Adaptive robust control and admittance control for contact-driven robotic surface conditioning

Abstract

This work presents a hybrid position/force control of robots for surface contact conditioning tasks such as polishing, profiling, deburring, etc. The robot force control is designed using sliding mode ideas to benefit from robustness. On the one hand, a set of equality constraints are defined to attain the desired tool pressure on the surface, as well as to keep the tool orientation perpendicular to the surface. On the other hand, inequality constraints are defined to adapt the tool position to unmodeled features present in the surface, e.g., a protruding window frame. Conventional and non-conventional sliding mode controls are used to fulfill the equality and inequality constraints, respectively. Furthermore, in order to deal with sudden changes of the material stiffness, which are forwarded to the robot tool and can produce instability and bad performance, adaptive switching gain laws are considered not only for the conventional sliding mode control but also for the non-conventional sliding mode control. A lower priority tracking controller is also defined to follow the desired reference trajectory on the target surface. Moreover, the classical admittance control typically used in force control tasks is adapted for the proposed surface contact application in order to experimentally compare the performance of both control approaches. The effectiveness of the proposed method is substantiated by experimental results using a redundant 7R manipulator, whereas its advantages over the classical admittance control approach are experimentally shown.

Human-Robot Cooperation for Surface Repair Combining Automatic and Manual Modes

“…The complete or partial automation of surface treatment tasks, such as polishing, sanding or deburring, has been the main focus of a growing number of research contributions in the last years. For instance, some works addressed the automation of surface treatment using robotic systems [5]- [7], whereas other works tackled some specific issues, such as detecting wether a polishing operation is complete or the polishing tool needs to be changed [8]. Furhtermore, [9], [10] proposed a human-robot collaboration strategy so that the user guides the robot to perform the treatment on a specific area.…”

“…where M tasks or equalities are considered in (4), which are given by matrix A i and vector b i (i = 1 and i = M denote the highest and lowest priority, respectively), and the solution x M is computed with the recursive formulation given by (5) and (6) in order to minimize the tasks errors, where x 0 = 0 (zero column vector), N 0 = I (identity matrix) and superscript † represents the Moore-Penrose pseudoinverse [34].…”

A Robotic Deburring Methodology for Tool Path Planning and Process Parameter Control of a Five-Degree-of-Freedom Robot Manipulator

“…An application of a human mimicking control strategy that mimics the human behavior during the manual deburring on the deburring of hard material items using an industrial robot was introduced [30]. By satisfying a set of constraints to properly perform the desired surface contact conditioning, a hybrid position/force control approach using task priority and sliding mode control was proposed for contact-driven robotic surface treatments such as deburring [31,32]. A set of optimal process parameter combination for robotic machining and the effect of process parameters such as spindle speed, feed rate and tool path strategies on the performance characteristics were investigated using the Taguchi-Grey relational approach and analysis of variance [33].…”

“…The tool path adaptation for robotic deburring implemented usually needs to supplement extra equipment or processes, e.g., using a vision system described in [27,36] or direct teaching [29]. Other studies on the process parameter control for robotic deburring have certain constraints, e.g., the deburring tool is an abrasive diamond disc in the control strategy for the process parameter control, and other deburring tools are not considered [30]; the designed control action and implementation are more intricate, such as [25,31,32,34,36]; the procedure of the proposed approach is more complicated, such as [33]; or detailed deburring process parameters such as robotic feed and spindle speed for the deburring industrial robot are not considered [35].…”

Study on the compensation control of electro-hydraulic servo force loading in nonlinear variable load condition

“…2 Researches have been done over decades to satisfy the different requirement in different situations. In previous works, 3–7 adaptive control strategies have been proposed to deal with the nonlinearities and uncertainties applied respectively in robots for surface contact conditioning tasks, friction dynamics compensation, robot manipulator, inverter with limited bandwidth and voltage controller based on resonant harmonic filters. Fuzzy controllers have been developed enormously reducing the independence for the mathematical model of the controlled object such as omnidirectional robot, DC servo motor, wind energy system, torque ripple reduction in switched reluctance motor and continuous-time nonlinear systems in Takagi–Sugeno’s form.…”