Nonlinear control of parallel manipulators for very high accelerations without velocity measurement: stability analysis and experiments on Par2 parallel manipulator

Abstract

This paper presents a comparison between control/state estimation methods applied on Par2 parallel manipulator for pick-and-place applications as well as a discussion about the mechanical vibrations issue that may become important when reaching very high accelerations. Real-time experiments were performed first to compare two controllers (a linear Proportional-Derivative controller and a nonlinear/adaptive Dual Mode (DM) controller) complied with the same High-Gain Observer (HGO) to estimate articular velocities, and second to compare three state observers (a Lead-lag-based, an Alpha-beta-gamma (ABG) and an HGO) complied with the same nonlinear DM controller. The stability analysis of the Par2 robot under the control of the proposed DM controller (complied with the HighGO for joint velocity estimation) is also provided. Some small mechanical vibrations were noted when reaching 20 G acceleration, which means that it can become an important issue for higher accelerations. Some suggestions are then made for future investigations to avoid/damp these vibrations.

A new time-varying feedback RISE control for second-order nonlinear MIMO systems: theory and experiments

“…Some controllers that have a priori knowledge about the dynamics of the parallel robot such as: computed-torque control (Codourey, 1998), augmented nonlinear PD (Shang et al, 2009), PD with computed feedforward (Saied, Chemori, El Rafei, Francis, & Pierrot, 2018), dual-space control (Natal, Chemori, & Pierrot, 2015). In addition, the dynamic adaptive controllers that can calibrate the system parameters online include: RISE-based adaptive control , DCAL (Bennehar et al, 2016), nonlinear dual-mode adaptive Control (Natal, Chemori, & Pierrot, 2016), adaptive terminal sliding mode control (Bennehar, El Ghazaly, Chemori, & Pierrot, 2016), L1 adaptive control with adaptive feedforward (Bennehar, Chemori, Pierrot, & Creuze, 2015).…”

Design of Cherry-Picking Manipulator Based on PLC High Speed Parallel Automation Control

“…The embedded soft PLC prototype system mainly includes the editing system of ladder diagram of upper computer, serial communication system, instruction interpretation system of lower computer and input and output system. The embedded soft PLC system can well realize the basic functions of traditional PLC system and simplify the instruction interpretation system of PLC through PLC instructions [2].…”

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