Deformation Control of Elastic Object by Robot Arm - High-Precision Deformation Control by Adaptive Feed-forward Control -

1998 ◽  
Vol 10 (3) ◽  
pp. 184-190
Author(s):  
Hiroyuki Kojima ◽  
◽  
Masakazu Kamei ◽  
Tsuneo Akuto ◽  
Keyword(s):  
Least Squares Method ◽  
Feedforward Control ◽  
Equations Of Motion ◽  
Phase Error ◽  
Identification Algorithm ◽  
Robot Arm ◽  
Deformation Control ◽  
Feed Forward Control ◽  
Adaptive Feedforward ◽  
Elastic Object

This paper derives the equations of motion of a horizontal three-link robot arm contacting an elastic object, then proposes deformation control for the elastic object by the robot arm. This deformation control involves feedback control of joint angles, feedforward control by robot arm dynamics, and adaptive feedforward control for unknown elastic object dynamics. An adaptive feedforward control law is devised using an online parameter identification algorithm based on the least squares method, zero phase error tracking control theory, and the Jacobian matrix of the robot arm. Numerical simulation and experimental results confirmed that deformation control error by the proposed adaptive control rapidly decreases with the passing of time.

Tool Positioning for Noncircular Cutting With Lathe

1987 ◽  
Vol 109 (2) ◽  
pp. 176-179 ◽  
Author(s):  
M. Tomizuka ◽  
M. S. Chen ◽  
S. Renn ◽  
T. C. Tsao
Keyword(s):  
Cross Sections ◽  
Control Algorithm ◽  
Least Squares Method ◽  
Feedforward Control ◽  
Phase Error ◽  
Control Law ◽  
Time Model ◽  
Tool Positioning ◽  
Tool Position ◽  
Zero Phase

This paper presents the design and implementation of a digital controller for a lathe to machine workpieces with noncircular cross sections. Noncircular cutting is accomplished by controlling the radial tool position in the direction normal to the surface of workpiece. A discrete time model for the tool carriage in the radial direction is obtained by a least squares method applied to input and output data. The model is used for designing digital feedback and feedforward controllers. The zero phase error tracking control algorithm is applied as a feedforward control law for positioning of the tool along desired time varying signals. The effectiveness of the proposed controller is demonstrated by experiment and simulation.

High-Speed End Milling Using a Feedforward Control Architecture

1996 ◽  
Vol 118 (2) ◽  
pp. 178-187 ◽  
Author(s):  
E. D. Tung ◽  
M. Tomizuka ◽  
Y. Urushisaki
Keyword(s):  
High Speed ◽  
Feedforward Control ◽  
End Milling ◽  
Phase Error ◽  
Cutting Speed ◽  
Frequency Domain Analysis ◽  
Maximum Speed ◽  
Drive Control ◽  
Machining Errors ◽  
Feedforward Controller

Experiments are performed for end milling aluminum at 15,000 RPM spindle speed (1,508 m/min cutting speed) and up to 3 m/min table feedrate using an experimental machine tool control system. A digital feedforward controller for feed drive control incorporates the Zero Phase Error Tracking Controller (ZPETC) and feedforward friction compensation. The controller achieves near-perfect (±3 μm) tracking over a 26 mm trajectory with a maximum speed of 2 m/min. The maximum contouring error for a 26 mm diameter circle at this speed is less than 4 μm. Tracking and contouring experiments are conducted for table feedrates as high as 10 m/min. Frequency domain analysis demonstrates that the feedforward controller achieves a bandwidth of 10 Hz without phase distortion. In a direct comparison of accuracy, the machining errors in specimens produced by the experimental controller were up to 20 times smaller than the errors in specimens machined by an industrial CNC.

Trajectory Tracking of Underactuated Multibody Systems

2011 ◽  
Author(s):  
Stefan Reichl ◽  
Wolfgang Steiner
Keyword(s):  
Trajectory Tracking ◽  
Multibody Systems ◽  
Degrees Of Freedom ◽  
Inverse Dynamics ◽  
Feedforward Control ◽  
Equations Of Motion ◽  
Three Dimensional ◽  
Differential Algebraic Equations ◽  
State Variables ◽  
Algebraic Equations

This work presents three different approaches in inverse dynamics for the solution of trajectory tracking problems in underactuated multibody systems. Such systems are characterized by less control inputs than degrees of freedom. The first approach uses an extension of the equations of motion by geometric and control constraints. This results in index-five differential-algebraic equations. A projection method is used to reduce the systems index and the resulting equations are solved numerically. The second method is a flatness-based feedforward control design. Input and state variables can be parameterized by the flat outputs and their time derivatives up to a certain order. The third approach uses an optimal control algorithm which is based on the minimization of a cost functional including system outputs and desired trajectory. It has to be distinguished between direct and indirect methods. These specific methods are applied to an underactuated planar crane and a three-dimensional rotary crane.

Vibration Control of a Multi-Layer Piezoelectric Cylindrical Shell

1997 ◽  
Author(s):  
Jinhao Qiu ◽  
Junji Tani
Keyword(s):  
Cylindrical Shell ◽  
Feedforward Control ◽  
Equations Of Motion ◽  
Good Control ◽  
Expansion Method ◽  
Piezoelectric Sensor ◽  
State Equation ◽  
Integrated Sensor ◽  
Modal Expansion ◽  
Modal Expansion Method

Abstract Equations of motion for multi-layer piezoelectric cylindrical shells and the equations of the integrated piezoelectric sensors are derived. The state equation is obtained by solving the equations of motion with modal expansion method. The feedback control, feedforward control, and their combination are applied in the control of forced vibration of the piezoelectric cylindrical shell with integrated sensor and actuators. The simulation and experimental results show that good control effectiveness can be obtained by using the integrated piezoelectric sensor and actuators in conjunction with the combination of feedback and feedforward control methods.

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