Mechatronic Subsystems Research Articles

Hybrid additive robotic workcell for autonomous fabrication of mechatronic systems - A case study of drone fabrication

• A hybrid additive manufacturing / pick-n-place robotic workcell enables autonomous, flexible fabrication of full-scale functional mechatronic systems. • A modular electronics concept is demonstrated to enable error-free autonomous, robotic construction of full-scale mechatronic sub-systems. • The workcell's functionality is verified through the back-to-back manufacture of different drone designs that are able to fly directly from the build platform. • Functional drones are rapidly manufactured at the point of need in under four hours This paper presents the realization of a robotic workcell capable of autonomous, flexible, fabrication of complete, full-scale, functional mechatronic systems. Using a 6-DOF robotic arm with a hybrid additive manufacturing (AM)/pick-and-place (PnP) end-effector, the workcell can rapidly print enclosures, insert and wire functional electronics, and embed them into the printed structure. The workcell's scalable control system, digital workflow for creating assembly instructions, hybrid AM/PnP toolhead design, and autonomous part tending mechanism are detailed. In addition, a modular electronics infrastructure is presented to enable facile, error-free robotic wiring of large-gauge copper wire. The workcell's ability to manufacture is verified in a case study wherein it is used to autonomously fabricate a variety of Unmanned Aerial Systems (UAS). In the study, the workcell produces a functional quadrotor drone, releases the drone from the workcell, and allows the drone to record the workcell constructing a second, different drone - all without human involvement. The resulting workcell, which combines digitally-integrated manufacturing, robotics and automation, and hybrid process manufacturing, enables autonomous manufacture of complete, functional mechatronic systems that are tailored to custom design needs in a just-in-time manner.

Design of a novel deployable mechanism for capturing tumbling debris

Large quantities of man-made debris from decades of space exploration threaten the safety of future space activities. It is therefore urgent to perform active debris removal missions to maintain access to usable orbital space. This paper proposes a novel deployable end-effector and detumbling mechanism to capture tumbling debris. Three mechatronic subsystems for capture, transmission, and actuation are highly integrated in the end-effector, allowing compact storage during space transport. Grippers composed of constant-torque hinges endow the mechanism with a deployable function and ensure a steady envelope by means of caging, without the need for precise tracking and complex control. With only one actuator, simultaneous motion of the six grippers is implemented by arranging gears in a unique manner. The grippers are optimally designed to enlarge their envelope while reducing weight. A contact detumbling mechanism, composed of three dampers along three axes, is also provided based on revolute friction to slow tumbling debris with residual angular momentum. Two slip rings are ingeniously embedded in each damper to transmit electricity under conditions of signal interference and cable interwinding. Simulations of capturing and detumbling demonstrate the feasibility and effectiveness of the proposed mechanism.

Hardware-in-the-Loop Simulation for a Multiaxial Suspension Test Rig with a Nonlinear Spatial Vehicle Dynamics Model

Hardware-in-the-Loop (HiL) simulations where a mechatronic system is used as the device under test (DUT), are established in the automotive sector for the design of active suspension components, e.g. roll-stabilizers. Usually, uniaxial actuator systems within the test rig are applied for the excitation of the DUT. However, in the context of mechatronic suspension systems incorporating multiple mechatronic subsystems, more sophisticated HiL test rigs / simulations with multiaxial excitation of the DUT are necessary. This contribution presents the model-based design of a HiL simulation for a multiaxial vehicle axle test rig. Within the HiL simulation a nonlinear spatial vehicle dynamics model with 36 states is used to reproduce the environment of the DUT in real-time. The implemented model and its requirements are described in detail. An appropriate HiL control framework is developed, which combines the vehicle dynamics model with the hybrid motion/force control of the manipulator systems. The primary actuator is a hydraulic hexapod. Simulation results and measurements obtained with the HiL system show the effectiveness of this approach. The potential for chassis control validation and design is highlighted in comparison to a highly detailed benchmark vehicle dynamics model.

Valkyrie: NASA's First Bipedal Humanoid Robot

In December 2013, 16 teams from around the world gathered at Homestead Speedway near Miami, FL to participate in the DARPA Robotics Challenge (DRC) Trials, an aggressive robotics competition partly inspired by the aftermath of the Fukushima Daiichi reactor incident. While the focus of the DRC Trials is to advance robotics for use in austere and inhospitable environments, the objectives of the DRC are to progress the areas of supervised autonomy and mobile manipulation for everyday robotics. NASA's Johnson Space Center led a team comprised of numerous partners to develop Valkyrie, NASA's first bipedal humanoid robot. Valkyrie is a 44 degree‐of‐freedom, series elastic actuator‐based robot that draws upon over 18 years of humanoid robotics design heritage. Valkyrie's application intent is aimed at not only responding to events like Fukushima, but also advancing human spaceflight endeavors in extraterrestrial planetary settings. This paper presents a brief system overview, detailing Valkyrie's mechatronic subsystems, followed by a summarization of the inverse kinematics‐based walking algorithm employed at the Trials. Next, the software and control architectures are highlighted along with a description of the operator interface tools. Finally, some closing remarks are given about the competition, and a vision of future work is provided.

Computer Aided Process of Designing the Mechatronic Silesian Greenpower Electric Car

"The Greenpower Corporate Challenge" is an annual race of four-wheeled electric vehicles organized on the tracks in the UK. Participants of the "The Greenpower Corporate Challenge" contest are students of high schools and universities which are involved in designing and construction process of an electric race car. The basic goal of GPCC competition is making the largest possible number of laps on the race track - for a limited time of 90 minutes. The main restriction is imposed by the organizers, the power source and type of the motor driving the car, which increases competition level and equalize the chances of teams. The design process of the vehicle was followed by the drawn intuitively, an iterative procedure. A simplified methodology for the design and construction of the vehicle has been adopted, which was based on a cyclic process of designing every mechatronic subsystems and gathering them all in one CAD model. During all designing and engineering tasks a mathematical model of the vehicle has been used. With using finite element method (FEM) and studies using an anthropometric drivers model there was a continuous control of the correctness of the solutions and results. This article describes the computer research methods used in the design process of selected systems and components of the vehicle Silesian Greenpower and their adequacy in relation to traditional methods.

Methodological proposal for Accelerated Screening Test design on stepper motors

In the industrial world the need to guarantee a product out of the infant mortality zone has become almost imperative. Stress screening testing of mechatronic subsystems under nominal operating conditions may be time- and resource-consuming, making sometimes such procedures expensive and impractical. As a result, technologies for accelerated testing have been developed, to design high level stress tests (e.g. temperature, voltage, pressure, corrosive media, load, vibration, etc.) by means of thermal chambers and shakers which stimulate the device under test with external stresses. However, not all industries have access to such expensive equipment.In this research, a methodology for implementing Accelerated Screening Test by varying internal system variables is proposed and applied to a subsystem with a stepper motor. Some interesting preliminary experimental results are reported and commented. Accelerated Screening Test has the aim to precipitate early failures without inducing fatigue failure mechanisms. Actually this kind of procedure is difficult to optimize and requires some concern to model the infant mortality. This paper investigates also the use of Accelerated Screening Test for the characterization of a subsystem, to demonstrate the general validity of the proposed methodology.

Effective method for creating engineering checklists

This paper presents the results of an empirical study of a project whose aim was to develop a driveline for commercial vehicle applications containing a totally new mechatronic sub-system with a significant amount of new functions and interfaces. The purpose of the empirical study was to identify areas where explicit knowledge management efforts are needed in the development process of a mechatronic systems integrator. The results show that the management of knowledge related to component/system interfaces is not addressed neither in the state of practice nor the state of the art. Based on these findings, the method of engineering checklists to manage interface-related knowledge was found suitable. Methods on how to implement engineering checklists however are largely lacking and the main contribution of this paper is a method dedicated to creating engineering checklists from a knowledge management perspective. The evaluation of the developed method indicates a high level of both usefulness and usability of the method in the processes of the studied company along with potential improvement mainly regarding the instructions for the application of the method.

Mechatronic system reliability modelling and analysis: a graph theoretic approach

This paper presents a unique systems approach for reliability modelling analysis of a mechatronic system. As a first step, a reliability graph, which is useful in visual analysis of reliability interactions among the mechatronic subsystems, is developed. Information stored in this graph is quantified and exported to a reliability variable permanent matrix and finally to a function named Mechatronic Variable Permanent Reliability Function (MVPRF). Reliability analysis of mechatronic systems is done on the basis of MVPRF. A reliability index based on the MVPRF is proposed for reliability evaluation. Coefficient of similarity and dissimilarity useful for a designer in structure and reliability-based comparison of mechatronic systems is proposed. This methodology would be useful for a designer to conduct structure-based reliability analysis of a mechatronic system and also for a maintenance engineer to monitor the health condition of mechatronic system during the service period. The proposed methodology is explained with the help of an illustrative example.

Mechatronic Subsystem Studied of Approximate Method Modeled by Hypergraph

AbstractThe transverse vibrating mechatronic subsystem is considered. Integral parts of this system are: a continuous beam with known boundary conditions and a transducer, extorted by harmonic voltage excitation, to be perfectly bonded to the beam surface. Findings this article are dynamical characteristics of the discussed mechatronic and mechanical system to model them by hypergraphs. Research limitation is that the linear mechanical subsystem and linear electric subsystem of mechatronic system has been considered, however for this kind of systems the approach is sufficient. Practical implications of this researches was that global approach is presented, that means in the domain of frequency spectrum analysis. The methods of analysis and obtained results can be base of design and investigation for this type of mechatronic systems. Originality of this paper is that the mechatronic system created from mechanical and electric subsystems with electromechanical bondage has been considered. This approach is different from those considered so far because is it relies on application approximate methods of analysis of mechatronic subsystem and modeling the one by hypergraph [1‐7]. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Improved handling characteristics of off-road vehicles by applying active control of steering wheel torque

Driving speed of agricultural mobile machines have been increased in the recent years, raisingserious questions about vehicle handling characteristics considering the high center-of-gravity, multi-massconfiguration and rear-wheel-steering of these vehicles. The next generation of steering systems on offroad vehicles will incorporate a steering column mechatronic subsystem which will generate tactilefeedback for operator. This paper presents our research work to utilize steering wheel torque to improveoff-road vehicle handling characteristics.

Design of piezo-based AVC system for machine tool applications

The goal of machine tools for Ultra High Precision Machining is to guarantee high specified performances and to maintain them over life cycle time. In this paper the design of an innovative mechatronic subsystem (platform) for Active Vibration Control (AVC) of Ultra High Precision micromilling Machines is presented. The platform integrates piezoelectric stack actuators and a novel sensor concept. During the machining process (e.g. milling), the contact between the cutting tool and the workpiece surface at the tool tip point generates chattering vibrations. Any vibration is recorded on the workpiece surface, directly affecting its roughness. Consequently, uncontrolled vibrations lead to poor surface finishing, unacceptable in high precision milling. The proposed Smart Platform aims to improve the surface finishing of the workpiece exploiting a broadband AVC strategy. The paper describes the steps throughout the design phase of the platform, beginning from the actuator/sensor criteria selection taking into account both performance and durability. The novel actuation principle and mechanism and the related FE analysis are also presented. Finally, an integrated mechatronic model able to predict in closed-loop the active damping and vibration-suppression capability of the integrated system is presented and simulation results are discussed.

A scaled roller test rig for high-speed vehicles

Scaled roller rigs are quite widespread among railway research centres, and several examples are described in the literature. Due to their low costs and ease of use compared with full-scale counterparts, these types of rigs are used for a wide range of studies concerning dynamical stability, comfort, mechatronic subsystem and wear. Furthermore, scaled roller rigs can be a powerful education tool for railway engineering students. In this paper, the design and the main features of the scaled rolled rig that will be installed in the Mechatronics and Dynamic Modeling Laboratory of the University of Florence located in Pistoia, Italy, are described. The main feature of the proposed rig will be the simulation of degraded adhesion conditions. This feature is very important for hardware-in-the loop testing of many safety relevant on-board subsystems like wheel slide protection systems, traction and stability controls, odometry and automatic train protection and control.

Cooperative body–brain coevolutionary synthesis of mechatronic systems

AbstractTo support the concurrent design processes of mechatronic subsystems, unified mechatronics modeling and cooperative body–brain coevolutionary synthesis are developed. In this paper, both body-passive physical systems and brain-active control systems can be represented using the bond graph paradigm. Bond graphs are combined with genetic programming to evolve low-level building blocks into systems with high-level functionalities including both topological configurations and parameter settings. Design spaces of coadapted mechatronic subsystems are automatically explored in parallel for overall design optimality. A quarter-car suspension system case study is provided. Compared with conventional design methods, semiactive suspension designs with more creativity and flexibility are achieved through this approach.

Two distinct methods for integration of active differential and active roll control systems

The development and application of mechatronic sub-systems has dramatically increased in the automobile industry during recent years. The implementation of these sub-systems, aboard vehicles, has resulted in an increase in vehicle performance and stability. However, until recently, these sub-systems have been developed for specific objectives without considering the dynamic coupling between these systems. Hence, their potential has not been fully exploited. In this paper, the coupling effect of the active differential and the active roll control systems on the lateral and the yaw rate dynamics of a vehicle are demonstrated by deriving a simple linearised model. Then, two distinct control strategies are proposed for illustrating the benefits of integrating the aforementioned systems. The first control method is based on direct use of an optimisation method for computing optimal mapping of the requested vehicle body forces to the actuator inputs. The second method utilises a MIMO model based control methodology. The advantages and the drawbacks of each control strategy are discussed and the simulation results are presented.

Principles and Synthesis of Hydractive CRONE Suspension

Mechatronic subsystems have been extensively developed in automotive applications as they increase performance compared to passive components. The Hydractive CRONE suspension based on fractional differentiation is presented as a hybrid system undergoing an infinite sequence of autonomous switchings. The modelling and operation of Hydractive CRONE suspension as a hybrid system are presented. The stability of Hydractive CRONE suspension is demonstrated using the maximum principle extended to hybrid systems. Finally, comfort mode synthesis is proposed using the third generation CRONE control system design.

Architectural design of integrated external speed adaptation with collision avoidance system for intelligent trucks

In this paper, the design and development cycle for integrated systems architecture for External Speed Adaptation (ESA) and Collision Avoidance Systems (CAS) is presented. It subsequently presents a new method of modelling the integrated system architecture based on structured analysis. Moreover, a vehicle kinematics model is developed and used as the basis for designing the systems decision logic. A description of an experimental hardware and CAN software simulation show the potential of the systems integration. In the experimental system, the speed limiter (vehicle throttle control and ECU) is a mechatronic sub-system and the collision avoidance system that deactivates the acceleration of the truck and controls the speed of the truck to a preset speed limit to avoid collision. This is based on communication between a roadside sensor and the vehicle and an interface between the collision avoidance and speed adaptation systems.

Modelling of Hydractive CRONE Suspension as a Hybrid System

Mechatronic subsystems have been extensively developed in automotive applications as they increase performance compared to passive components. The modelling and operation of Hydractive CRONE suspension as a hybrid system are now presented

Feedforward and Crone Feedback Control Strategies for Automobile ABS

Summary As mechatronic subsystems and especially new emerging technologies for brake systems are more and more developed, a new control architecture for ABS is proposed. The control architecture is designed using both feedback and feedforward controls that command pressure-controlled proportional servo-valves. The methods are developed to compensate for the uncertainty associated with the state of the road surface. The advantages of this strategy compared to the existing ABS strategy are discussed including simulations results using a complete vehicle and brake system model.