As industry heads to an era of high productivity and energy efficiency, the manufacturing of robotic manipulators moves far from the traditionally heavy and stiff structures. Therefore, rigid body ...dynamic models become obsolete and the need for new dynamic models accounting for the flexibility of industrial manipulators emerges. To this end, a physics-based approach considering the flexibility of robots’ links and gearboxes is presented. In particular, this paper intends to provide a framework for modelling flexible robotic structures’ towards increasing their accuracy. The robot components’ elasticity is introduced in a lumped parameters model by pairs of springs and dampers, the number of which is affected by the target of keeping the computational effort and run time of the simulation at levels allowing for the integration of the model in industrial environments. Finally, the proposed model considers the activation of the robots’ Digital Twins aiming to enable the use of the model in a series of applications e.g. predictive maintenance, energy efficiency optimization etc.
Machining using industrial robots is currently limited to applications with low geometrical accuracies and soft materials. This paper analyzes the sources of errors in robotic machining and ...characterizes them in amplitude and frequency. Experiments under different conditions represent a typical set of industrial applications and allow a qualified evaluation. Based on this analysis, a modular approach is proposed to overcome these obstacles, applied both during program generation (offline) and execution (online). Predictive offline compensation of machining errors is achieved by means of an innovative programming system, based on kinematic and dynamic robot models. Real-time adaptive machining error compensation is also provided by sensing the real robot positions with an innovative tracking system and corrective feedback to both the robot and an additional high-dynamic compensation mechanism on piezo-actuator basis.
This paper introduces for the first time the design, modelling, and control of a novel morphing multi-rotor Unmanned Aerial Vehicle (UAV) that we call the OmniMorph. The morphing ability allows the ...selection of the configuration that optimizes energy consumption while ensuring the needed maneuverability for the required task. The most energy-efficient
uni-directional thrust
(UDT) configuration can be used, e.g., during standard point-to-point displacements.
Fully-actuated
(FA) and
omnidirectional
(OD) configurations can be instead used for full pose tracking, such as, e.g., constant attitude horizontal motions and full rotations on the spot, and for full wrench 6D interaction control and 6D disturbance rejection. Morphing is obtained using a single servomotor, allowing possible minimization of weight, costs, and maintenance complexity. The actuation properties are studied, and an optimal controller that compromises between performance and control effort is proposed and validated in realistic simulations. Preliminary tests on the prototype are presented to assess the propellers’ mutual aerodynamic interference.
In this paper, we propose a simulation application that allows an aerial vehicle to land autonomously on a moving platform in the presence of uncertainties and disturbances. We have tested our method ...with various speeds and positions for the landing platform. In the context of this article, the autonomous control of landing on mobile platforms consists in synchronizing the movement of an aerial vehicle with the movement of the mobile platform. As a first step, the Spacelab INCAS laboratory group has developed an offline simulation application that allows an ABB robot to receive information on the movement of a Stewart-type mobile platform in order to conduct a landing process. The application can initiate a landing process on the mobile platform and guide the vehicle for perfect docking on the platform. Offline simulation allows the study of several scenarios of a robot working cell - the mobile platform before setting up the production cell. The offline application has a distributed client-server structure. The client communicates with the server through specific communication protocols. The client and server can reside on the same computer. The client application is developed in the Matlab environment and has as object the simulation and programming of the PS-6TL-1500 platform; the server one simulates and programs an ABB 7600-500/2.55 robot that moves on the track, in the RAPID language under RobotStudio ABB simulator.
Soft robots made of hydrogels are suited for underwater exploration due to their biocompatibility and compliancy. Yet, reaching high dexterity and actuation force for hydrogel-based actuators is ...challenging. Meanwhile, real-time proprioception is critical for feedback control. Moreover, sensor integration to mimic living organisms remains problematic. To address these challenges, we introduce a hydrogel actuator driven by hydraulic force with a fast response (time constant 0.83 s). The highly stretchable and conductive hydrogel (1400% strain) is molded into the PneuNet shape, and two of them are further assembled symmetrically to actuate bi-directionally. Then, we demonstrate its bionic application for underwater swimming, showing 2 cm/s (0.19 BL/s) speed. Inspired by biological neuromuscular systems’ sensory motion, which unifies the sensing and actuation in a single unit, we explore the hydrogel actuator’s self-sensing capacity utilizing strain-induced resistance change. The results show that the soft actuator’s proprioception can monitor the undulation in real-time with a sensitivity of 0.2%/degree. Furthermore, we take a finite-element method and first-order differential equations to model the actuator’s bending in response to pressure. We show that such a model can precisely predict the robot’s bending response over a range of pressures. With the self-sensing actuator and the proposed model, we expect the new approach can lead to future soft robots for underwater exploration with feedback control, and the underlying mechanism of the undulation control might offer significant insights for biomimetic research.
It is to be expected that space robotics systems will develop more and more in the future spatial applications. One of the most challenging and risky missions for spacecraft is to perform ...autonomously Rendezvous and Docking (RvD) in space. This paper describes a hardware-in-the-loop RvD simulation facility which uses two ABB industrial robots to simulate the 6-DOF dynamic manoeuvring of the rendezvous process. Firstly, we also simulate the real robots and we deduce the kinematic and dynamic equations of space robotic system, then the trajectory is planned. The target motion is reduced only to the movement of the end-effector, but the chaser’s motion is based on the plan which solves the inverse kinematic equations, considering the movement limitations of the joints. Finally, a 3D simulation system was developed to evaluate the proposed method using Matlab/ Simulink environment. Simulation results verified the corresponding method and algorithms.
Robot simulators are useful tools for developing robot behaviour. They provide a fast and efficient means for testing robot control code at the convenience of the office desk. In all but the simplest ...cases though, due to complexities of physical systems modelled in the simulator, there are considerable differences between the behaviour of the robot in the simulator and that in the real world environment.
In this paper we present a novel method to create a robot simulator using real sensor data. Logged sensor data are used to construct a mathematically explicit model (in the form of a NARMAX polynomial) of the robot’s environment. The advantage of such a transparent model –in contrast to opaque modelling methods such as artificial neural networks –is that it can be analysed to characterise the modelled system, using established mathematical methods.
In this paper we compare the behaviour of the robot running a particular task in both the simulator and the real-world using qualitative and quantitative measures including statistical methods to investigate the faithfulness of the simulator.
Increasing amounts of robotics applications and possible job opportunities in the industry within the robotics field encourage more universities to involve robotics subject in their current programs ...or incorporate robotics engineering as a new department. This highlights the importance of comprehensible robotics teaching for more people with various levels of technical background. One of the major subjects at the university level in robotics education is representing the physical robot model using mathematical notations. The majority of the current teaching methods of robotics theory for undergraduate students use conventional approaches from robotics books which relies on 3D pictures and sketches for illustration. There are a few modern approaches where the book chapters are linked to supplemental videos, however, the lack of interaction diminishes the student engagement. Moreover, there are some simulators to enhance visual and interactive skills, but they are either costly or robot specific and require adequate competence of programming skills on the associated programming language. In this paper, a serious game to be used in robotics teaching for bachelor students with various technical backgrounds is presented. The game combines the traditional notations in robot modelling with a gamified approach so that the students can comprehend and imagine easier.
This paper addresses the boundedness property of the inertia matrix and the skew-symmetric property of the Coriolis matrix for vehicle-manipulator systems. These properties are widely used in ...Lyapunov-based stability proofs and are therefore important to identify. For example, the skew-symmetric property does not depend on the system at hand, but on the choice of parameterisation of the Coriolis matrix, which is not unique. It is the authors' experience that many researchers take this assumption for granted without taking into account that there exist several parameterisations for which this is not true. In fact, most researchers refer to references that do not show this property for vehicle-manipulator systems, but for other systems such as single rigid bodies or manipulators on a fixed base. As a result, the otherwise rigorous stability proofs fall apart. In this paper we point out several references that are widely used, but that do not show this property and we refer to the correct references. As most references on this topics are not easily accessible, we also give the correct proofs for commonly used parameterisations of the Coriolis matrix and thus provide a proof for future reference.
The same is the case for the boundedness property of the inertia matrix which for a bad choice of state variables will not necessarily hold. This can be solved by deriving the dynamics for vehicle-manipulator systems in terms of quasi-velocities, which allows us to describe the dynamics without the presence of the Euler angle singularities that normally arise in vehicle-manipulator dynamics. To the authors' best knowledge we derive for the first time the dynamic equations with both the skew-symmetric property of the Coriolis matrix and the boundedness property of the inertia matrix for vehicle-manipulator systems with non-Euclidean joints.
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