existing studies, the presented framework allows real-time adaptation of scaling gains, which provides the user with the ability to conduct coarse and fine motion in the same operation. The Lyapunov stability proof of the proposed method is made and the margins of the controller gains are identified for practical operation. Furthermore, the operational accuracy is enhanced by the application of a PD force control loop which is also new for scaled bilateral teleoperation. The realization of PD loop is made using an [Formula: see text]-[Formula: see text]-[Formula: see text] filter to differentiate the force signal. The algorithm is validated on a setup consisted of two single DOF motion control systems. In order to provide a complete analysis, a wide range of experiments are made, velocity and force scales having sinusoidal patterns with different amplitudes and frequencies. Moreover, comparison with a classical bilateral control architecture is made to highlight the flexibility of the proposed control method. The efficacy of the proposed approach is solidified by the successful tracking responses obtained from these experiments.

Development of an Active Worktable and Its Application to Force Control of Robot Manipulators

2000 ◽  
Vol 12 (3) ◽  
pp. 249-253
Author(s):  
Shin-ichi Nakajima ◽  
Keyword(s):  
Force Control ◽  
Degrees Of Freedom ◽  
Control Method ◽  
Robot Manipulator ◽  
Impedance Control ◽  
Robot Manipulators ◽  
Compliant Motion ◽  
Stiffness Control

An active worktable, which can be applied to force control tasks of commercial robot manipulators, has been designed and built. The active worktable has several degrees of freedom and accommodates its position/force in accordance with the motion of a robot manipulator. A stiffness control method and an impedance control method are implemented in the active worktable to achieve compliant motion. Several experiments were carried out to confirm basic effectiveness of the active worktable.

scholarly journals Adaptive attitude tracking control of a 3-degrees-of-freedom experimental helicopter with actuator dead-zone

2018 ◽  
Vol 233 (1) ◽  
pp. 91-99 ◽  
Author(s):  
Chuang Li ◽  
Xuebo Yang ◽  
Bing Xiao
Keyword(s):  
Degrees Of Freedom ◽  
Control Method ◽  
Dead Zone ◽  
Adaptive Fuzzy Control ◽  
Lyapunov Stability Theory ◽  
Feedback Controllers ◽  
Attitude Tracking ◽  
Rotational Degrees Of Freedom ◽  
Theory State ◽  
Attitude Tracking Control

In this article, the attitude tracking problem of a three rotational degrees-of-freedom experimental helicopter is studied based on adaptive fuzzy control method. The system unmodeled dynamics, external disturbances, and actuator dead-zone fault are taken into consideration simultaneously. The uncertainties and the faults are compensated by resorting to the fuzzy logic system. Based on adaptive backstepping technique and Lyapunov stability theory, state feedback controllers are designed such that the reference signals can be tracked by the elevation and pitch angles, respectively, within small errors. Finally, experimental results are given to demonstrate the reliability of the proposed method.

On the Use of Quantum Thermal Bath in Unimolecular Fragmentation Simulations

2019 ◽  
Author(s):  
Riccardo Spezia ◽  
Hichem Dammak
Keyword(s):  
Degrees Of Freedom ◽  
Molecular Simulations ◽  
Zero Point ◽  
Thermal Bath ◽  
Unimolecular Dissociation ◽  
Point Energy ◽  
Rotational Degrees Of Freedom ◽  
The Difference ◽  
Nuclear Effects

<div> <div> <div> <p>In the present work we have investigated the possibility of using the Quantum Thermal Bath (QTB) method in molecular simulations of unimolecular dissociation processes. Notably, QTB is aimed in introducing quantum nuclear effects with a com- putational time which is basically the same as in newtonian simulations. At this end we have considered the model fragmentation of CH4 for which an analytical function is present in the literature. Moreover, based on the same model a microcanonical algorithm which monitor zero-point energy of products, and eventually modifies tra- jectories, was recently proposed. We have thus compared classical and quantum rate constant with these different models. QTB seems to correctly reproduce some quantum features, in particular the difference between classical and quantum activation energies, making it a promising method to study unimolecular fragmentation of much complex systems with molecular simulations. The role of QTB thermostat on rotational degrees of freedom is also analyzed and discussed. </p> </div> </div> </div>

scholarly journals A 4-DOF Upper Limb Exoskeleton for Physical Assistance: Design, Modeling, Control and Performance Evaluation

2021 ◽  
Vol 11 (13) ◽  
pp. 5865
Author(s):  
Muhammad Ahsan Gull ◽  
Mikkel Thoegersen ◽  
Stefan Hein Bengtson ◽  
Mostafa Mohammadi ◽  
Lotte N. S. Andreasen Struijk ◽  
...  
Keyword(s):  
Upper Limb ◽  
Tracking Control ◽  
Degrees Of Freedom ◽  
Control Method ◽  
Mechanical Design ◽  
Trajectory Tracking Control ◽  
Upper Limb Exoskeleton ◽  
And Performance ◽  
Physically Disabled People ◽  
Human Upper Limb

Wheelchair mounted upper limb exoskeletons offer an alternative way to support disabled individuals in their activities of daily living (ADL). Key challenges in exoskeleton technology include innovative mechanical design and implementation of a control method that can assure a safe and comfortable interaction between the human upper limb and exoskeleton. In this article, we present a mechanical design of a four degrees of freedom (DOF) wheelchair mounted upper limb exoskeleton. The design takes advantage of non-backdrivable mechanism that can hold the output position without energy consumption and provide assistance to the completely paralyzed users. Moreover, a PD-based trajectory tracking control is implemented to enhance the performance of human exoskeleton system for two different tasks. Preliminary results are provided to show the effectiveness and reliability of using the proposed design for physically disabled people.

scholarly journals Torque Ripple Suppression of PMSM Based on Robust Two Degrees-of-Freedom Resonant Controller

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1015
Author(s):  
Mingfei Huang ◽  
Yongting Deng ◽  
Hongwen Li ◽  
Jing Liu ◽  
Meng Shao ◽  
...  
Keyword(s):  
Control Strategy ◽  
Measurement Errors ◽  
Degrees Of Freedom ◽  
Control Method ◽  
Torque Ripple ◽  
Current Loop ◽  
Two Degrees Of Freedom ◽  
Robust Stability Analysis ◽  
Resonant Controller ◽  
Testing Environments

This paper concentrates on a robust resonant control strategy of a permanent magnet synchronous motor (PMSM) for electric drivers with model uncertainties and external disturbances to improve the control performance of the current loop. Firstly, to reduce the torque ripple of PMSM, the resonant controller with fractional order (FO) calculus is introduced. Then, a robust two degrees-of-freedom (Robust-TDOF) control strategy was designed based on the modified resonant controller. Finally, by combining the two control methods, this study proposes an enhanced Robust-TDOF regulation method, named as the robust two degrees-of-freedom resonant controller (Robust-TDOFR), to guarantee the robustness of model uncertainty and to further improve the performance with minimized periodic torque ripples. Meanwhile, a tuning method was constructed followed by stability and robust stability analysis. Furthermore, the proposed Robust-TDOFR control method was applied in the current loop of a PMSM to suppress the periodic current harmonics caused by non-ideal factors of inverter and current measurement errors. Finally, simulations and experiments were performed to validate our control strategy. The simulation and experimental results showed that the THDs (total harmonic distortion) of phase current decreased to a level of 0.69% and 5.79% in the two testing environments.

Effect of Rotational Degrees of Freedom on Molecular Mobility

2013 ◽  
Vol 117 (13) ◽  
pp. 6800-6806 ◽  
Author(s):  
M. Jafary-Zadeh ◽  
C. D. Reddy ◽  
Yong-Wei Zhang
Keyword(s):  
Molecular Mobility ◽  
Degrees Of Freedom ◽  
Rotational Degrees Of Freedom
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