Command Generation Technique Research Articles

A novel command generation paradigm for production machine systems

Abstract This paper presents a new command generation technique titled VEPRO for computer controlled production machinery. In this method, the tool trajectory is described by a high-level scripting language that enables parametric representations of complex work-piece geometries. The interpreted script is then employed to generate the interpolation data required to compute a tool trajectory that is subjected to a number of kinematic constraints. A real-time interpolator is employed to provide the position commands required by each motion controller in a synchronous fashion. As a proof of concept, the proposed method is emulated on a PC using Python scripting language. The performance of the paradigm is rigorously assessed via two test cases involving different manufacturing techniques (e.g. pocket milling and 3D printing). Through the experimental results, the paper illustrates that the technique, which lends itself for real-time hardware implementation, exhibits satisfactory performance for all intensive purposes and that the method is technically feasible for a wide spectrum of manufacturing applications and systems.

High angle of attack command generation technique and tracking control for agile missiles

This paper proposes a new tracking control design for agile missiles at high angle of attack regime. Firstly, mathematical descriptions of the problem are presented, taking aerodynamic uncertainties into consideration. Based on the dynamics inverse modeling in a neural network (NN) architecture, the angle of attack command augmented by a variable structure technique is then generated to correspond with the desired turn rate. Subsequently, a nonlinear adaptive control approach using sliding mode control (SMC) technique is employed to track the angle of attack command. Due to the introduction of extended state observer (ESO), the proposed approach is able to online estimate the system uncertainties and calculate derivatives of signals required for composing the control law. Finally, to demonstrate the feasibility and validity of the proposed methodology, the numerical simulation of the agile missile intercepting a target in the rear hemisphere is presented.

Direct command generation for CNC machinery based on data compression techniques

This paper presents a direct command generation technique for digital motion control systems. In this paradigm, higher-order differences of a given trajectory (i.e. position) are calculated and the resulting sequence is compacted via data compression techniques. The overall method is capable of generating trajectory data at variable rates in forward- and reverse-directions with the utilization of a linear interpolator. As a part of the command generation scheme, the paper also proposes a new data compression technique titled @DY10. Apart from this new method, the performances of the proposed generator employing different compression algorithms (such as Huffman coding, Arithmetic coding, LZW, and run length encoding) are also evaluated through three test cases. The paper illustrates that the @DY10 technique, which is suitable for real-time hardware implementation, exhibits satisfactory performance in terms of data compaction achieved in the test cases considered.

Command Generation Techniques for a Pin Array using the SVD and the SNMF

This paper presents two command generation techniques for improving the surface generation time of a pin array device, specifically a prototype called Digital Clay. The procedures use singular value decomposition (SVD) and semi-nonnegative matrix factorization (SNMF) to create intermediate surfaces that sum to a desired surface. Although the focus is on pin array control, the techniques can apply to any system with a set of subsystems coupled by the row-column input method. The row-column method allows multiple actuators to be controlled by a few inputs. Current procedures for systems using the row-column method are too slow for many applications. Recent work has improved the time response of these systems using simultaneous feedback control but can potentially create unwanted oscillatory behavior. This paper describes command generation techniques using the SVD and SNMF that maintain the improvement in time without the oscillations. Simulation results compare the two procedures to the line scanning technique used in previous work on pin arrays.

Control of Tower Cranes With Double-Pendulum Payload Dynamics

The usefulness of cranes is limited because the payload is supported by an overhead suspension cable that allows oscillation to occur during crane motion. Under certain conditions, the payload dynamics may introduce an additional oscillatory mode that creates a double pendulum. This paper presents an analysis of this effect on tower cranes. This paper also reviews a command generation technique to suppress the oscillatory dynamics with robustness to frequency changes. Experimental results are presented to verify that the proposed method can improve the ability of crane operators to drive a double-pendulum tower crane. The performance improvements occurred during both local and teleoperated control.

AN INTERNET-DRIVEN TOWER CRANE FOR DYNAMICS AND CONTROLS EDUCATION

An advanced controls class taught at both the Georgia Institute of Technology and the Tokyo Institute of Technology focuses on command generation, remote manipulation, and human interaction with control systems. To aid in teaching these concepts, a portable tower crane was constructed. The tower crane can follow pre-programmed trajectories or be driven manually. It can also be operated from anywhere in the world with an internet connection. The crane can perform both feedback and command shaping anti-swing control while measuring trolley position and payload swing. The system enables students to perform a variety of useful and interesting laboratories and student projects. The students participated in and studied the effects of remote operator behavior, non-linear system dynamics, and advanced command generation techniques. The paper describes the tower crane and the results of this new educational endeavor.

Use of Input Shaping to Decrease the Effects of Stiction

Stiction can be a major detriment to the performance of machines that move at low velocities or attempt to position with high accuracy. The control of machines with stiction is further complicated if the machine has flexible dynamics that lead to vibration and transient deflection. Command generation schemes have recently been shown to eliminate many of the problems associated with flexible dynamics. This paper investigates the use of command generation techniques for reducing the effects of stiction, as well as vibration. It is shown that command generation allows the positioning feedback gains to be increased, thereby reducing the positioning error associated with stiction, without increasing vibration.

On-Off Control With Specified Fuel Usage

A method for generating on-off command profiles for flexible systems is presented. The command profiles move a system without residual vibration while using a specified amount of actuator fuel. Robustness to modeling errors can be incorporated into the design of the command signals. Techniques are presented that facilitate implementation and indicate prudent choices for the amount of fuel to be used. The method is compared to other command generation techniques that balance fuel usage and slew time.

Suboptimal command generation for control moment gyroscopes and feedback control of spacecraft

This paper presents a suboptimal gimbal-angle command generation technique and a Lyapunov-based tracking control law for control moment gyroscopes. The formulation of the open-loop maneuver problem exploits the principle of conservation of angular momentum. This allows for a reduction in the dimensionality of the problem— only the kinematics need be considered. The gimbal rates are parametrized as polynomial functions of time, and the parameters are optimized. The objective function of the optimization is the singularity measure. The optimal null motion used is determined after computing the open-loop gimbal-rate profiles. A feedback strategy is used to track the open-loop reference attitude and angular velocity profiles. Null motion is also used to allow the closedloop gimbal angles to follow the open-loop gimbal-angle histories. This procedure avoids neighboring singularities and also provides repeatability. Simulation results are presented for rest-to-rest maneuvers using a model of a ground-based test article. The results show that a wide domain of singularity-free operation around the reference solution can be provided with this approach.

A flexible command generation technique for application in dialogue systems

AbstractAn important problem in the design of image processing systems is the specification of appropriate command structures for control of dedicated hardware and software functions. This paper describes a general and flexible method for the definition and processing of specialized commands. The idea is to generalize the specification of parameters within procedures by allowing—in a well‐controlled way—a few syntactic extensions. The paper presents the extension mechanism, demonstrates the power of the command processor by practical examples and discusses some critical points.