Design of Haptic Interface Controller under Noise Uncertainty and Delay Condition

Haptic interfaces are becoming more commonplace in virtual environment and teleoperation systems. There is a growing need to not only continue to improve hardware platforms and rendering algorithms, but evaluate human performance with haptic interfaces. This review summarizes two recent studies inspired by perception problems in using haptic interfaces to interact with virtual environments. The first study evaluated perceived quality of virtual haptic textures and discovered several types of perceived instability and their sources. We found that the buzzing type of perceived instability was most likely due to the mechanical resonance of the haptic interface hardware, and the aliveness type of perceived instability due to our inability to sense the slight movements of our hands in free space. The second study focused on the motor strategy employed during interaction with a virtual surface via a force-feedback haptic interface. We found that users tended to maintain a constant penetration force into a virtual surface when interacting with the surface. This can result in a reversal in perceived relative surface heights if the taller surface is rendered with a lower stiffness, thereby resulting in an erroneous perception of the virtual environment being rendered. For both studies, possible solutions to improving human perception of virtual and remote objects via hardware and/or software are discussed.

A haptic interface is a device for operators to touch, feel and manipulate virtual environments. It senses the contact forces and gives operators a sensation of interacting with a real physical environment. Force feedback can improve the quality of the haptic feedback control in virtual reality applications. In this paper, a real time haptic interface is developed via control models in the Labview virtual environment, which is a combination of a touch force measurement haptic interface and a vibro-tactile CyberGlove serial haptic interface. The haptic interface is a prototype for real time feedback control on robotic integration of smart censors. This approach is easy to apply on various types of sensors, such as acoustic wave sensors, ultrasound array, etc., which will enhance the ability to communicate between the operators and the virtual environment. The flexiforce sensor and tactile sensor based haptic interface in force feedback systems will improve traditional robot visual sensing systems by a virtual feel.

Haptic interaction in slow virtual environments (VEs) can become unstable due to the phase lag introduced in the control loop by the slow update rate of the VE. Increasing the physical damping and/or limiting the contact stiffness rendered to users can mitigate the destabilizing effect of the low VE update rate. However, large physical damping and compliant virtual contacts decrease the sense of presence in VEs, especially during interaction with rigid virtual objects. To increase the maximum virtual contact stiffness that can be rendered to users without increasing the interface damping, this paper proposes a control strategy based on multirate wave communications between a haptic interface and a VE updated at a slow and fixed rate. The multirate wave communications are shown to be guaranteed passive only if the decrease of the wave sampling rate at the connection between the haptic interface and the VE does not cause aliasing. Therefore, an antialiasing low-pass filter is placed before the wave rate drop in the communications. The passivity condition is verified analytically and numerically for multirate haptic interaction in VEs with various contact stiffnesses and update rates. The transparency of haptic interaction in slow VEs to which users connect via passive multirate wave communications is investigated analytically in the frequency domain. Experiments validate that passive multirate wave communications can render stiffer contact in slow VEs than conventional direct coupling, and illustrate the destabilizing effect of the aliasing caused by the sampling rate drop in the communications.

In this paper, we propose the use of a nonlinear disturbance-observer for estimation of contact forces during haptic interactions. Most commonly used impedance-type haptic interfaces employ open-loop force control under the assumption of pseudostatic interactions. Advanced force control in such interfaces can increase simulation fidelity through improvement of the transparency of the device. However, closed-loop force feedback is limited both due to the bandwidth limitations of force sensing and the associated cost of force sensors required for its implementation. Using a disturbance-observer, we estimate contact forces at the tool tip, then use these estimates for closed-loop control of the haptic interface. Simulation and experimental results, utilizing a custom single degree-of-freedom haptic interface, are presented to demonstrate the efficacy of the proposed disturbance-observer (DO)-based control approach. This approach circumvents the traditional drawbacks of force sensing while exhibiting the advantages of closed-loop force control in haptic devices. Results show that the proposed disturbance-observer can reliably estimate contact forces at the human-robot interface. The DO-based control approach is experimentally shown to improve haptic interface fidelity over a purely open-loop display while maintaining stable and vibration-free interactions between the human user and virtual environment.

Proportional-Integral (PI) and Proportional-Integral-Derivative (PID) controllers are commonly employed in process and Cruise Control Systems (CCS) to control system behaviour. PID controllers have a derivative action to improve transient response and system stability, while PI controllers use proportional and integral actions to minimise steady-state errors. This study explores the performance of both controllers in these applications by designing and implementing them within each system. The methodology involves simulating the systems under different conditions, including variations in setpoints and disturbances, to observe how the controllers manage dynamic behavior. The study assesses both controllers' performance in various scenarios, emphasising their capacity to manage disruptions and preserve stability. The study's objective is to offer a thorough comprehension of the design and performance characteristics of PI and PID controllers in process and CCS, offering insights into their suitability based on specific system requirements and performance goals. The PI controller is found to be the best choice for certain applications due to its simplicity and effectiveness

This book covers all topics relevant for the design of haptic interfaces and teleoperation systems. The book provides the basic knowledge required for understanding more complex approaches and more importantly it introduces all issues that must be considered for designing efficient and safe haptic interfaces. Topics covered in this book provide insight into all relevant components of a haptic system. The reader is guided from understanding the virtual reality concept to the final goal of being able to design haptic interfaces for specific tasks such as nanomanipulation. The introduction chapter positions the haptic interfaces within the virtual reality context. In order to design haptic interfaces that will comply with human capabilities at least basic understanding of human sensors-motor system is required. An overview of this topic is provided in the chapter related to human haptics. The book does not try to introduce the state-of-the-art haptic interface solutions because these tend to change quickly. Only a careful selection of different kinematic configurations is shown to introduce the reader into this field. Mathematical models of virtual environment, collision detection and force rendering topics are strongly interrelated and are described in the next two chapters. The interaction with the virtual environment is simulated with a haptic interface. Impedance and admittance based approaches to haptic robot control are presented. Stability issues of haptic interaction are analyzed in details and solutions are proposed for guaranteeing stable and safe operation. Finally, haptic interaction is extended to teleoperation systems. Virtual fixtures which improve the teleoperation and human-robot cooperation in complex environments are covered next and the last chapter presents nanomanipulation as one specific example of teleoperation.

The speed control of a switch reluctance motor (SRM) using feedback control method with the help of a proportional integral (PI) controller is presented in this paper. The paper proposes the design of a PI controller for a 6/4 SRM under different load conditions. The control mechanism is designed such that the motor runs at half of the rated speed for first few cycles and then attains the rated speed for the remaining cycles. The values of the controller gains Kp, Ki are tuned in such a way that the rated speed is maintained under different operating conditions. MATLAB Simulink is used to illustrate the simulation results for the motor at zero, half and full load conditions. The simulation results are compared and analyzed.

The haptic interface provides the virtual environment for the remote servo manipulator, and it can make the operator feel and manipulate the remote or virtual environment. For arbitrary passive operator (human), the stability not only relates to the parameters of the haptic device and the virtual environment, but also relates to the type of the sampling signal of the system. The passivity conditions for haptic interface systems with position sampling are given in existing works, but the parameters scope for passivity design is very small. In view of this, velocity of the haptic device is used for the sampling signal in this paper, and a wider passive region is derived based on the frequency response of a sampled-data control system. At last, through overall consideration of the bandwidth, damping ratio and passivity requirements, a reasonable design result is given in the paper.

The purpose of evaluation procedures is to achieve both qualitative and quantitative statements on haptic rendering realism and performance. Since a haptic interface provides an interaction between a user and a virtual environment, fidelity of a haptic interface directly affects the performance. To our knowledge, a standard, generic and reusable validation method which comprehensively addresses all the attributes of haptic feedback has not been realized yet. Despite the large number of human factor studies, only few of them have been proposed as well for haptic interface performance measurements. For this reason, we review validation procedures for haptic rendering and propose an evaluation method based on testbeds to obtain a systematic haptic interface assessment. We integrated the approaches of human factor studies into the testbeds to obtain a simple and yet complete measure of human-machine interaction performance. The testbeds were tested on a haptic interface, the IHP of Xitact SA, and performance results are presented. In the testbeds, performance metrics for generic haptic interaction tasks are expressed in terms of information transfer (bits) and sensory thresholds which are indeed device specific benchmark metrics. Thus, the suitability of a haptic interface for a defined task can be verified, device comparisons become possible and the obtained information can be used to identify possible improvements.

This paper presents a comprehensive analysis of the identification and control of a reflow soldering oven, with the primary goal of developing a Proportional-Integral (PI) controller to ensure precise temperature regulation and high-quality solder joints in circuit board manufacturing. The study begins by examining the generic thermal profile of a reflow soldering oven, offering insights into its temperature dynamics and control requirements. A mathematical model of the oven is derived using a first-order transfer function with transport delay, based on system response analysis. This model serves as the basis for designing and tuning the PI controller. The design process involves a systematic approach, including model validation and performance analysis under various operating conditions. The optimization of temperature control focuses on minimizing overshoot, compensating for steady-state errors, and ensuring robust responses to disturbances. Comprehensive simulations are conducted to evaluate the system's performance and stability, taking into account potential disturbances, noise, and time delays. The effectiveness of the developed PI controller is validated through comparisons with a simple Proportional (P) controller, and its accuracy is verified using the pole placement method. The results demonstrate significant improvements in temperature control, highlighting the controller's ability to precisely maintain desired thermal profiles.

The performance levels of human subjects in size identification and size discrimination experiments in both real and virtual environments are presented. The virtual environments are displayed with a PHANToM desktop three degree-of-freedom haptic interface. Results indicate that performance of the size identification and size discrimination tasks in the virtual environment is comparable to that in the real environment, implying that the haptic device does a good job of simulating reality for these tasks. Additionally, performance in the virtual environment was measured at below maximum machine performance levels for two machine parameters. The tabulated scores for the perception tasks in a sub-optimal virtual environment were found to be comparable to that in the real environment, supporting previous claims that haptic interface hardware may be able to convey, for these perceptual tasks, sufficient perceptual information to the user with relatively low levels of machine quality in terms of the following parameters: maximum endpoint force and maximum virtual surface stiffness. Results are comparable to those found for similar experiments conducted with other haptic interface hardware, further supporting this claim. Finally, it was found that varying maximum output force and virtual surface stiffness simultaneously does not have a compounding effect that significantly affects performance for size discrimination tasks.

This paper presents the characterization, and modelling of the volumetric balance equation contributing to the elaboration of Continuous Stirred Tank Heater (CSTH) plant. The conventional Proportional Integral (PI) controller technique is used to control the physical variables such as cold water valve position, and the liquid level in the tank of the CSTH plant. The controller is designed and implemented using Simulink in Matlab to achieve the operational objective of the CSTH process. The response of CSTH with and without PI controller is compared.

Power flow control in double circuit transmission lines is crucial for maintaining system stability and ensuring optimal utilization of resources. This paper proposes a novel approach using a Five Level Unified Power Flow Controller (UPFC) with a Grey Wolf Optimizer (GWO) tuned Proportional-Integral (PI) controller. The Five Level UPFC acts as a flexible and efficient solution, facilitating the concurrent regulation of both active and reactive power flow in transmission lines. By applying the GWO algorithm, the aim is to improve the performance of the UPFC control system through the optimization of the PI controller's parameters. By imitating the natural hunting behaviour of grey wolves, the GWO algorithm achieves exceptional convergence and solution accuracy. The suggested control scheme is implemented and tested on a double circuit transmission line system. The system's effectiveness is evaluated under various operating conditions and compared against alternative control approaches. The findings establish the efficacy of the Five Level UPFC with a GWO-optimized PI controller in effectively regulating power flow and enhancing overall system stability. Furthermore, the proposed approach exhibits excellent robustness against parameter variations, load fluctuations, and system disturbances. The GWO optimization technique ensures optimal tuning of the PI controller, this leads to decreased power losses, enhanced voltage profile, and improved system reliability. Overall, the application of the Five Level UPFC with GWO-tuned PI controller provides an efficient and reliable solution for power flow control in double circuit transmission lines. The suggested method can make a substantial contribution to enhancing the operational efficiency of power systems, this enables the seamless integration of renewable energy sources and the progression of smart grid infrastructures. The circuit is simulated using the MATLAB/SIMULINK software. And the following results from the simulation are presented below

Multifinger haptic interface is the ultimate human haptic interface that would provide natural manipulation and feeling to the tip of each finger, same as the real hand interaction with the real world in daily-life tasks. This chapter introduced the second version of HIRO, including the hardware design, the control algorithm, and the software design including the system architecture, haptic rendering, and practical VR application. The hand with the arm provides a large workspace and reflects exactly the human hand movement as you are looking to your hand and arm in the mirror, with some differences related to hardware limitations and control methods that yet need to be improved. A comprehensive haptic system through demonstration of the future haptic science encyclopedia is presented. The architecture used was a multi-layer network framework that decoupled the haptic from graphic on to separate machines. The architecture maintained the high update rate needed for the haptic servoloop. Also, an accurate collision detection algorithm that considers the shape of human fingertips is developed. A physically based modeling using the finite element method (FEM) combined with an elementary displacement approach proved to ensure stable interaction and realistic forces calculation for a relatively complex deformable model in real time. The approach takes into considerations interaction with multipoint contacts where other approaches failed to achieve such interaction due difficulty in calculating forces at 1 KHz. The FHSE application was demonstration at World Expo 2005. People enjoyed the demonstration, where the majority were satisfied with the system as it provided a unique experience. Finally, combining technologies such as virtual reality and haptic robotics enables us to extend the capabilities and effectiveness of simulators. We anticipate that the proposed system will bring the notice of many researchers to the feasibility of implementing multifinger haptic interfaces. Although, every one agree on the importance of such interface, but many obstacles are still preventing the advancement of this research field. This chapter provided a complete picture on how this could be achieved. The greatest lesson of such project was the collaboration between robotics community and virtual reality community is necessary to achieve a better and comprehensive sophisticated haptic robot. Eventhough , I was the leader of the software development side including the haptic rendering and VR application, I was involved from the beginning in the process of designing the hardware and the control algorithms as well, useful feedback was the result of such collaboration. There are a number of future directions that can apply to this research. First, it is desirable to test the presented architecture in the presence of large delay and apply some techniques to compensate it. Second, develop more robust control algorithm for the arm movements to reflect the exact motion of the human hand, this will make the interface manipulation very natural. Also, make the hardware itself smarter and safer.

In addition to the visual and auditory feedbacks, the force and torque feedbacks will definitely make the virtual environment more immersive. This idea has encouraged the researchers to go through the non-ground-based haptic interfaces containing these capabilities. In this paper, a new ungrounded haptic interface will be developed which can provide real sense of linear and angular momentum in three-dimensional space. Incorporation of a pair of propellers into the haptic interface will make it to continuously produce the desired forces and torques in less than 350 ms up to 15 N and 1 N.m, respectively. To orient the produced forces and torques in the desired and arbitrary directions in the three-dimensional space, these propellers are mounted on a set of sliders and gimbal rings. Due to the simple structure and effortless control of the proposed mechanism, rooted in the developed novelty in the mechanism design, the haptic interface can be more practical for the illusion of complex tasks in the daily uses. In this paper, the detailed design and force analysis of the haptic interface are followed by analytically derived kinematic and dynamic model, verified in MATLAB/Simscape Multibody. Then, the mathematical framework for the proposed controller is addressed, and afterward the robust stability analysis in the presence of structured and unstructured uncertainties is investigated. Eventually, a measuring prototype has been designed and manufactured to experimentally evaluate the performance of the haptic device and proposed control algorithm. The experiments show good performance of the proposed system and controller in the tracking of the various forces and torques on different paths.