Towards Cable Parallel Robot Simulation for Control End Effector Position

In this paper, we present a Graphical User Interface (GUI) simulator that has been developed using robust generalize predictive control. The proposed control technique is used for dealing with linear system uncertainties. The main contribution of this work is firstly: a graphical user interface has been developed and implemented based on geometric model , in order to, control the position of the end effector with several spatial tests. Secondly, we study the response of differential equations for our system with the proposed control for different trajectories in order to test the accurate tracking of the robot for desired trajectory simulation using MATLAB/Simulink. The Simulation results are carried out to prove the feasibility and effectiveness of the strategy outlined here

Cable Robot Performance Evaluation by Wrench Exertion Capability

Although cable driven robots are a type of parallel manipulators, the evaluation of their performances cannot be carried out using the performance indices already developed for parallel robots with rigid links. This is an obvious consequence of the peculiar features of flexible cables-a cable can only exert a tensile and limited force in the direction of the cable itself. A comprehensive performance evaluation can certainly be attained by computing the maximum force (or torque) that can be exerted by the cables on the moving platform along a specific (or any) direction within the whole workspace. This is the idea behind the index-called the Wrench Exertion Capability (WEC)-which can be employed to evaluate the performance of any cable robot topology and is characterized by an efficient and simple formulation based on linear programming. By significantly improving a preliminary computation method for the WEC, this paper proposes an ultimate formulation suitable for any cable robot topology. Several numerical investigations on planar and spatial cable robots are presented to give evidence of the WEC usefulness, comparisons with popular performance indices are also provided

Optimal Force Allocation for Overconstrained Cable-Driven Parallel Robots: Continuously Differentiable Solutions With Assessment of Computational Efficiency

In this article, we present a novel method for force allocation for overconstrained cable-driven parallel robot setups that guarantees continuously differentiable cable forces and allows for small penalized errors in the resulting wrench. For the latter, we also provide a bound on the error under some assumptions. We study real-time feasibility by performing numerical simulations on a large set of configurations.acceptedVersio

The Robotic Lumbar Spine: Dynamics and Feedback Linearization Control

The robotic lumbar spine (RLS) is a 15 degree-of-freedom, fully cable-actuated robotic lumbar spine which can mimic in vivo human lumbar spine movements to provide better hands-on training for medical students. The design incorporates five active lumbar vertebrae and the sacrum, with dimensions of an average adult human spine. It is actuated by 20 cables connected to electric motors. Every vertebra is connected to the neighboring vertebrae by spherical joints. Medical schools can benefit from a tool, system, or method that will help instructors train students and assess their tactile proficiency throughout their education. The robotic lumbar spine has the potential to satisfy these needs in palpatory diagnosis. Medical students will be given the opportunity to examine their own patient that can be programmed with many dysfunctions related to the lumbar spine before they start their professional lives as doctors. The robotic lumbar spine can be used to teach and test medical students in their capacity to be able to recognize normal and abnormal movement patterns of the human lumbar spine under flexion-extension, lateral bending, and axial torsion. This paper presents the dynamics and nonlinear control of the RLS. A new approach to solve for positive and nonzero cable tensions that are also continuous in time is introduced

Studio teorico e progettazione di un manipolatore per il lancio controllato di organi di presa

L’obiettivo di questa tesi consiste nella realizzazione di un manipolatore robotico in grado di operare su oggetti lontani disposti in uno spazio di lavoro 3-dimensionale. Il lavoro è stato svolto presso il Centro Interdipartimentale di Ricerca “E. Piaggio” della Facoltà di Ingegneria dell’Università di Pisa e si basa su una tecnica robotica chiamata casting manipulation. Questa tecnica consente di dispiegare l’organo terminale di un robot a grande distanza dalla base del robot stesso, lanciandolo e controllando la sua traiettoria in volo mediante forze che sono trasmesse all’organo terminale attraverso un cavo leggero collegato ad esso. Il cavo può inoltre essere usato per recuperare l’organo terminale o per esercitare forze sull’ambiente. In questo lavoro si studiano la cinematica e la dinamica di un manipolatore in grado di raggiungere oggetti a grande distanza e se ne presenta un possibile progetto meccanico. Inoltre si affronta il problema del controllo in tempo minimo della traiettoria dell’organo terminale durante la fase di volo. Tale problema risulta di particolare interesse a causa delle limitazioni sui controlli ammissibili dovuti alla natura stessa del cavo che, come noto, può esercitare solo forze di trazione.L’efficacia della soluzione proposta è stata convalidata attraverso simulazioni

Vibration Control in Cable Robots Using a Multi-Axis Reaction System

The primary motivation of this thesis is to develop a control strategy for eliminating persistent vibrations in all six spatial directions of the end effector of a planar cable-driven parallel robotic manipulator. By analysing the controllability of a cable-driven robot dynamic model, the uncontrollable modes of the robot are identified. For such uncontrollable modes, a new multi-axis reaction system (MARS) is developed. The new MARS that is attached to the end effector is made of two identical pendulums driven by two servo motors. A decoupled PD controller strategy is developed for regulating controllable modes and a hierarchical sliding mode controller is developed for controlling the remaining modes of the cable robot using MARS. The performance of both controllers is studied and shown to be effective in simulation. The controllers are then implemented on an experimental test setup of a planar cable-driven manipulator. Both controllers are shown to completely eliminate the end effector vibrations

Integrated Trajectory-Tracking and Vibration Control of Kinematically-Constrained Warehousing Cable Robots

With the explosion of e-commerce in recent years, there is a strong desire for automated material handling solutions including warehousing robots. Cable driven parallel robots (CDPRs) are a relatively new concept which has yet to be explored for high-speed pick-&-place applications in the industry. Compared to rigid-link parallel robots, a CDPR possesses significant advantages including: large workspace, low moving inertia, high-speed motion, low power consumption, and incurring minimal maintenance cost. On the other hand, the main disadvantages of the CDPRs are the cable’s unilateral force exerting capability and low rigidity which is resulting in undesired vibrations of their moving platform. Kinematically-constrained CDPRs (KC-CDPRs) include a special class of CDPRs which provide a considerably higher level of stiffness in undesired degrees of freedom (DOFs) via connecting a set of constrained cables to the same actuator. Nevertheless, undesired vibrations of the moving platform are still their main problem which request more attention and investigation. Dynamic modeling, stiffness optimization, vibration and trajectory-tracking control, and stiffness-based trajectory-planning of redundant KC-CDPRs are studied in this thesis. As a new technique, we separate the moving platform’s vibration equations from its desired (nominal) equations of motion. The obtained vibration model forms a linear parametric variable (LPV) dynamic system which is based for the following contributions: 1) Proposing a new tension optimization approach to minimize undesired perturbations under external disturbances in a desired direction; and demonstrating the effectiveness of kinematically-constrained actuation method in vibration attenuation of CDPRs in undesired DOFs. 2) Providing the opportunity of using a wide class of well-established robust and optimal LPV-based control methods, such as H∞ control techniques, for trajectory-tracking control of CDPRs to minimize the effect of disturbances on the robot operation; and showing the effectiveness of kinematically-constrained actuation method in control design simplification of such robots. 3) Proposing the concept of stiffness-based trajectory-planning to find the stiffness-optimum geometry of trajectories for KC-CDPRs; and designing a time-optimal zero-to-zero continuous-jerk motion to track such trajectories. All the proposed concepts are developed for a generic KC-CDPR and verified via numerical analysis and experimental tests of a real planar warehousing KC-CDPR

Kinematics and Robot Design I, KaRD2018

This volume collects the papers published on the Special Issue “Kinematics and Robot Design I, KaRD2018” (https://www.mdpi.com/journal/robotics/special_issues/KARD), which is the first issue of the KaRD Special Issue series, hosted by the open access journal “MDPI Robotics”. The KaRD series aims at creating an open environment where researchers can present their works and discuss all the topics focused on the many aspects that involve kinematics in the design of robotic/automatic systems. Kinematics is so intimately related to the design of robotic/automatic systems that the admitted topics of the KaRD series practically cover all the subjects normally present in well-established international conferences on “mechanisms and robotics”. KaRD2018 received 22 papers and, after the peer-review process, accepted only 14 papers. The accepted papers cover some theoretical and many design/applicative aspects

Planar translational cable-direct-driven robots

3nonemixedWILLIAMS R.L; GALLINA P.; JIGAR VWILLIAMS R., L; Gallina, Paolo; Jigar, V