A Discrete Model-Free Scheme for Fault-Tolerant Tracking Control of Redundant Manipulators

Abstract

Fault tolerance is a critical requirement for robust motion control of redundant robotic manipulators. This task aims to endow the redundant manipulator with the capability to achieve the required path of end-effector in the condition that one or some of its joints' motion fail. Although many fault-tolerant control algorithms of redundant manipulator have been proposed in recent years. However, few of them are on the basis of the condition that the robotic model is unknown. The complexity of the calculation model limits the efficiency and portability of these algorithms. For the first time, we proposed a discrete model-free fault tolerant tracking control (DMFFTC) scheme of redundant manipulator, which takes into account the fault tolerance in the control system of redundant manipulator by formulating it into a quadratic programming (QP) framework. The core of the proposed scheme consists of a discrete kinematic estimator and a discrete QP solver, powered by which the fault-tolerant control problem is transformed into a unified computing problem relaxing the need of knowing the redundant manipulator's kinematic model. A discrete joint space observer is proposed for detection of the happening of faulty states. Extensive simulations and experiments based on a redundant manipulator are performed and analyzed to support the verification of the efficiency and effectiveness of the proposed scheme.

Continuous and low-carbon production of biomass flash graphene

“…1 – 6 , and Table 1 , 2 ). Instead of performing manual loading and unloading, robotic arms were constructed to achieve continuous biomass FG production 35 , 36 . However, a small cumulative deviation may exist between the coordinate systems of the robot arms and the sample tray, resulting in samples not being successfully grabbed.…”

“…The carbon content of the sawdust FG was up to ~97.3%, indicating that the as-synthesized biomass FG had a high purity due to the low impurity content in the parent biomass (Supplementary Figs. 35,36 and Tables 10 and 11). Sawdust FG exhibited excellent dispersibility, catalytic (bromate removal, ~93.3%) and solar absorption (~92.4%) performance, which are comparable to those of common catalytic and photothermal materials [38][39][40] (Supplementary Figs.…”

Seeking Nash Equilibrium in Non-Cooperative Differential Games

“…Although the assumption we have might not get satisfied in all active defense problems, the problem of active defense that is occurring in the end game often follows a similar dynamic as the one proposed in this paper. Moreover, although kinematic control of a single manipulator system is well studied by different methods such as Neural-network (Li and Li, 2021; Tan et al, 2022), and variable damping control (Zahedi et al, 2021; Zahedi et al, 2022), one can go beyond the direct capabilities of our proposed algorithm, and extend the problem to be applicable to kinematic control of multi-manipulator systems.…”

H∞$$ {H}_{\infty } $$ optimal output tracking control for Markov jump systems: A reinforcement learning‐based approach

“…26 Tracking control expects the system state or output to be consistent with the target signal, which is widely used in engineering practice. The work 27 has proposed a model-free fault-tolerant tracking controller for redundant robotic arm by transforming the tracking control problem into a quadratic DP problem. For distributed event-triggered formation tracking control problem of unicycle-type mobile robots, the work 28 has proposed a distributed formation tracking controller based on trigger sampling information to achieve convergence of closed-loop errors.…”