Theory and Experiments on the Compliance Control of Redundant Robot Manipulators

1990 ◽  
Vol 112 (4) ◽  
pp. 653-660 ◽  
Author(s):  
H. Kazerooni ◽  
K. G. Bouklas ◽  
J. Guo
Keyword(s):  
Degrees Of Freedom ◽  
Control Method ◽  
Robot Manipulators ◽  
Industrial Robot ◽  
Redundant Robot ◽  
Control Approach ◽  
Six Degrees Of Freedom ◽  
The Stability ◽  
Control Methodology ◽  
Theory And Experiments

This work presents a control methodology for compliant motion in redundant robot manipulators. This control approach takes advantage of the redundancy in the robot’s degrees of freedom: while a maximum six degrees of freedom of the robot control the robot’s endpoint position, the remaining degrees of freedom impose an appropriate force on the environment. To verify the applicability of this control method, an active end-effector is mounted on an industrial robot to generate redundancy in the degrees of freedom. A set of experiments are described to demonstrate the use of this control method in constrained maneuvers. The stability of the robot and the environment is analyzed.

An Extended Jacobian-Based Formulation for Operational Space Control of Kinematically Redundant Robot Manipulators With Multiple Subtask Objectives: An Adaptive Control Approach

2019 ◽  
Vol 141 (5) ◽  
Author(s):  
Kamil Cetin ◽  
Enver Tatlicioglu ◽  
Erkan Zergeroglu
Keyword(s):  
Stability Analysis ◽  
Tracking Control ◽  
Robot Manipulators ◽  
Robot Dynamics ◽  
Simulation Studies ◽  
Matrix Formulation ◽  
Redundant Robot ◽  
Control Approach ◽  
Operational Space ◽  
The Stability

In this study, an extended Jacobian matrix formulation is proposed for the operational space tracking control of kinematically redundant robot manipulators with multiple subtask objectives. Furthermore, to compensate the structured uncertainties related to the robot dynamics, an adaptive operational space controller is designed, and then, the corresponding stability analysis is presented for kinematically redundant robot manipulators. Specifically, the proposed method is concerned with not only the stability of operational space objective but also the stability of multiple subtask objectives. The combined stability analysis of the operational space objective and the subtask objectives are obtained via Lyapunov based arguments. Experimental and simulation studies are presented to illustrate the performance of the proposed method.

An Adaptive Evolutionary Switching Control for Robot Manipulators

2005 ◽  
Author(s):  
P. R. Ouyang ◽  
W. J. Zhang ◽  
Madan M. Gupta
Keyword(s):  
Trajectory Tracking ◽  
Control Method ◽  
Robot Manipulators ◽  
Industrial Robot ◽  
Switching Control ◽  
Learning Ability ◽  
Pd Control ◽  
Control Approach ◽  
Gain Switching ◽  
Control Scheme

In this paper, a new adaptive switching control approach, called adaptive evolutionary switching PD control (AES-PD), is proposed for iterative operations of robot manipulators. The proposed AES-PD control method is a combination of the feedback of PD control with gain switching and feedforward using the input torque profile obtained from the previous iteration. The asymptotic convergence of the AES-PD control method is theoretically proved using Lyapunov’s method. The philosophy of the switching control strategy is interpreted in the context of the iteration domain to increase the speed of the convergence for trajectory tracking of robot manipulators. The AES-PD control has a simple control structure that makes it easily implemented. The validity of the proposed control scheme is demonstrated for the trajectory tracking of robot manipulators through simulation studies. Simulation results show that the AES-PD control can improve the tracking performance with an increase of the iteration number. The EAS-PD control method has the adaptive and learning ability; therefore, it should be very attractive to applications of industrial robot control.

High Bandwidth Motion Control for Multi-Axis Servohydraulic Mechanisms

2007 ◽  
Author(s):  
A. R. Plummer
Keyword(s):  
Motion Control ◽  
Degrees Of Freedom ◽  
Control Method ◽  
Earthquake Simulation ◽  
Control Approach ◽  
Six Degrees Of Freedom ◽  
Modes Of Vibration ◽  
High Bandwidth ◽  
Rigid Mass ◽  
Acceleration Tracking

A practical motion control method is presented for multiaxis parallel servohydraulic mechanisms in which the payload behaves as a rigid mass. The ability of this method to decouple the control axes is demonstrated. A modal control approach is used – i.e. the modes of vibration of the system are controlled individually. These modes are dependent on the inertial properties of the payload and the compliance of the actuators due to oil compressibility. For each mode, a partial non-linear dynamic inversion is performed in the control loop. To avoid the need to differentiate the position feedback signals, accelerometers are also used, and three-element motion state vectors are estimated using composite filtering. Command feedforward is used to increase the tracking bandwidth, and the closed-loop part of the controller can be conceived as a model-based disturbance observer. Simulation results are presented based on a detailed validated model of a large vibration table used for earthquake simulation. Just three of the six degrees-of-freedom of the table are considered, and the results for horizontal acceleration tracking response are presented, along with the ability of the controller to reject the ‘overturning moment’.

Balancing Control of a Mobile Manipulator with Two Wheels by an Acceleration-Based Disturbance Observer

2018 ◽  
Vol 15 (03) ◽  
pp. 1850005 ◽  
Author(s):  
Yeong-Geol Bae ◽  
Seul Jung
Keyword(s):  
Disturbance Observer ◽  
Degrees Of Freedom ◽  
Control Method ◽  
Experimental Studies ◽  
Service Robot ◽  
Mobile Manipulator ◽  
Control Performance ◽  
Six Degrees Of Freedom ◽  
Inertia Model ◽  
Balancing Control

This paper presents the balancing control performance of a mobile manipulator built in the laboratory as a service robot called Korean robot worker (KOBOKER). The robot is designed and implemented with two wheels as a mobile base and two arms with six degrees-of-freedom each. Kinematics and dynamics of the robot are analyzed. For the balancing control performance, two wheels are controlled independently by the time-delayed control method based on the inertia model of the robot. The acceleration information obtained directly from the sensor is used for the modified disturbance observer structure called an acceleration-based disturbance observer (AbDOB). Experimental studies of the balancing control of the robot are conducted to compare the control performances by both a PID control method and an AbDOB.

scholarly journals Neural Network Self-Tuning Control for a Piezoelectric Actuator

Sensors ◽  
2020 ◽  
Vol 20 (12) ◽  
pp. 3342 ◽  
Author(s):  
Wenjun Li ◽  
Chen Zhang ◽  
Wei Gao ◽  
Miaolei Zhou
Keyword(s):  
Neural Network ◽  
Control Method ◽  
Input Voltage ◽  
Rate Dependency ◽  
Output Displacement ◽  
Control Approach ◽  
Adaptive Parameter ◽  
Hysteresis Nonlinearity ◽  
Self Tuning ◽  
Control Methodology

Piezoelectric actuators (PEA) have been widely used in the ultra-precision manufacturing fields. However, the hysteresis nonlinearity between the input voltage and the output displacement, which possesses the properties of rate dependency and multivalued mapping, seriously impedes the positioning accuracy of the PEA. This paper investigates a control methodology without the hysteresis model for PEA actuated nanopositioning systems, in which the inherent drawback generated by the hysteresis nonlinearity aggregates the control accuracy of the PEA. To address this problem, a neural network self-tuning control approach is proposed to realize the high accuracy tracking with respect to the system uncertainties and hysteresis nonlinearity of the PEA. First, the PEA is described as a nonlinear equation with two variables, which are unknown. Then, using the capabilities of super approximation and adaptive parameter adjustment, the neural network identifiers are used to approximate the two unknown variables automatically updated without any off-line identification, respectively. To verify the validity and effectiveness of the proposed control methodology, a series of experiments is executed on a commercial PEA product. The experimental results illustrate that the established neural network self-tuning control method is efficient in damping the hysteresis nonlinearity and enhancing the trajectory tracking property.

Application of non-linear H∞ control to the Tetrabot robot manipulator

1998 ◽  
Vol 212 (6) ◽  
pp. 459-465 ◽  
Author(s):  
I Postlethwaite ◽  
A Bartoszewicz
Keyword(s):  
Degrees Of Freedom ◽  
Robot Manipulator ◽  
Industrial Robot ◽  
External Disturbances ◽  
Six Degrees Of Freedom ◽  
Control Scheme ◽  
Non Linear ◽  
Modelling Uncertainties ◽  
Real Robot ◽  
Robotic Application

In this paper, an application of a non-linear H∞ control law for an industrial robot manipulator is presented. Control of the manipulator motion is formulated into a non-linear H∞ optimization problem, namely optimal tracking performance in the presence of modelling uncertainties and external disturbances. Analytical solutions for this problem are implemented on a real robot. The robot under consideration is the six-degrees-of-freedom GEC Tetrabot. Investigations are made into the selection of weights for the H∞ controller and it is shown how different selections of weights affect the Tetrabot performance. The authors believe this to be the first robotic application of nonlinear H∞ control. Comparisons of the proposed control strategy with conventional proportional-derivative and proportional-integral-derivative controllers show favourable performance of the Tetrabot under the new non-linear H∞ control scheme.

Model Tests of a Caisson in Wet Towing for Assessing Resistance and Stability in Calm Water and Waves

2018 ◽  
Vol 140 (5) ◽  
Author(s):  
Chang-Wook Park ◽  
Jeonghwa Seo ◽  
Shin Hyung Rhee
Keyword(s):  
Degrees Of Freedom ◽  
Model Tests ◽  
Added Resistance ◽  
Power Requirement ◽  
Effective Power ◽  
Six Degrees Of Freedom ◽  
Calm Water ◽  
Improved Stability ◽  
Scale Ratio ◽  
The Stability

A series of model tests of a caisson in wet towing were conducted in a towing tank to assess the stability and effective power requirement in calm water and head sea conditions. The scale ratio of the model was 1/30, and the model-length-based Froude number in the tests ranged from 0.061 to 0.122, which is equivalent to 2 and 4 knots in the full scale, respectively. During the towing of the model, tension on the towline and six-degrees-of-freedom (6DOF) motion of the model were measured. Under the calm water condition, the effects of towing speed, draft, and initial trim variation on the towing stability and effective power were investigated. Initial trim improved stability and reduced required towing power. In head seas, effective power and towing stability were changed with the wavelength. It increased as the wavelength became longer, but the added resistance in long waves also stabilized the model with reduced yaw motion.

scholarly journals Crack Assessment of Wheel Hubs via an Ultrasonic Transducer and Industrial Robot

Sensors ◽  
2018 ◽  
Vol 18 (12) ◽  
pp. 4336 ◽  
Author(s):  
Hanming Zhang ◽  
Chunguang Xu ◽  
Dingguo Xiao
Keyword(s):  
Crack Growth ◽  
Ultrasonic Testing ◽  
Degrees Of Freedom ◽  
Industrial Robot ◽  
Ultrasonic Transducer ◽  
Robot Assisted ◽  
Six Degrees Of Freedom ◽  
Crack Location ◽  
Critical Areas ◽  
Growth Assessment

Crack assessment when making fitness-for-service decisions requires a thorough examination of crack location and size in critical areas. An ultrasonic transducer is used for such assessments, but traditional methods cannot cope with complex rotators, such as wheel hubs. We present a model of robot-assisted crack growth assessment in wheel hubs. We integrate a six-degrees-of-freedom (DOF) industrial robot and a turntable to form a robot-assisted ultrasonic testing (UT) system that does not use traditional UT equipment. Ultrasonic beams are focused at certain depths appropriate for achieving maximum sensitivity. We quantitatively analysed wheel hubs with longitudinal and transverse series of pre-cracks, and concluded that our system autonomously detected cracks.

Research on the Cornering Characteristics of Three-Axle Vehicle

2014 ◽  
Vol 945-949 ◽  
pp. 567-570
Author(s):  
Bo Xu ◽  
Sheng Min Cui ◽  
Xiang Yu Wu
Keyword(s):  
Degrees Of Freedom ◽  
Control Method ◽  
Front Wheel ◽  
Heavy Vehicle ◽  
Sideslip Angle ◽  
Motion Equations ◽  
Dynamic Steering ◽  
Angular Scale ◽  
Control Target ◽  
The Stability

A multi-axle dynamic steering technology was proposed to solve the steering stability and maneuverability problem of heavy vehicle. Two degrees of freedom linear steering-model and motion-equations of three-axle vehicle was established. Taking the zero sideslip angle as the control target and the proportional rear-front wheel angle as control method, we got the angular scale-factor equation and related matrix of the state space and transfer function. The MATLAB software was used to simulate the different steering modes stability steady-state and transient response. The results show that by using proportional control method the sideslip angle can be stabilized near zero and by using multi-axle dynamic steering technology the stability and maneuverability of the vehicle when steering can be improved effectively.

Position Control of Direct-Drive Robot Manipulators with PMAC Motors Using Enhanced Fuzzy PD Control

2004 ◽  
Vol 8 (3) ◽  
pp. 324-331
Author(s):  
Dong Sun ◽  
◽  
Y. X. Su ◽  
James K. Mills ◽  
Keyword(s):  
Position Control ◽  
Robot Manipulators ◽  
Pd Controller ◽  
Control Performance ◽  
Direct Drive ◽  
Control Approach ◽  
Single Link ◽  
Nonlinear Tracking ◽  
Control Methodology ◽  
Fuzzy Pd

A position control approach for direct-drive robot manipulators with permanent magnet AC (PMAC) motors is proposed. The conventional vector control architecture has been simplified by specifying the motor stator phase so that the rotating d-axis current is zero. The position control is designed to be an enhanced fuzzy PD controller, by incorporating two nonlinear tracking differentiators into a conventional fuzzy PD controller. The proposed control methodology is easy to implement, and exhibits better control performance than conventional control methods. Experiments conducted on a single-link manipulator directly driven by a PMAC motor demonstrate the validity of the proposed approach.

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