Model-reference based wave-variable force control

This paper describes the design and implementation of a Model Reference Adaptive Controller (MRAC) for force control in milling. First, previous work in this area is discussed. Results from previous work on the performance of fixed gain process controllers is summarized. The design of an MRAC for force control in milling is described, including a discussion of the implementation issues of noise and computational speed. The adaptive controller was found to perform more satisfactorily than fixed gain controllers, but is difficult to implement and tune, primarily because of the unmodeled dynamics or measurement noise resulting from runout on the milling cutter. In this problem there was sufficient separation between the noise and the signal frequency that the noise could be filtered. However, the addition of the filter added additional dynamics to the system which reduced the overall performance from that expected from digital simulations.

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Wave Variable Based Force Control

Volume 9: Mechanical Systems and Control, Parts A, B, and C ◽

10.1115/imece2007-41469 ◽

2007 ◽

Author(s):

J. Scot Hart ◽

Gu¨nter Niemeyer

Keyword(s):

Time Delay ◽

Force Control ◽

Time Delays ◽

Communication Channel ◽

Force Feedback ◽

Low Frequency ◽

Force Sensor ◽

Wave Variable ◽

Communication Time ◽

Frictional Forces

Wave variable controllers maintain passive communication across time delays in telerobotics. As passive elements, wave variable controllers interact well with other passive elements, such as P.D. controllers and masses, and use a combination of force and velocity signals to apply force feedback. Currently we are exploring the use of wave variable controllers with large non-backdrivable industrial-type slave devices where dynamics are dominated by inertial and frictional forces. The objective is to integrate force sensor measurements into wave variable controllers to provide low frequency force feedback and hide the slave’s friction and inertia from the user in the presence of a communication time delay. This paper presents and uses a wave variable based approach to design force control. The resulting wave variable based force controller is converted to power variables and shown to be similar to traditional force controllers. A 1-DOF telerobotic system is used to experimentally show the wave variable based force control combines with the enhanced stability properties of the wave communication channel to produce robust slave side force control. The resulting system is better able to maintain force control with rigid environments then a traditional controller both with and without communication time delay.

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Adaptive Control Design and Stability Analysis of Robotic Manipulators

Actuators ◽

10.3390/act7040089 ◽

2018 ◽

Vol 7 (4) ◽

pp. 89 ◽

Cited By ~ 1

Author(s):

Bin Wei

Keyword(s):

Adaptive Control ◽

Control System ◽

Stability Analysis ◽

Motion Control ◽

Force Control ◽

Control Design ◽

Robotic Manipulators ◽

Model Reference Adaptive Control ◽

Model Reference ◽

Model Reference Adaptive

In this paper, the author presents the adaptive control design and stability analysis of robotic manipulators based on two main approaches, i.e., Lyapunov stability theory and hyperstability theory. For the Lyapunov approach, the author presents the adaptive control of a 2-DOF (degrees of freedom) robotic manipulator. Furthermore, the adaptive control technique and Lyapunov theory are subsequently applied to the end-effector motion control and force control, as in most cases, one only considers the motion control (e.g., position control, trajectory tracking). To make the robot interact with humans or the environment, force control must be considered as well to achieve a safe working environment. For the hyperstability approach, a control system is developed through integrating a PID (proportional–integral–derivative) control system and a model reference adaptive control (MRAC) system, and also the convergent behavior and characteristics under the situation of the PID system, model reference adaptive control system, and PID+MRAC control system are compared.

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