Tools for quantifying teleoperation system performance and stability when communication delays are present are provided A general multivariable system architecture is utilized which includes all four-types of data transmission between master and slave: force and velocity in both directions It is shown that a proper use of an four channels is of critical importance in achieving high performance telepresence in the sense of accurate transmission of task impedances to the operator It is also shown that transparency and robust stability (passivity) are conflicting design goals in teleoperation systems The analysis is illustrated by comparing transparency and stability in two common architectures, as well as a recent passivated approach and a new transparency-optimized architecture, using simplified one-degree-of-freedom examples >

Stability and transparency in bilateral teleoperation

We survey progress over the past 25 years in the development of microscale devices for pumping fluids. We attempt to provide both a reference for micropump researchers and a resource for those outside the field who wish to identify the best micropump for a particular application. Reciprocating displacement micropumps have been the subject of extensive research in both academia and the private sector and have been produced with a wide range of actuators, valve configurations and materials. Aperiodic displacement micropumps based on mechanisms such as localized phase change have been shown to be suitable for specialized applications. Electroosmotic micropumps exhibit favorable scaling and are promising for a variety of applications requiring high flow rates and pressures. Dynamic micropumps based on electrohydrodynamic and magnetohydrodynamic effects have also been developed. Much progress has been made, but with micropumps suitable for important applications still not available, this remains a fertile area for future research.

https://microfluidics.stanford.edu/Publications/Micropumps_Cooling/Laser%20Review%20of%20Micropumps%20in%20JMM.pdf

A review of micropumps

Bilateral teleoperation: An historical survey

A system for performing minimally invasive cardiac procedures. The system includes a pair of surgical instruments that are coupled to a pair of robotic arms. The instruments have end effectors that can be manipulated to hold and suture tissue. The robotic arms are coupled to a pair of master handles by a controller. The handles can be moved by the surgeon to produce a corresponding movement of the end effectors. The movement of the handles is scaled so that the end effectors have a corresponding movement that is different, typically smaller, than the movement performed by the hands of the surgeon. The scale factor is adjustable so that the surgeon can control the resolution of the end effector movement. The movement of the end effector can be controlled by an input button, so that the end effector only moves when the button is depressed by the surgeon. The input button allows the surgeon to adjust the position of the handles without moving the end effector, so that the handles can be moved to a more comfortable position. The system may also have a robotically controlled endoscope which allows the surgeon to remotely view the surgical site. A cardiac procedure can be performed by making small incisions in the patient's skin and inserting the instruments and endoscope into the patient. The surgeon manipulates the handles and moves the end effectors to perform a cardiac procedure such as a coronary artery bypass graft.

Method and apparatus for performing minimally invasive cardiac procedures

Reports the completion of four fundamental fluidic operations considered essential to build digital microfluidic circuits, which can be used for lab-on-a-chip or micro total analysis system (/spl mu/TAS): 1) creating, 2) transporting, 3) cutting, and 4) merging liquid droplets, all by electrowetting, i.e., controlling the wetting property of the surface through electric potential. The surface used in this report is, more specifically, an electrode covered with dielectrics, hence, called electrowetting-on-dielectric (EWOD). All the fluidic movement is confined between two plates, which we call parallel-plate channel, rather than through closed channels or on open surfaces. While transporting and merging droplets are easily verified, we discover that there exists a design criterion for a given set of materials beyond which the droplet simply cannot be cut by EWOD mechanism. The condition for successful cutting is theoretically analyzed by examining the channel gap, the droplet size and the degree of contact angle change by electrowetting on dielectric (EWOD). A series of experiments is run and verifies the criterion.

Creating, transporting, cutting, and merging liquid droplets by electrowetting-based actuation for digital microfluidic circuits

This work examines electrical damping as a means for improving haptic display performance. Specifically, electrical damping, like its mechanical counterpart, can significantly reduce the occurrences of limit cycle oscillations at high impedance boundaries in virtual environments. Furthermore, electrical damping has a number of advantages including its simplicity of design and the ease at which it can be made frequency dependent so that it does not adversely affect a device's low impedance range. This work examines the theoretical behavior and practical application of frequency dependent electrical damping as it applies to haptic displays. Data is presented illustrating a significant increase in the range of virtual wall behaviors that a one degree-of-freedom device is capable of displaying when electrical damping is added.

/pdf/increasing-the-impedance-range-of-a-haptic-display-by-adding-1t10g622xc.pdf

Increasing the impedance range of a haptic display by adding electrical damping

A passive wrist, of fixed design, can be programmed to execute a wide range of useful control laws. Considered in particular are wrists whose actuators are unpowered hydraulic cylinders, the ports of which are coupled to one another via variable-conductance constrictions. The wrist is programmed by selection of these conductances, much as an analog computer is programmed. The range of control laws such a device can compute is characterized mathematically. >

http://www.ambarish.com/paper/Goswami_1990_ICRA_PassiveRobotics.pdf

Passive robotics: an exploration of mechanical computation

The state-of-the-art in intelligent assist devices (IADs) is reviewed. IADs are computer-controlled tools that enable production workers to lift, move and position payloads quickly, accurately, and safely. Several examples of industrial applications are given, illustrating typical configurations and functionality, including strength amplification and virtual surfaces. The concept of human intent sensing is introduced and discussed, as are IAD safety and control considerations.

/pdf/intelligent-assist-devices-in-industrial-applications-a-ek8et0ulf4.pdf

Intelligent assist devices in industrial applications: a review

We discuss the design and performance of a new haptic surface capable of controlling shear force on a bare finger. At the heart of the ShiverPaD is the TPaD variable friction device. It modulates the friction of a glass surface by using 39 kHz out-of-plane vibrations to reduce friction. To generate shear forces, the TPaD is oscillated in-plane (i.e., “shivered”) while alternating between low and high friction within each cycle. In previous research, the ShiverPaD produced shear forces using in-plane vibrations below 100 Hz. In this research, we develop a new ShiverPaD that produces force using 854 Hz vibrations, where human sensitivity to vibration is diminished. The new device is used to display a virtual toggle switch and a variety of virtual edges. A human subject study is conducted to demonstrate that users can easily trace virtual edges displayed on the surface of the ShiverPaD.

/pdf/shiverpad-a-glass-haptic-surface-that-produces-shear-force-1da0yv9302.pdf

J.E. Colgate

Papers

Increasing the impedance range of a haptic display by adding electrical damping

Passive robotics: an exploration of mechanical computation

Intelligent assist devices in industrial applications: a review

ShiverPaD: A Glass Haptic Surface That Produces Shear Force on a Bare Finger

Modelling of a hydraulic engine mount focusing on response to sinusoidal and composite excitations