This week from Monday to Friday, every afternoon, our group go to the library to cooperate for several hours. We brought all the things we were doing to the school and then formed them into a prototype. In the process, we encountered some difficulties.
- A student in our group is responsible for purchasing related equipment in the chemistry laboratory. In the past few weeks, we first linked the relevant sensors on the board in their respective homes. After we arrived at school, the first problem to be solved was how to fix various sensors on chemical experiment tools. The hardest thing to fix is the button. The four legs of the Button are very short. We used a lot of stupid and primitive methods to fix it, such as entangle the legs of the button with the wire, and then use string and tape to tie them. They all failed in the end, so we tried to find other tools in Building 78. Finally, the tutor provides us with a better button.
- Secondly, another problem we encountered is that "Solder" is really not a good way to fix and connect wires and sensors. Sensors that have been soldered will break after about 3 days of use. In the end, we still chose the stupid way, which is to fix them with tape at the junction of the wires.
- Another problem is that there are too many wires used in the entire device. Our improvement method is to use pull-up resistors instead of ordinary resistors in Arduino. This method can only remove some resistance, but for analog signals, this method is not good. At the beginning, after we used the PULLUP resistor, we removed all the resistors，and connected the sensors of digital signals and analog signals to the positive and negative electrodes, but the entire device was no longer running. Opening the monitoring window, we saw that all the printed characters are garbled. Later, we discovered that the sensors using analog signals interfered with other sensors. Therefore, we only placed resistors at the connection of the analog signal sensor. Now, the simplified circuit still has many wires, which is very ugly.
- We currently use the tilt switch to control the delete function of the test tube and beaker. Because the serial port on the board is not enough, we hope to reduce the number of sensors. In our design, we have a playback function, this function requires the use of 6 vibration sensors. We tried to use the tilt switch to control two variables, one is to let the tilt switch use "1" and "0" to control whether to delete the sound. Another variable is that within 3 seconds, the tilt switch count is above 20 so that the sound is played.
Regarding the mixing section, this section has three functions, one is to accept the sound stored in the test tube and jar, the other is to play the mixing, and the third is to delete the mixing. According to the experience of chemical experiments, people usually use pouring method to pour liquid from test tubes and jars into flasks. Therefore, I decided to use the tilt switch to detect the placement direction of the test tube and jar. When the direction changes, the tilt switch can be triggered. The way to use the flask is usually shaking, so I plan to buy a sensor to detect shaking. During the purchase of the flask, I saw the flask on the product poster and mistakenly thought that the actual kit also contained a flask, but when I opened the product, I found that there was only one beaker. Since I did n’t have enough time to buy the flask, in this demo, I replaced the flask with a beaker.
It was originally planned that in the entire device, all delete functions will be triggered by the button, but in actual production, because the four feet of the button is very short and cannot be well fixed on the beaker, I considered two other methods for the delete function. Method 1: Make a trash can, install an infrared distance detection sensor on the trash can, and delete the sound in the beaker when it detects the beaker approaching. The second method is to use a tilt switch. The tilt switch in the beaker controls two variables, one is the shaking trigger mixing function, and the other is the dump trigger deleting function.