Sunday, October 5, 2008

After long break

After fail finishing the robot for the competition, I stopped updating my blog for a while. This is because I feel a bit disappointed for not be able to finish the robot in time. Today I am going to update the result of the entire work we hove done so far.
There were some changes in our robot. The changes were stated bellow:
1. L293D for motor driver was changed into L293NE.
2. Pins that control enable/disable of motor driver were changed into pin 16 and 17 of the
PIC to support PWM (used to control the speed of the motor).
3. Additional of 1 rechargeable AAA battery and removal of 9V battery.
4. Additional of 2 Module IR sensors to detect no wall path.
5. Some changes in the circuit and circuit diagram due to all of the changes stated above.
The reason why we change the motor driver was because we found that the L293D can cause some short circuit that lighted up the other indicator LED that should not on. L293NE driver can work exactly the same as L293D without causing any of the stated problems; therefore we decide to change the motor driver. We also find out that the PWM could only be used in pin 16 and 17; therefore we change the connection of enable form the motor driver into these two pins. We also find out that 9V battery cannot be use for a long time moreover; currents of 5 AAA batteries could not drive the motor. Therefore we decide to remove the 9 V batteries can add the AAA batteries. The previous design of the robot was also used for the competition purpose; therefore we were not bothered about the no-wall case condition. The addition of 2 module IR sensors should be enough to solve the simple no-wall tract. With all of the changes, the circuit and circuit diagram of robot were also changed.
The new circuit and circuit diagram was shown bellow:

With all of the changes made, the hardware and body of the robot are complete. The last thing to do is the programming. Programming of the robot is not an easy task since we cannot know whether the program is correct or not. The only way to know is to program it one by one and test it to the robot. Finding the correct threshold is also not an easy task. With all the hard work, we finally manage to fine the best threshold voltage.
For the programming, we are trying our best to simplify the code. The left wall following algorithm is used as our first code. This algorithm set the priority to left. Whenever left is opened, the robot will turn to left. The flow chart of the main program is given bellow:

With this flow chat, our robot can solve a simple maze. Some optimization was still needed to get the best result. Until now we are still optimizing the code especially the function code.

Tuesday, August 26, 2008

Today is the day to finish my PCB. We have finalized our schematic design therefore I can finish the whole PCB.
The PCB will be a double decker PCB with the top part consist of PIC and the circuit. The bottom part will consist of 2 voltage regulator circuit, 2 switches, motor driver and a pair of motors circuit. We are using 2 battery types that consist of a 9V square DC battery and 5 rechargeable batteries of 1.2V. The 9 Volts battery will be used to drive the electronic circuit and the other for the motors.

For the chases, we are using a plate of aluminum with a thickness of 2 mm. We are using 3 SHARP IR sensors. These sensors will be placed at front, right and left. At the front of the chases will be placed 2 batteries holder with 5 batteries attached to it. Two motors will be attached at the bottom of the chases. A 9 Volts battery will be placed at the back of the bottom chases.

With all of that, the physical body of the robot is finished and ready to be built. The other problem that is needed to be done is for the programming. Right now we are still learning how to use the compiler and we hope that we will be able to finish the project on time.

Friday, August 22, 2008

First PCB design

This week we were getting part of the component. We also have finalized our base body of the robot; therefore it was the time to build the PCB. I am the person in charge of building it. At first when I am building the PCB, I am thinking of using only one decker because the entire component can fit. But after some consideration about the compactness of the PCB, we are changing our mind.
At this time we are building the microprocessor component separate from other circuit. It will become a double decker PCB with top part of PIC since we may need to plug in and out frequently. The other part of the circuit will be built on the bottom PCB. This PCB couldn’t be finalized yet since we are still not sure about the other component we will get. We are planning to use the SHARP IR sensor that will come with its own circuit.It is better to design the PCB after all of the components have been finalized therefore the changes of the PCB structure does not need to be done so frequently.

Sunday, August 17, 2008

Body Design

This is the leatest robot body design. This body use 1mm thin aluminum that can be fitted with 2 DC motors and multiple layer of PCB above.
Designed by Handy with some idea from Edy SP

Circuit Diagram

This is the leatest circuit diagram that use PIC18F452 and 2 DC motors

Second Blog

This is the 2nd block I’ve made. Until now, there wasn’t much we can do since the components haven’t arrived. For the past two weeks what all of us have done was collecting information from internet, datasheet and books.

After the gathering of information, Handy said that he will do the body design part using solid edge and he left the rest work for two of us to do. I chose to do the PCB design using the Trax Maker and Budi was in charge in schematic circuit design. So I’ve to wait for Budi to finish his design first. But then I realized that I couldn’t do the design since I didn’t know exactly the size of each component and the component that we will get. Because of that I was ending up with doing nothing. What could do is only to help them with their work. I rechecked the work they have done and gave them a feedback. I also redesign the Schematic diagram that has been done by Budi to make my life easier later when I’ve to really design the circuit.

This Wednesday was the due of the lab report, so we were more concentrated in the report for. We again divided our job to finish the report. We did the report based on the job we have assigned early. I was doing the circuit modification part, Gantt chart, network diagram, part of responsibilities matrix, part of work breakdown structures and part of activities. As most of us were quite busy with the report, we hardly done some research about the robot. On the Wednesday after the report submission, we started to discuss about the robot again.

On the day of discussion, we’ve made big changes of our robot design. We changed our plan from using servo to DC motor due to the speed limitation of the servo. The microcontroller was also changed from PIC16F87 to PIC18F452. These changes made us redesign almost all part of the robot; from the body of the robot to the circuit diagram. Though a lot of changes need to be made, I feel a bit lucky that I haven’t started to do the PCB design first.

This Friday Joshua took us to buy the DC motor. But since the car couldn’t fit a lot of people, only one of us that have gone to bought the motor. We bought the DC motor with double gear box. The wheel can move independently one another. The next day, we built the gears and wheels. At that time, we encounter a very big problem. The gear we’ve bought was incorrect and couldn’t be used. We called the shop and the shopkeeper asked us to go back to the shop to get the missing components. Finally 3 of us: I, Handy and Hendry (other groups that bought the same motor with same faulty gears) went to the shop again to get the components. After went home, we built it again and test the motor, luckily this time the motors with the gears works. The next day Handy redesigned the body of the robot. We discuss about the changes of robot and finally came out with new design. Until now what we could do was this far since we don’t have any robot’s components yet. We hope to get all of the components fast since the due date of the competition is getting nearer.

Friday, July 25, 2008

First meeting

Today is the first day to be a called a formal meeting. The meeting started at 10 am and finished at Almost all of the 4 group members were there. My team: Handy, I and Budi come a bit late because we didn’t know the venue. But luckily they haven’t started the meeting.
At the meeting, what we discussed was almost all about the hardware aspect of the robot: about the board, microcontroller, motors, sensors, etc.

A lot of ideas came in during the meeting. Pro and contra of each group happened. One of them is about the board to be used. Some of us prefer to use PCB while our group prefers strip board.
A lot of questions could not be answered either as almost all of us still haven’t had any idea due to the fist meeting.

Actually we had been given a task by our team leader Handy before the meeting. He was in charge in the physical of the robot, I was in charge of the algorithm and programming and Budi was in charge in the sensors operation. At first I thought that this job was more then enough for the starting point of view; but after the meeting I realized that actually we still have a lot of works to do…