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

A haptic interface device, said device comprising a substrate, a first conducting layer deposited on the substrate, with the first conducting layer being patterned to provide a first axis of individually-addressable conductive electrodes, a first insulating layer deposited on the first conducting layer, with the insulating layer having a uniform thickness, a second conducting layer deposited on the first insulating layer, with the second conducting layer being patterned to provide a second axis of individually-addressable conductive electrodes, and a dielectric layer deposited on the second conducting layer, with the dielectric layer having a uniform thickness and hardness and being scratch resistant.

Materials and structures for haptic displays with simultaneous sensing and actuation

Cobots assist humans by mechanically guiding motion along software-defined paths or surfaces. Cobot design has been extensively studied previously. This paper reports the first systematic experimental study of motion guidance with a cobot. We investigated the movements of seven operators with the Scooter cobot in representative environments. Analysis of the force exerted by the operators and the trajectories reveals significant differences between guided movements (GM) and free movements (FM). While FM requires learning for each novel task, GM is optimal from the first trial: Less effort is required to move in GM than in FM, Movements in GM are faster, smoother, and require less back and forth correction than in FM. These advantages demonstrate the strength of the Cobol concept. The results further suggest that operators guided by the Scooter can handle objects in a more "open-loop" way than with a dumb trolley, and so perform faster and concentrate on other aspects of the manipulation task, potentially resulting in increased productivity and fewer injuries.

Motion guidance experiments with Scooter Cobot

Robotic micromanipulator for ophthalmic surgery

A novel method based on deformable length of elastic element control (DLEEC) to realize the stiffness display for perception of virtual soft object is proposed, and the stiffness display interface device has been developed and is presented. The stiffness display interface device is composed of a thin elastic beam and an actuator to adjust the length of the beam. The deformation of the beam under a force is proportional to the third power of the beam length. By controlling the beam length, the stiffness display device can reproduce the stiffness of the virtual object from very soft to hard, so that the human fingertip can feel it as if he directly touches with the virtual object by interacting with the device. A real time position control algorithm is employed to guarantee the real time stiffness display.

/pdf/real-time-stiffness-display-interface-device-for-perception-3yiya0db00.pdf

Real time stiffness display interface device for perception of virtual soft object

We built a high fidelity, low mass, linear haptic display, with a peak force output of 8.5 Newtons, continuous force output of 1.3 Newtons, range of motion of approximately 15 millimeters, sensing resolution of 0.5 microns, and a -3 dB bandwidth of approximately 550 Hz. By having low apparent mass of approximately 5 grams, we can realistically render linear switches, which themselves have a moving mass of only a few grams. This device utilizes a low inertia rotary motor, but over only a limited range of motion, allowing it to be driven without commutation. We constructed a linear, current controlled amplifier to drive the system. Additionally, the motor windings allow us to use electrical damping to add physical damping to the system to improve its performance.

/pdf/design-and-performance-of-a-high-fidelity-low-mass-linear-5bj3gjw8q4.pdf

J.E. Colgate

Papers

Materials and structures for haptic displays with simultaneous sensing and actuation

Motion guidance experiments with Scooter Cobot

Robotic micromanipulator for ophthalmic surgery

Real time stiffness display interface device for perception of virtual soft object

Design and performance of a high fidelity, low mass, linear haptic display