Development of Advanced CNC Interpolation Algorithm With Consideration of Command and Dynamic Errors

In this paper, an integrated acceleration/deceleration with dynamics interpolation scheme is proposed to confine the maximum contour error at the junction of linear junction. The dynamic contour error equation is derived analytically and then it is utilized for the interpolation design. Based on the derived formulations which could predict the command and dynamic errors, the advanced interpolation design could adjust the connecting velocity of the two blocks to confine the overall contour errors under the given tolerance. Simulation results validate the proposed algorithm can achieve higher accurate trajectory as compared to the other interpolation algorithm proposed in the past.

An Interactive Virtual Environment for Programming Modular Robots

The design of RoboSim, a virtual environment for modular robots which controls simulated robots with code written for the hardware robots without modification, is described in detail in this paper along with its applications in educational environments. RoboSim integrates into the Ch programming environment, a C/C++ interpreter, that provides the ability to remotely control robots through interpreted C/C++ code allowing users to alternate between hardware and virtual robots without modifying the code. Open source software projects Open Dynamics Engine, OpenSceneGraph, and Qt are employed to produce the virtual environment and user interface which provide the capability of running on all major software platforms. The design of the software includes multiple library modules each specific to a particular task; therefore the simulation library and Graphical User Interface (GUI) can link against only the necessary libraries. The GUI links against the graphical library and XML library to give an interactive view of the RoboSim Scene as users are adding robots and obstacles into both the GUI and simulation. Execution of Ch code generates a new RoboSim Scene window which has the entire simulation that utilizes the simulation, graphical, xml, and callback libraries, in addition to the identical Scene from the GUI. It generates its own window for the user to view and interact with the progress of the simulation.

A New Fractional Order Dynamic Model for Human Crowd Stampede System

Tragedies due to people’s crushing or trampling have been observed in recent years. In order to understand the reasons that lead to these accidents, a lot of research has been conducted in modeling or predicting the behavior of crowd pedestrians. A new kind of fractional order dynamic description for crowd-pedestrian system has been developed in microscopic scale in this paper for a better understanding of human collective behavior where fractional order in time domain has been introduced. Due to the freedom provided by Fractional Calculus, a lot of characters of pedestrians can be considered in this fractional order modeling framework, such as memory effects, long range interactions and heterogeneity of each individual. Simulations results using Matlab in microscopic are also presented to show the effects of integer order and fractional order on evacuation time which is useful in evaluating the evacuation process or predicting crowd stampede that is going to occur.

Maximum Power Point Tracking of Proton Exchange Membrane Fuel Cell With Fractional Order Filter and Extremum Seeking Control

Proton Exchange Membrane FC (PEMFC) is widely recognized as a potentially renewable and green energy source based on hydrogen. Maximum power point tracking (MPPT) is one of the most important working conditions to be considered. In order to improve the searching performance such as convergence and robustness under disturbance and uncertainty, a kind of fractional order low pass filter (FOLPF) is applied for the MPPT controller design based on general Extremum Seeking Control (ESC). The controller is designed with FOLPF and high pass filter (HPF) substituting the normal LPF and HPF in the original ESC design. With this FOLPF ESC, better convergence and smooth performance is gained while maintaining the robust specifications. Simulation results are included to validate the proposed new FOLPF ESC scheme under disturbance and comparisons between FOLPF ESC and general ESC method are also provided.

Design and Calibration of a 3D High-Resolution Surface Profiling System Using Photometric Stereo

This paper presents the design and calibration of a 3D high-resolution surface profiling system using photometric stereo (PS). This system is mainly composed of a high resolution DSLR camera with a macro lens facing perpendicularly to the target surface, and several LEDs tilting towards the surface constrained by a light fixture. With each LED turned on at a time to create one lighting direction, the camera fixed at the same position captures an image. PS with surface normal integration (SNI) are then performed to reconstruct the surface in 3D. Methods of four calibrations for the developed system are proposed to achieve better accuracy, which are the camera radiometric calibration, the camera geometric calibration, the light direction calibration and the light intensity calibration. Experiments have demonstrated that the developed system with the calibration processes could achieve the accuracy in the order of 10 microns.

A Gripper for Handling Large Leather Plies Stacked on Beams

The paper presents the preliminary design of a novel gripper able to grasp large non-rigid materials that has been conceived to face the challenge of automatic handling tasks in the leather industry. The design has been driven by the requirements to limit production costs and the complexity of the grasping device. A statistical analysis of the different templates sizes has allowed to identify a fixed configuration of the gripping points able to properly pick all the sheets within a great confidence interval. According to the varying shape of the leather templates themselves, that is due to their stacking in plies on the beam, the trajectory of the gripping points has been studied and arranged. Due to the irregular shape of the large sheets that are handled, the edges of the non-rigid materials out of the gripping area might flutter during the transferring phase: a four-bar linkage has been specifically designed, so that the motion of its end-effector prevents unwanted leather creases.

Software Based Methods to Harden Embedded Software at Run-Time: A Survey

Embedded Systems software reliability is increasingly important, therefore methods to harden existing software are needed. In general, hardening software against various failures is a necessity in modern computer systems. A lot of work has been published regarding many possible ways to achieve this non-functional requirement. Relevant topics include, e.g., test procedures, recommended development flows, and hardware measures like watchdog timers. One of these methods seems very promising to be software implemented in modern embedded systems: Control Flow Checking by signatures. Various authors have shown the effectiveness and feasibility of Control Flow Checking (CFC) by signatures for personal computer software. For instance it has been shown for standard computer-systems, that CFC is capable of reducing undetected control flow errors by at least one magnitude. This survey will focus on the applicability of such software hardening methods to embedded systems, while adhering mainly to software based approaches. Published methods will be summarized and compared. Furthermore methods to simplify derived control-flow graphs to essential states will be emphasized. Finally the possibility to apply run-time verification to the Control-flow Checking Software is considered.

Development of a Control Theoretic Alternative to Fitts’ Law With Application to In-Vehicle Touchscreen Interface

A control theoretic alternative to Fitts’ Law based on a modified crossover model is proposed. A physical interpretation of the model offers the unification of various different formulations of Fitts’ Law. Model identification and validation is carried out for a target acquisition task using a touchscreen. A brief treatment of noise generated by random relative movement between the human operator and the touchscreen (such as in-vehicle touchscreen based devices) is considered using the proposed model.

A Multi-Robot Testbed for Adaptive Sampling Experimentation via Radio Frequency Fields

Adaptive navigation is the process by which a vehicle determines where to go based on information received while moving through the field of interest. Adaptive sampling is a specific form of this in which that information is environmental data sampled by the robot. This may be beneficial in order to save time/energy compared to a conventional navigation strategy in which the entire field is traversed. Our work in this area focuses on multi-robot gradient-based techniques for the adaptive sampling of a scalar field. To date, we have experimentally demonstrated multi-robot gradient ascent/descent as well as contour following using automated marine surface vessels. In simulation we have verified controllers for ridge descent / valley ascent as well as saddle point detection and loitering. To support rapid development of our controllers, we have developed a new testbed using wireless transmitters to establish a simple, large-scale, customizable scalar field based on the strength of the radio frequency field. A cluster of six land rovers equipped with radio signal strength sensors is then used to process sampled data, to make adaptive decisions on how to move, and to execute those moves. In this paper, we describe the technical design of the testbed, present initial experimental results, and describe our ongoing research and development work in the area of adaptive sampling and multi-robot control.

Optimal Manual Control for Heart Rate Tracking During Treadmill Exercises

Recently, a nonlinear dynamic system has been presented to model the heart rate (HR) response during and after treadmill exercise. The parameters of the model can be estimated and individualized. Based on the nonlinear model, several control techniques for the regulation of HR during treadmill exercise have been proposed. But commercial treadmills may not have equipments to be computer-controlled. In this paper, an optimal manual method is presented to track a predefined HR trajectory. A piecewise constant speed profile is considered as the input to the system and computed by an optimization procedure offline. The objective function is constituted in term of heart rate deviation from its desired. The subject must change manually the speed of the treadmill according to the optimal protocol periodically. The time interval between two speed changes should be long enough so that the subject is able to change the speed. Also, the proposed method is such that, limited attention for control is needed and the controller is not always active.