Sensorless torque estimation in multidegree-of-freedom flexible systems

This paper presents a sensorless torque estimation algorithm for multidegree-of-freedom flexible systems. The proposed algorithm makes it possible to estimate externally applied torques due to flexible system s interaction with the environment without taking any measurement from the system. The algorithm is based on modifying the disturbance observer in order to decouple the reflected torque waves out of the total disturbance on the actuator. Then Reflected torque waves are used along with the actuator s current and velocity to estimate flexible system parameters, dynamics and the external torques or disturbances. Several experimental results are included in order to confirm the validity of the proposed torque estimation algorithm

Sensorless action-reaction-based residual vibration suppression for multi-degree-of-freedom flexible systems

This paper demonstrates the feasibility of controlling motion and vibration of a class of flexible systems with inaccessible or unknown outputs through measurements taken from their actuators which are used as single platforms for measurements, whereas flexible dynamical systems are kept free from any attached sensors. Based on the action reaction law of dynamics, the well-known disturbance observer is used to determine the incident reaction forces from these dynamical systems on the interface planes with their actuators. Reaction forces are considered as feedback-like signals that can be used as alternatives to the inaccessible system outputs. The sensorless action reaction based motion and vibration control technique is implemented on a flexible system with finite modes and all results are verified experimentally

Sensorless torque/force control

Motion control systems represent a main subsystem for majority of processing systems that can be found in the industrial sector. These systems are concerned with the actuation of all devices in the manufacturing process such as machines, robots, conveyor systems and pick and place mechanisms such that they satisfy certain motion requirements, e.g., the pre specified reference trajectories are followed along with delivering the proper force or torque to the point of interest at which the process occurs. In general, the aim of force/torque control is to impose the desired force on the environment even if the environment has dynamical motion

A novel algorithm for sensorless motion control, parameter identication and position estimation

This article demonstrates that an actuator can be used as a single platform for measurement, control and estimation by designing a chain of estimators and performing simple off-line experiments. Making use of the fact that rejected torque from the dynamical system consists of all the system dynamics beside all external disturbances. The rejected torque waves are estimated using the actuator parameters, and used for an off-line experiment for parameter estimation, then the estimated rejected torque is used along with the estimated parameters to estimate the positions of any multi-degree of freedom flexible dynamical system. That makes it possible to use those estimates to achieve sensorless motion and vibration control without using actual measurement. Moreover, all the estimated parameters and system dynamics can be used in order to estimate any external disturbance on the system when it starts to interact with the environment

Force Estimation for Teleoperating Industrial Robots

As the energy on the particle accelerators or heavy ion accelerators such as CERN or GSI, fusion reactors such as JET or ITER, or other scientific experiments is increased, it is becoming increasingly necessary to use remote handling techniques in order to interact with the remote and radioactive environment

Optimal motion control and vibration suppression of flexible systems with inaccessible outputs

This work addresses the optimal control problem of dynamical systems with inaccessible outputs. A case in which dynamical system outputs cannot be measured or inaccessible. This contradicts with the nature of the optimal controllers which can be considered without any loss of generality as state feedback control laws for systems with linear dynamics. Therefore, this work attempts to estimate dynamical system states through a novel state observer that does not require injecting the dynamical system outputs onto the observer structure during its design. A linear quadratic optimal control law is then realized based on the estimated states which allows controlling motion along with active vibration suppression of this class of dynamical systems with inaccessible outputs. Validity of the proposed control framework is evaluated experimentally

Predictive input delay compensation for motion control systems

This paper presents an analytical approach for the prediction of future motion to be used in input delay compensation of time-delayed motion control systems. The method makes use of the current and previous input values given to a nominally behaving system in order to realize the prediction of the future motion of that system. The generation of the future input is made through an integration which is realized in discrete time setting. Once the future input signal is created, it is used as the reference input of the remote system to enforce an input time delayed system, conduct a delay-free motion. Following the theoretical formulation, the proposed method is tested in experiments and the validity of the approach is verified

Disturbance Observer-based Robust Control and Its Applications: 35th Anniversary Overview

Disturbance Observer has been one of the most widely used robust control tools since it was proposed in 1983. This paper introduces the origins of Disturbance Observer and presents a survey of the major results on Disturbance Observer-based robust control in the last thirty-five years. Furthermore, it explains the analysis and synthesis techniques of Disturbance Observer-based robust control for linear and nonlinear systems by using a unified framework. In the last section, this paper presents concluding remarks on Disturbance Observer-based robust control and its engineering applications.Comment: 12 pages, 4 figure