ECE 495 Senior Design

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Project Overview

A teleoperated laparoscopic robot is shown in Figure 1.  Each group is requested to design and build a working prototype of a new, low cost implementation of such a system.

The main components of the design are shown above.  The systems should operate autonomously and manually via position commands from the master.  In manual mode, the user will move the master to a position and the control system will measure this position and force the robot to an equivalent position. In this way the robot will follow the motions of the master.  In autonomous mode, a series of position commands will be issued to the robot via a list, eg a text file or a vector variable.

Evaluation of Design

You will specify, in your “Specifications” document, what you are building and your maximum possible point value.  The final design and prototype scores will reflect how well you achieve your specifications on a scale factor from 0 to 1 (0-100%).  The final score will be multiplied by the scale factor to get your final design and prototype demonstration score. For example if you target 85 points and get a 90% score on the prototype evaluation then your total score is 85*0.9 =76.5 points. There are four components in the final grade that we be subject
Design Proposal (10% of overall grade)
Prototype and Demonstration (25% of overall grade)
Design Concept and Design Proposal on Final Report (~5% of overall grade)
You will describe in your “Specifications” how your working prototype will be evaluated.

Current company products that can be used in the design

Technologies

As your group develops technologies for your design or prototype you may either keep these ideas as a "Trade Secret" or "Patent" the ideas, share with the other teams, and get a small "payment" (1 point towards your final project Prototype Demonstration grade).

Q: Are we able to patent anything that we find such as web pages with information and designs or just things that we design or create?
A: If you find or design "something" that represents a unique contribution to advance the robot design project then you can submit for a class patent. I will be fairly liberal with the source of the information but would have to see that it represents a significant contribution towards advancing the work of the class and it would have to not be obvious to the other groups. If you have something send it to me and I will decide.

Here are the patents that are availble for your use.

1. Group 9 has patented use of an inkjet printer mechanism for linear motion axis.
Due to the limited availability of affordable, off-the-shelf linear actuators which could provide a significant range of motion, an alternative was developed utilizing hardware found currently in inexpensive DeskJet or inkjet printers.  This “patented” design makes use of the guide and motor of modern inkjet printers equipped with encoder strips, providing a high-resolution linear motion design that offers approximately 10 inches of linear travel at high-speed and with enough force for many applications that might be incurred during the prototyping of the laparoscopic robot.

The linear motion device requires a “donor” inkjet printer of modern vintage.  Specifically, printers which have been found to work well are inexpensive HP inkjet printers including the 5000 series and the 3900 series, although other brands and models may work as well.  The reason for the requirement of a modern printer is the method of determining position: modern printers make use of a regular DC motor with a plastic encoder strip and an optical encoder head (optical interrupter), while older models more than likely make use of a stepper motor.  Though the stepper motor could be made to work, the printer models with DC motors and encoder strips can be more easily fashioned into linear motion devices, and will therefore be the discussion of this “patent”.  A figure of a printer with an encoder strip is shown below.

Image courtesy of dsnimg.dell.com

DISASSEMBLY
After unplugging the printer and removing the cover, determine whether the motor, belt, shaft, print carriage, and encoder strip (all shown in the figure below) are all attached to a single, removable arm or assembly.  If so, remove this assembly and disconnect any wires or ribbon cables running elsewhere inside the printer.  If all of these items are not attached to a single assembly, modification might be required in order to construct an adequate base to keep all of these parts aligned as they would have been inside the printer.  HP 3900-series printers are known to have this assembly be removable as one piece, though doing so requires a Torx size T10 driver.

Image from everprint.com

HACKING AND REASSEMBLY

After the assembly is removed, the print carriage must be disassembled in order to access the optical encoder reader (optical interrupter).  This part is recognizable because it will likely be the only piece surrounding the encoder strip.  Once the optical reader can be accessed, use part numbers located on the reader to find its data sheets.  Typically, there will be six pins, including a power and ground for the LED which produces the optical signal, a power and ground for the optical receiver on the reader, and A and B outputs.  A data sheet will help determine which of these pins is which, although visual inspection might also prove to be helpful, at least in the determination of ground pins.  Solder wire connections to each of these pins and wire them to the corresponding encoder inputs for the Quanser board.  Also solder connections for the DC motor, making sure to get the polarity correct for the intended direction of movement.  An example of a typical encoder as it would be wired to the Q4 board is shown below:

Agilent HEDS-9710/HEDS-9711 Bottom-Up View to Q4 Encoder Pins
(Typical HP Optical Encoder Reader)

2. Group 1 has patented this amplifier. To build an amplifier, a combination of a Fairchild 741CN operational amplifier, a TIP30 PNP transistor, and a TIP31 NPN transistor will be used. The following diagram of a push-pull transistor configuration with an operational amplifier will be used, with the operational amplifier functioning with a gain of 1 configured as a voltage follower:

To get the supply voltages +V and -V, use the Agilent E3648A DC power supply. Set each channel to output V. (The transistors can handle 0-12V in either direction, so set V depending on how much current is needed. The servos run optimally with V=9.) Tie the negative terminal on output 1 to the positive terminal on output 2 and make this point the reference ground for the rest of the circuit. (The two channels are not tied together inside the power supply, so this is safe to do and will not result in a short-circuit within the supply.) This ground should also be tied to the ground on the Q4 board. With the two outputs tied together, the positive terminal on Output 1 becomes the +6V and the negative terminal on Output 2 becomes the -6V supply.
The resulting circuit can amplify current enough to power the servo motors.

3. Group 9 has patented uses of the Joystick Simulink Block. In the Simulink library, under Quanser Toolbox under Devices under Windows, there is a function block named “Windows Game Controller”. This block can be seen below.

The outputs include x, y, z, Rx, Ry, Rz, sliders, povs, and buttons. Corresponding to our joystick, x and y axes are yaw and pitch, while the roll is Rz. The throttle is one of the sliders, the point of view stick is connected to the pov, and the 12 buttons are connected to buttons. The x and Rz axes are not inverted while the y and slide are inverted. The range of x, y, and Rz are from -1 to 1. The range of the slide and button are from 0 to 1. The range of the point of view stick is from 0 to 5.5.

4. Instructor: The laparoscopic tool can be separated into two parts.

Team Webpages Fall 2009

Evaluation of Prototypes (pdf)

Haptic Devices

Butterfly Haptics (http://butterflyhaptics.com)
SIMENDO Laparoscopic Simulators (http://www.simendo.nl/index.php)

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