Kevin Tuer

The effect of time delays on tele-haptics

Information technology has reached a limit in what can be done in training and doing remote tasks with only sight and sound. The next critical step is to add the sense of touch over network connections, otherwise known as tele-haptics. In this paper, an experimental demonstration involving a simple identification task has been developed, using a custom two degree-of-freedom haptic interface. The experiment shows quantitatively that haptics can be employed to greatly enhance user performance but the addition of simulated network time delay and sensor noise quickly degrades performance. It is demonstrated that time-delay compensation techniques can aid in situations where the time-delay and sensor noise make the equipment unusable. In addition, another experiment demonstrating tele-haptics using two MPB Freedom 6S haptic devices is discussed. Key issues in the implementation of such an experiment are presented and a description of the results is given.

Haptic overlay device for flat panel touch displays

Summary form only given. In an effort to present users with an increasing amount of information, many industries including automotive and aerospace are adopting flat panel touch displays as a user interface. These interfaces are becoming popular due to their reconfigurability so that control and display functions can be embedded in multiple layers or menus. However, one of the disadvantages of this approach is the need for the user to constantly look at the display to operate it. In this paper, a haptic overlay device (HOD) is used to address user distraction issues. The HOD is comprised of a conventional off the shelf touch screen display, a custom haptic device, electronics and software. The haptic device has been designed to fit over top of the touch screen. With the HOD, a user is able to feel items, such as buttons and sliders, on the screen.

Regulation of a lumped parameter cantilever beam via internal resonance using nonlinear coupling enhancement

In this article, we propose a nonlinear control law to enhance the performance of internal resonance (IR) controllers used for the regulation of vibration in flexible structures. Active IR controllers are composed of sliding or rotational actuators attached to the flexible structure, introducing dynamic nonlinearities into the system. The IR control strategy forces a state of internal resonance at which the transfer of oscillatory energy from the structure to the controller mechanism takes place. Once this energy is transferred to the controller it is dissipated via velocity feedback. These controllers are unconventional since they function at a state of resonance. The resonance condition is established upon tuning the controller natural frequency (using position feedback) to twice the fundamental beam frequency which causes the oscillatory energy to be transferred to the controller via the nonlinear coupling terms where it is dissipated. However, the rate of dissipation is limited since the controllers have a limited “critical” damping coefficient.In this article we study the effect of the IR controller on a simplified lumped mass model representing a cantilever beam. The nonlinear enhancement technique proposed in this article improves the performance of this type of regulatory by increasing the nonlinear coupling effect which is responsible for the energy transfer, and hence, speeding the rate of vibration suppression.

Towards a generalized regulation scheme for oscillatory systems via coupling effects

The vibration suppression laws presented in this work utilize an energy transfer phenomena that is evident in some linearly and nonlinearly coupled systems. The first iteration of the formulation is presented in this paper. These control laws are unique in that the states approach the operating point on the order of a cosine function, the nonlinear control law renders a unidirectional control input, and the intuition associated with the energy transfer analogy aids the controller design. >

A new design paradigm for the rapid development of haptic and telehaptic applications

The concept of modern day haptics - providing the simulated sense of touch - has been a topic of research since the early 1980s. Since then, a number of researchers and companies have striven to drive haptic applications into the mainstream. One of the primary barriers to the development of commercially viable application is the disconnection between the application visionaries, which tend not to be haptics experts, and the available development tools. In this paper, we discuss a new paradigm for haptic and telehaptic application development The basis of this new paradigm is a drag and drop, block diagram based design environment Thus, the application developers, which tend to have industry specific expertise but rarely haptic knowledge, are able to independently prototype haptic and telehaptic applications with minimal software coding. This new paradigm promises to vastly improve prototyping efficiency and enable a much larger group of application developers

Regulation of a Two-Degree-of-Freedom Structure Using Internal Resonance

In this paper, we present a first attempt at using an energy based control technique to regulate the oscillations of a flexible joint, flexible arm device, through computer simulation. This technique takes advantage of the Internal Resonance (IR) phenomenon. The plant is governed by two coupled linear differential equations. The control scheme is implemented by introducing two software based controllers which are coupled dynamically with the plant through a nonlinear feedback control law. At Internal Resonance, the nonlinear coupling generates an energy link between the plant and the controllers. Thus, energy is transferred from the plant to the controllers where two active damping mechanisms subsequently dissipate it. Here the response of the structure is regulated with a single input torque applied to one plant coordinate. The theoretical analysis is based on the two-variable expansion perturbation method. Thereafter, the analytical findings are verified numerically. Simulation results indicate that the IR control strategy is able to effectively quench the oscillations of the plant.

Conducting a real-time remote handshake with haptics

Summary form only given. A demonstration has been developed that illustrates a bilateral telehaptics platform to enable a local user and a remote user to shake hands in real time over a telecommunications network. The platform has been developed around an off-the-shelf six DOF haptic manipulator and a real time operating system. Only the first three DOF of the device are enabled with haptics. The demonstration shows two devices connected in a bilateral telehaptic configuration on a local network with a network traffic simulator in between the two devices.

Implementation issues for bilateral tele-mentoring applications

Recent advances in the area of tele-haptics - the ability to transmit the sense of touch over communications channels - has enabled the implementation of tele-mentoring of tasks where a remote expert user guides a local student by literally holding his/her hand via a network connection. A demonstration of tele-haptics was successfully conducted between Geneva and Ottawa in October, 2003 using a mannequin in lieu of a virtual environment for a medical training simulation. In this paper, the results of that demonstration are extended to include a virtual environment. The task is that of guiding a user through a haptic simulation of a bifurcation of an artery in a medical training simulator. Two commercial six degree of freedom haptic devices (three degrees actuated) are employed in this experimental setup. It is demonstrated that, in the presence of time delays, this simple task is rendered unusable due to the appearance of instability. A time-delay compensation technique is used to restore stability. Two implementation issues have been found to greatly impact both stability and performance. The first issue is that of the sampling period used by the haptic devices at both the local and remote locations. The second is that of slight differences in the sampling times of the controllers at both local and remote haptic devices, which ultimately impacts the synchronization of the controllers at the two locations. The impact of these two implementation issues will be studied for this particular application through experimental verification.

Vibration suppression of a single flexible link using a linear modal coupling paradigm

Unique phenomena that can arise in linear and nonlinear systems that are dynamically and/or statically coupled have been utilised for vibration suppression. In the linear case, static coupling is established between the oscillatory modes of a plant with a single input and a series of second order controllers. The controlled system is characterised by a plant response that approaches the desired state at the rate of a cosine function. In this investigation the single-degree-of freedom coupling control theory is extended to suppress disturbance induced oscillations of a single flexible link. The suppression action is achieved using the hybrid control method which was developed to supply the suppression action, especially for the multidegree-of freedom case. The resulting control algorithm is implemented experimentally.<<ETX>>

Ascertaining the stability of internal-resonance-based vibration suppression laws

Recently,there has been research conducted examining the feasibility ofusing a phenomena that arises in some dynamically nonlinear systemsas a paradigm in the formulation of generalised vibration suppressionlaws. The first stage of the research involved the developmentof canonical control laws for a class of single-degree-of-freedom(SDOF) systems. This paper focuses on ascertaining the stabilityof the closed loop system using two such canonical control laws.