BÁO CÁO THỰC TẬP TỐT NGHIỆP, We have leant about robotic arm intheory and applied to create the real product
COVER PAGE Under the supervision and guidance of Assoc. Prof Phan Bui Khoi at Hanoi university of Science and Technology for 4 months We have leant about robotic arm in theory and applied to create the real product
Students: Le Xuan Tu and Pham Van Hai Position: Student of Hanoi university of Science and Technology Class: Mechatronics – Advanced program – K56 Tu’s phone number : +84985799987 – ID 20110735 Hai’s phone number: +841659015834 – ID 20110272 Dates: January 2016 – April 2016
We write this report when we are going to complete our final thesis. After 4 months we had improved our skills as programming , drawing and simulating which are essential to do our final thesis and useful for us to find a suitable after that. This report covers the method that is used to transport blood in the hospital and how this method can be greatly improved with the use of the robotic sorting system. The report details the entire method of how the robot was designed, assembled, programmed, and
interfaced with software and hardware. Also how the infrared sensor was coded and how the motors were synchronized to go to the necessary position.
CHAPTER 1: OVERVIEW ON ROBOTIC ARM 1. A brief history of medical robot In 1985 a robot, The PUMA 560, was used to place a needle for a brain biopsy using CT guidance. Three years later the same machine was used to perform a transurethral resection.
Figure 1: PUMA 560 In 1987 robotics was used in the first Laparoscopic surgercy, a cholescytecotomy In 1988, The PROBOT, developed at Imperial College London, was used to perform prostatic surgery.
Figure 2: PROBOT The ROBODOC from Integrated Surgical Systems was introduced in 1992 to mill out precise fittings in the femur for hip replacement
Figure 3: ROBOTDOC
2. Research motivation
Because the advantage is that robot-assisted surgery gives the surgeon better control over the instruments and a better view, surgeons don't have to stand all of the time during the surgery and do not get tired as quickly. Also, robots do not make the same mistakes that humans can make. Robots are extremely more exact, and they do not move by accident during the surgery. This could also make patients feel less worried before surgery. Finally, we want the life become better, especially for people health. 3. Objectives
The purpose of the project is to design a robotic sorting system for use in the medical industry. This robot will be programmed to go through a routine to locate blood samples, in test tubes, and transport them into their desired location. The robot will consist of a fixed base plate, a rotating joint at gripper, a link robot arm and rotating base. Fixed on the end of the arm will be an infrared sensor and a gripper to pick up the test samples.
CHAPTER 2: DESIGNING, MACHINING AND PROGRAMMING 1. Designing
Figure 4: 3D model
Figure 5: Fixed base and rotating joint
Figure 6: The first link
Figure 7: Rotating joint and gripper
Figure 8: Servo motor –Mg995 2. Machining
The parts of product
3. Programming 3.1.
PIC Microcontroller With the aid of a microcontroller the robot is able to have intelligence to complete programmed tasks. The microcontroller can reduce product sizes, ease implications and allow the development of intelligent computer products. This is why a printed circuit board is necessary to minimize the microcontroller since only part of its development board is used. The 40-pin PIC that is used in robot design is the 16F877 embedded chip. This chip has all necessary capabilities to provided analog to digital conversation, so the sensors can send the precise pulse wave to reach of the motors to maneuver the robot arm. The port A analog input and output pins RA0 are used for the sensor. This sensor is used to detect if there are any obstacles in front of it. Once the sensor detects a test tube the gripper hand will grip both sides of the tube and bring it back to the desired bin.
Figure 9: PIC 16F886 pin out 3.2.
In order to connect a microcontroller to a serial port on a PC computer (or, in this case, the robot arm through the SSC-32 controller) it is necessary to adjust the level of the signals so communication can take place. The signal level on a PC is – 10 V for logic one, and +10 V for logic zero. Since the signal level on the microcontroller is +5 V for logic one, and 0 V for logic zero, we need an intermediary stage that will convert the levels. One chip specially designed for this task is MAX232. This chip receives signals from -10 to +10 V and converts them into 0 and +5 V. We installed this chip onto a board with a series of capacitors. See appendices for circuit diagram.
Figure 10: Constructed Converter Servo Motor A servomechanism is a device used for control by using feedback. A servo is typically electrical in nature, and is employed in many RC vehicles such as boats and cars. Specifically, we are using pulse-proportional servos, which use a signal that is easy to receive and transmit. The signal that the servo receives is 0.9 – 2.1 milliseconds in length, and is repeated every 20 milliseconds. The servomotor positions itself based on the width of the incoming pulse. Most servomotors have up to 180 degrees of rotation, which is considered to be about 90 degrees higher than most RC-based applications. The position of the servos is based in general on absolute positions resulting from pulse widths. A position value of 2500 is a 2.50 millisecond pulse. The ratio of positioning is 0.09 degrees per 1 unit, for a total of 180 degrees per 2000 units. The terms pulse width and position can be used interchangeably. The following figure illustrates the positioning of a servomotor:
Figure 11: Servomotor Pulse Diagram 3.4.
PIC16 RC Servo controller – PSC16A The PSC16A is an integrated circuit board that controls the servomotors on the robot arm. It mounts on the project board directly behind the robot arm itself. Each servomotor is attached (first we ensured that the wires were long enough) to its respective set of pins (0 through 5 were used in this case).
Figure 12: PSC16A Board
Due to its level of complexity, the PSC16A is more appropriately viewed as a “black box” unit that simply controls the servos. A detailed circuit diagram is included in the appendices 3.5.
IRPD Sensor To allow the robot arm to detect the presence of an object at a specific location, we used an Infrared Proximity Detector (IRPD) with a suitable range. The IRPD employs a Panasonic PNA4602M IR sensor accompanied by two LEDs. The module itself has several amplifiers and filters. The detector itself has what is known as a modulated carrier, which allows for the elimination of excess sight (such as responding to sunlight). The sensitivity of the LEDs is adjustable, and the sight of the sensor includes the detection of objects on the left, right and completely in the center. The information is then digitally sent to a receiving microcontroller, which is coded to either ignore the location if a test tube is not present, or complete a subroutine, which removes the tube if present.
Figure 13: IRPD Sensor
4. Software 4.1. TOROBOT RIOS
(TOROBOT Robotic Arm Interactive Operating System) software (for use with the PIC16RC controller) is used to test inputs and outputs, and to generally configure the robotic arm (in particular the labeling and motion of the servomotors). After each servomotor has been “plugged in” to a specific channel on the PIC16RC board, the user is ready to begin the process. An image of the main screen is displayed below:
Figure 14: TOROBOT RIOS interface 4.2.
TTY The functionality of the code (to be compiled in C) was tested using TTY, which is essentially a text-based programmer, used directly through the serial port on the PIC16RC board. By typing lines of code in directly, the user can set the positions on the arm. This is a lot quicker than recoding and recompiling in C each and every time you want to make an adjustment. Also, commands are typed very intuitively.
The goal of this project was to construct a model robot that could detect and transport blood samples in the medical industry. After starting out with a vague idea of how to program a microcontroller and formulating a plan to achieve the created goal of the project, the robot kit was received and shortly after the robot was created. The infrared sensor was attached to the gripper for the purpose of locating if there is a sample ready for delivery or not. The robots motors and sensors were then connected to the PIC microcontroller board so they could be programmed to do the task at hand. The end result of the project was a small prototype that was capable of sensing objects and transporting them to a desired location. This robotic sorting system provides a more efficient and effective means
of locating and transporting blood samples. It will allow lab technicians to be trained into different areas and shorten wait times in hospitals.