Mechatronic robot arm with active vibration absorbers

Abstract

Serial robots are typically able to cover large workspace, but their mass/stiffness ratio does not allow combining high accuracy and high dynamic of the end effector operations. Widely spread usage of serial robots, even for tasks such as drilling, leads to high accuracy demands through its workspace. Absolute measurement of the end point for position feedback can be challenging due to objects or even a workpiece in the workspace. Moreover, inbuilt motors of the serial robot cannot response in the frequency range high enough as vibration of the end point. Instead, an additional spring–mass system is attached to the robot to suppress vibrations. The narrow frequency range of a passive dynamic absorber can be extended with active elements between the robot and absorber. An active approach is also necessary because of robots eigenfrequencies and eigenmodes variability. The study deals with a planar flexible robot equipped with a three-degree-of-freedom planar active absorber. The absorber is tuned passively to one value of multiple eigenfrequency. The linear-quadratic regulator control with a state observer has been designed as an active absorber control algorithm. Feedback inputs are absorber body acceleration, end effector acceleration, and relative motions in three absorber actuators realized by voice coils. The end effector vibration suppression along the robot trajectory is achieved using gain scheduling of local controller’s outputs.

Robust Action Governor for Uncertain Piecewise Affine Systems with Non-convex Constraints and Safe Reinforcement Learning

“…3 where the mass moves within a bounded region with the controlled external force F. We impose velocity constraints to the mass when it approaches the boundaries to achieve softlanding. This soft-landing control of the MSD can be used to model motion control of aircarft systems [44], manipulation of robot arms [39,26] and interaction of mobile robots [53]. In particular, in this paper we consider an automated tool-tray transfer systems delivering tools/materials between working stations within an automated assembly line.…”

“…• We demonstrate the effectiveness of the proposed RAG scheme and safe RL framework using an example of softlanding control for a mass-spring-damper system. Such an example is relevant to applications in the ones of aircraft flight control [44], robotic manipulation [26,39] and cooperative navigation [53].…”

Drive axis controller optimization of production machines based on dynamic models

“…In the paper [22], the pole search method is used in conjunction with least squares projection technique for identifying virtual machine tool drives, and it gives servo errors from the desired position with high accuracy. The system residual vibrations could be suppressed by active vibration absorber (delay resonator is presented in [23]) applied to the 2D robotic arm [24,25].…”

Smart structures and materials: Vibration and control

“…Additionally, 176 full papers were included in the e-book proceedings. The four articles in this issue are representatives of the ‘GS03: Smart systems ’ (Kraus et al, 2020), ‘MS07: Modelling and design of smart composite structures ’ (Araújo and Madeira, 2020) and ‘MS10: Vibration mitigation through electromechanical couplings ’ (Guillot et al, 2020; Høgsberg, 2020). These topics are in line with those of JVC, particularly ‘ Adaptive and smart structures ’, ‘ Vibration and control of structures ’, ‘ Vibration and control of machinery ’, ‘ Vibration absorbers ’, ‘ Structural control ’, and ‘ Structural acoustics ’.…”

“…Indeed, Araújo and Madeira (2020) addressed the issue of vibration and noise reduction in laminated sandwich plates using piezoelectric patches with passive shunted damping, while Høgsberg (2020) presented a consistent frequency matching calibration procedure, common for electromagnetic and piezoelectric shunt passive absorbers. On the other hand, Kraus et al (2020) dealt with a planar flexible robot equipped with three degrees of freedom planar active absorbers. Finally, Guillot et al (2020) investigated theoretically and experimentally the 1:3 internal resonance in a cantilever elastically isotropic beam with piezoceramic patches.…”