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I8    USA University of Hawaii
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Projects
Compact Laparoscopic Surgery Robot System
We have developed a manipulator for laparoscopic surgery. Its novel features are its compact size and low weight, so that it is easy to set up and use without occupying any floor space or obstructing access to the abdomen from any direction.

Characteristics of the current Prototypes:

  • Easy to set up, portability, simple sterilization by autoclave, reduced cost, increased safety due to low inertia
 
Principle of Compact Laparoscopic Surgery Robot
Small modular robots clamped above abdomen of patient
System Schematic of Compact Laparoscopic Surgery Robot
Teleoperation masters and low-level motor controllers coordinated by high-level controller on PC

Components of the Prototype:

  • Teleoperation Masters
  • Voice Command
  • Control Software
  • Motor Controller
  • Feedback Sensors
  • Endoscope Manipulator
  • Instrument Manipulators
  • Surgical Instruments
  • Video Feedback
 
Design of Manipulator and Surgical Tools
Modular endoscope and instrument manipulators used together for surgical models
Compact Laparoscopic Surgery Instrument Manipulator
 
 
Endoscope manipulator and two instrument manipulators on frame clamped to table
Teleoperation Master Console (Phantom Haptic Devices):
Sensors on linkage measure surgeon hand movements used to control surgical instrument manipulators in real time.
 
Magnetic Levitation for Haptic Interaction
Magnetic levitation systems are well suited for haptic and other human-machine interaction as they are highly backdrivable, contain only a single moving part, and are not subject to the friction, hysteresis and cogging present in motors, gear reductions, and linkage mechanisms. Furthermore, magnetic levitation devices have a high potential for precise positioning, fast dynamic responses, and very high achievable impedance ranges. The combination of these properties enables physical interaction with simulated environments with a degree of realism and detail unattainable by other means of actuation. Haptic interaction using magnetic levitation provides a particularly rich medium for human-computer interaction, distinct from graphical computer interfaces, in simulation application areas such as medical training and vehicle operation.

We are currently developing two magnetic levitation devices: A hemispherical Lorentz force device for handheld, tool-based haptic interaction, with a novel design for twice the translation and over three times the rotation range of earlier similar devices, and a modular and scalable planar electromagnetic repulsion levitation device for interactive vehicle simulations.

Hemispherical Lorentz Magnetic Levitation Device Design:

The levitated portion of this device or flotor consists of a thin hemispherical shell with 6 large coils wound around the outside surface in 2 layers and a manipulation handle attached at the center by 3 struts. Currents in the 6 coils interact with magnetic fields from permanent NdFeb magnets on the fixed statorassembly to generate 3D forces and torques for levitation and haptic feedback. An optical motion tracking subsystem provides position sensing for closed-loop control. The handle has a motion range of 60 degrees in rotation and 50 mm in translation along any direction.
 
 
Levitating bowl with 2-layer straight wire coil pairs
Handle for haptic interaction
Vertical step response results
The motion step response under simple PD control is currently underdamped due to the 1200 g levitated mass (reducible to 400-500 g by using aluminum coils), and the limited resolution and update rate of the motion tracking sensor.
 
Planar Repulsion Magnetic Levitation Device Design:

The base of this magnetic leviation device contains an array of cylindrical electromagnet coils which generate repulsive forces and torques to levitate and manipulate a platform containing 4 disk magnets. The basic module shown will be able to scale to larger area coil arrays with multiple levitated platforms to support a human user and simulate arbitrary vehicles, as shown below.
 
 
   
 
Linkage for Locomotor Rehabilitation
We are developing a prototype linkage for use as an ankle-foot orthosis to prevent the foot-drop condition. The linkage is attached to the calf and foot of the patient and passively couples together the motion of the knee and ankle during locomotion. As the knee is bent at the beginning of the stride phase of a walking gait, a curved bar contacts the back of the thigh and the linkage mechanism produces a force to assist the flexion of the ankle at the initiation of the stride phase. An initial wearable prototype has been fabricated and is ready for initial testing on test subjects to demonstrate the feasibility of the concept and refine the design of the mechanism.
 
 
WWW Teleoperation Interface for Instructional Robot Arm
A Microbot Teachmover II has recently been acquired by the laboratory to be used for instructional purposes. We have developed an Internet robot teleoperation system for use in education. In order to facilitate the robot teleoperation for distant users, our Internet robot teleoperation system as been developed based on Skype Internet telephony protocols. By using the Skype API, the video, audio and data transmission are readily programmed and realized.

This robot teleoperation system consists of a local robot server and distant clients. The server directly controls the robot motion according to the commands from a distant client, while the client provides the operation interface to users for distant robot operation.
 
Microbot Teachmover II
Client
Server
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Human-Robot Interaction Laboratory

Work in the laboratory was begun in spring 2005 and the research here generally deals with topics including robot-assisted surgery, haptics, and interactive physical simulations.  The common element in this work is that direct physical interaction is involved between human users and robotic devices.

Active Projects:

  • Compact Teleoperated Robot System for Minimally Invasive Surgery
  • Magnetic Levitation Systems for Human Interaction

Inactive Projects:

  • Linkage for Locomotor Rehabilitation
  • Active Stabilization Support Frame for Surgical Instruments
    Instructional Robot Interface

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