When I was told that we needed to make a square by using the VEX, I were excited. It was because it was the first time for me to make a robot that can be remote contorlled by me. However, I was also puzzed when using the gears of VEX, because some of them were quite new to me. The Square Robot is the first task given to us in ELEC300R. We used only a few hour to familiar with the tools and gears of the VEX and started making on the first robot. After that we have fun on our first product. Bottle Bot is the second task for us to do in ELEC300R, it was quite challenge to me, because we still didn't familiar with the tools and gears given in VEX. The most challenging part of this task is opening the bottle. Since the motors give by vex are not very strong, they cannot provide sufficient power to open the bottle even we have used the Gong-Principle. The bottle bot is quite challange to us at the beginning. We have tried many different method to open the bottle. It took us a long time to decide which method should be used. In this task, we can know more about the tools and gears of the VEX. Besides, we learnt that how we can emphasis the power of the motor by using the gears. In this mini project, we have learnt to use the line track sensor. However, we didn't used it in following the lines ,instead we use it to sensor the "mines". It was quite interesting to me. I was very excited when the sensor first sense the "mine" and pick it up successfully. However, in this project we also found that the sensor is not sensitive enough, It some time may pass through the object without picking it up. Mini Project 2 The objective if this mini project is to make a robot that can climb up a column. In our design, one of the function of the robot is to repair the street lamp when the light bulb is blown out. The idea of this mini project came form Robocon. At that time we thought that we may climb uo the column and get the cheese, we wanted to try if it is possible the make a robot to climb up a column. But later the Robocon had banned this idea, so we decided to change the objective of this mini project, to make a robot which can help people to do some tasks by climbing up a column. The design process can be divided into two parts. The machine design and the program design. For the machine design, it can also be divided into two parts, the first part is the climbing part and the second part is the base. The climbing part is used to climb up the column. We had many generations for the climbing part. At the beginning, we designed a robot which can form a triangle around the column and there was three wheels to climb up the column. However, it is not stable and it can only climb on a fixed size column, so we decided to change our design to the second generation. In the second generation. More wheels are used in order to stabilized the robot when climbing. Besides we have made the holding part more flexible in order to climb different column. However, this generation was also failed. It was because the robot was too heavy and it was too flexible which made it difficult to hold the column tightly. Then we designed the third generation. In this generation, we have used the gears to increase the force of the robot when it climb up and hold the column. The robot of this generation can finally climb up a little bit. Hoever, there were still problem, it is the robot can damage the gears easily, it is because we had used the gears to emphasis the forece of the motors. Then we quickly move to the final project because the period for us to make the final project has started. This mini project is very difficult, we have developed many generation before the robot can climb up, and it can only climb up a little bit. The power of the motor is a problem in this mini project. Besides, even we have emphasis the force of the motor by using gears, the result is not efficient. It is because the gears broke easily. Besides, when we programming the base, we found that the line track sensor cannot always detect the white line, then it will not turn at the junction to move to the column. The general idea of the strategy is to move quickly from the ball collection area to the shooting area. In order to minimize the time to rotate the robot the shooting part of the robot was always facing the shooting area. The Sensors planned to use The sensors that we planned to use was optical encoder, the line track sensors. The optical encoder was added separately from the motor in order to get a more accurate result. It is because the wheels connected to the motor may slide, then the data will not be accurate. Here are some data got by measuring the tools,
The sequence of the programme
Besides these, there are some functions designed to be implanted with this program. 1. The walk straight programme --- When the encoder found that the right wheels walk faster than the left wheels, it will correct it by slow down the speed of the left wheels. 2. The crashing notification function --- The robot can't know that it is crashed or not easily, so we added a function, when the encode found the reading doesn't increase even the motor is moving, it will consider it is under a crash. It is move a little bit backward and try to move foward again. If it continue to sucked there, it will move back to the ball collection area and use another path to move towards the shooting area. 3. The self-locating function --- Sometime even (we thought) even the second function is implanted the robot still can't recognise the crash. Then this function will be used. When the robot is moving towards the shooting area, it should sense the white line around 80 cm away from the ball collection area. However, if is still can't find the white line after walking 90cm. It should be lost. Then it will continue to move forward untill it find a white line. Then it will follw the white line and move backward untill it found a junction. After that it will move forward and found the other junction, it will found the distance between the two junctions in order to determine if it is in the shooting area. 4. The function to find the practical error of the encoder --- We have written a program to check the actually distance travelled by the robot compare to the thorical value calculated above. ( However, the encoder couldn't rotate smoothly, we could n't carry out this testing. Here is the data sheets we planned to use. Since all the sensor couldn't work proporly on that day, we can only insert a program which disn't use any sensor. 1. The testing of the equipments ---We should test the equipments before we decide to use any of them. We need or test the accuracy of the sensors. 2. Second Plan --- We need to think of more then one plan. We should not rely only on one plan. In this project, after we have thought of a “better” plan, we gave up all the other plans. However, we hadn't thought if the plan doesn't work we still a back up program for the robot. 3. Time Management --- We should start to make the final robot earlier. We still worked hard on the second mini project for a long time after the beginning of the final project. Besides, we have spent too much time to design the machine part. These made us don't have enough time to test the program of the robot. My impression towards the course, At the time I apply this course I was very excited, it is because it was the first for me to attend a course about robotic, and I knew it would be the first time for me to make an automatic robot. After I have attended the course for a period of time, I find that making a robot is much more difficult than I have thought of. However, I was very happy that we can overcome all the difficulties that we have faced. In fact my partner was very helpful. I think we have co-operated very in this course. Although we only have two people in this group, we can also solve the problem together. Besides, Winnie was also very helpful in the course. She taught us how to make a good presentation, which is very helpful to us. Besides she has also show us what kinds of robot we can make. Moreover, Professor Li helped a lot when we gave the presentation. He also gave comment to us, which can help us to improve our presentation.
ELEC 300R Group 2 Homepage
For the base, it is easier to made when compare to the climbing part. The function of the base is to send the climbing part to the column and let it goes up. Therefore basic idea of the base is the square robot. Besides, we have added three line track sensor to let is follow the line to perform the task.
For the programming part, the basic idea is shown in the flash on the right hand side. Normally the base always follows the white line. However, if is found that the bulb of a lamp went out, it will send the climbing part to repair it. Therefore there is also a touch sensor on the base, when it found the climbing part has climb up the column, it will wait until the climbing part climb down.