MODEL ROBOT SOCCER

 

WEEK 14 (25 - 29 OCT 2010)

Prepare for presentation final year project.

 

WEEK 13 (18 - 22 Oct 2010)

Design the circuit in Proteus

this design by using Proteus software, the input which is sensor we assume the ADC. the microcontroller we use is PIC 16F877A. from the design we use 3 output which is 2 DC motor and 1 servo motor. we use DC motor for movement the robot where the motor at the left side and the right side. servo motor as a suspension for control the rotation the robot. the servo motor move in a degree. this simulation is not equal with the real design. for the real design the motor must have motor driver circuit.

WEEK 12 (11 - 15 Oct 2010)

RC Servos Motor

A "servo" is a generic term used for an automatic control system. It comes from the Latin word "servus" - slave. In practical terms, that means a mechanism that you can set and forget, and which adjusts itself during continued operation through feedback. The word "servo" really means an RC (remote control) servo motor. This is a small box designed for use in hobby airplanes and cars. Inside this box is a complete servo system including: motor, gearbox, feedback device (pot), servo control circuitry, and drive circuit. RC servos normally have 3 wires: +v, ground, control. The control signal is a pulse that occurs at about 50 Hz. The width of the pulse determines the position of the servo motors output. This would be easy to control with a digital controller such as a Basic Stamp. Most will run on 5-6 volts and draw 100-500ma depending on size. The control circuitry to perform good servo of a DC motor is much more complex than the circuitry that controls a stepper motor.

 RC servo controlling

Servo motors are small, compact and quite cheap. The servo motors itself have built in motor, gearbox, position feedback mechanism and controlling electronics. The servo motor can be controlled to move any position just by using simple pulse controlling. 

Figure 2.4: The rotation of servo motor

Servo motors have three wire interfaces for controlling and power supplying. The wires are colored using following color code:

Ø  BLACK     Ground

Ø  WHITE     Control pin

Ø  RED       +4.8V power supply (+5V works well in this)

Controlling of the servo motors is used using pulse controlling. The control pulse is positive going pulse with length of 1 to 2 ms which is repeated about 50-60 times a second. The details can be check in the figure below:

                         ____                               ____      _+4.8V

                        |    |                             |    |                  

                        |    |                             |    |

                    ____|    |_____________________________|    |____  _GND

                        |<-->|

                        1.2 ms

                               |<-------------------------------->|

                                      18-25 ms

Sending 1 ms pulses sets the servo to one end position and sending 2 ms pulses sets it to the other end position. Sending 1.5 ms pulse sets the servo motor to the center position. The controlling scheme is very easy to implement with some electronics.  

RC servos are hobbyist remote control devices servos typically employed in radio-controlled models, where to provide actuation for various mechanical systems such as the steering of a car, the flaps on a plane, or the rudder of a boat.

                                                                                               

Figure 2.6: Small R/C servo mechanism
1.Electric motor
2.Position feedback potentiometer
3.Reduction gear
4. Actuator arm

 RC servos are composed of a DC motor mechanically linked to a potentiometer. Pulse-width modulation (PWM) signals sent to the servo are translated into position commands by electronics inside the servo. When the servo is commanded to rotate, the DC motor is powered until the potentiometer reaches the value corresponding to the commanded position. The servo is controlled by three wires: ground (usually black/orange), power (red) and control (brown/other color). This wiring sequence is not true for all servos, for example the S03NXF Std.

Servo is wired as brown (negative), red (positive) and orange (signal). The servo will move based on the pulses sent over the control wire, which set the angle of the actuator arm. The servo expects a pulse every 20 ms in order to gain correct information about the angle. The width of the servo pulse dictates the range of the servo's angular motion.

 

2.4.1    Driving RC servos

As has already been mentioned, all RC servos have three connections: power (positive), power (ground or negative), and the controlling signal. The interesting part is the control signal. An RC servo motor doesn't just run when we give it power. It's an intelligent device, and we must tell it what we want it to do. We need something that drives the servo with that control signal.

2.4.2    Powering RC Servos

Most servos require a power supply between 4.8V and 6.0V. The higher the voltage, the faster the servo will move and the more torque it will have.

2.4.3    Theory of Driving RC servos

The servo is controlled by a series of pulses, wherein the length of the pulse indicates the position to take.

pulse width	angle	comment
0.6m Sec	-45 degrees	minimum pulse length
1.5m Sec	0 degrees	center position
2.4 mSec	-45 degrees	maximum pulse length

Table 2.1

Increasing the pulse width by 10 µSec results in about a degree of movement on the output shaft.

·         These numbers are nominal, and vary slightly between manufacturers and models. The rate at which these pulses are sent isn't terribly important - only the width of the pulse.

So, the short story is, if we can make a series of electrical pulses, we can rotate the servo shaft through a range of 90 degrees. And that 90 degree range of rotation can open and close the jaw of a skull, move eyeballs left and right, point a finger, or do all sorts of creepy animation.

WEEK 11 (4 - 8 Oct 2010)

Continues design circuit diagram in the Proteus software, code test PCB input and output.

1. To design the suitable component in the Proteus.
2. To simulate the design in the Proteus.
3. To test code input and output.

WEEK 10 (27 sept - 1 Oct 2010)

Design Circuit Diagram in Proteus, Select proper input/output, Code test input/output and test PCB

This is a first design in the Proteus software. the design is not complete because in the library not have a distance sensor as a input. This design use micro-controller PIC 16f84A as a main controller in the systems. Two motor will use for movement the robot or as a output. Distance sensor as a input to detect the object in front of.

Servo Motor as a output for movement are selected. This servo motor able to control the position of the motor. The specification of this motor are suitable for the design of the robot. Two servo motor will used.

    Specification of servo motor

    - C36S=C36R
    - Speed (sec/60deg): 0.16/4.8V, 0.14/6.0V
    - Torque (Kg-cm): 3.5/4.8V, 4.5/6.0V (Maximum 6.0V)
    - Size (mm): 40.8x20.18x36.5
    - pulse width  range: 0.546ms to 2.4ms (estimation)
    - Weight (g): 36
    - Designed for "closed feedback".
    - Able to control the position of the motor

 

 
 

WEEK 9 (20 - 24 Sept 2010)

1. Triangular Sensor

Triangulation sensor

Optical Triangulation Sensors are commonly used to provide door mounted safety detection on swinging automatic doors.

These types of sensors are very common and manufactured in very high volumes. When automatic swinging doors open and close, it is important that they do not come into contact with pedestrians passing through the door.

Sensors used in the automatic door industry typically fall into four categories:

1. Microwave Sensors used to detect motion of a person as they approach an automatic door,
2. Reflective Optical Sensors that are mounted on the door header and detect the presence of a person in the door path
3. Camera based sensors that are also mounted on the door header and detect presence (a competing technology to Reflective Optical Sensors); and
4. Triangulation sensors which are mounted on the door and move with the door to provide safety.

Reflective and Camera technologies do not perform well on moving swing doors, because they typically depend upon detection of changes in the background. A sensor mounted on a swing door system is constantly in motion, so the background (i.e. floor beneath the door) changes continuously. To overcome this problem, a triangulation sensor provides an innovative solution.

2. Infra Red Sensor

 Infrared Sensor

 An infrared sensor is an electronic device that emits and/or detects infrared radiation in order to sense some aspect of its surroundings. Infrared sensors can measure the heat of an object, as well as detect motion. Many of these types of sensors only measure infrared radiation, rather than emitting it, and thus are known as passive infrared (PIR) sensors. 

Honeywell infrared detectors control or generate an electric current when irradiated. These metal or plastic products are available in a variety of electro-optical characteristics, package styles and mounting configurations. Often used with a corresponding emitter.

Best Used For:
Applications requiring object presence and limit sensing, position encoding, movement detection and counting. 

3. Ultrasonic Sensor

 
 

Ultrasonic sensors (also known as tranceivers when they both send and receive) work on a principle similar to radar or sonar which evaluate attributes of a target by interpreting the echoes from radio or sound waves respectively. Ultrasonic sensors generate high frequency sound waves and evaluate the echo which is received back by the sensor. Sensors calculate the time interval between sending the signal and receiving the echo to determine the distance to an object. 

Ultrasonic Sensor Compact Ultrasonic Sensor suitable for dual use, with high-performance characteristics. Standard operating frequency and good sensitivity. Ideal for use in range measurements, robot applications, alarm sensors, etc.
Part Code: US1240
Features • Excellent Directivity and Sensitivity • Detection Range: Up to 12m • Nominal Frequency: 40kHz • Operating Temperature: -30oC to +85oC • Dimensions: 12mm Diameter, 10mm High excluding pins, Pins - 5mm High