This project will help experimental
scientists save time and improve the performance of their experiments by eliminating human error at the time of sampling. We created an autosampler made up of a robotic arm that will allow us to make different movements within a pre-established surface, also, will allow us to make 12 different samples.
KEY WORDS: Automation, technologies, instrument, sampling.
Step 1: The Autosampler
An analytical chemist can deal with different kinds of problems.One of those problems are the three types of error. These are considered gross or accidental, random and systematic errors.
Rude errors are quickly recognized: they can be defined as errors that are so important that there is no other real alternative than to abandon the experiment and start over completely. Random errors affect the precision or reproducibility of an experiment. Systematic errors cause the mean value of a set of repeated measures to deviate from the true value.
Systematic errors arise not only from procedures and apparatus; can also proceed from human bias. Some chemicals suffer from some degree of astigmatism or color blindness, which could lead to errors in instrument readings and other observations..
The control of robot manipulators is a subject of automatic control in force and of great interest to the scientific community of robots due to the theoretical and practical challenges that involves the design of new strategies of control with high performance and accuracy in industrial applications such as stowage of boxes, assemblies, transfer, painting of objects, etc.The design of new control schemes involves substantially improving the performance of traditional control algorithms. Programmable automation is identified with manufacturing systems in which the production equipment is designed to be able to change the sequence of operation in order to adapt to the manufacture of different products.
The production sequence is controlled by a program, which is a set of instructions that can be changed to make a new product.
Automatic samplers are ubiquitous tools in laboratories, and an integral part of many analytical instruments. However, most autosamplers are expensive and, as such, are not used in all laboratories.
One option is to buy an analytical instrument without its autosampler and integrate an automatic injector from another supplier. Using scripts, it is possible to couple any autosampler with any analytical instrument, as long as both have a graphical user interface (GUI). Here we show that it is possible to integrate a cheap robotic arm kit, which has a GUI, to any analytical device that also has a GUI. The link is simple and does not require any electronic knowledge. The configuration is an economical alternative to common automatic liquid injectors.
Step 2: Design
We opted for the design because it facilitates sampling.
It began with a design in SolidWorks in which a prototype was created consisting of a robotic arm and a base, with a total surface of 35x25x10cm.
Step 3: Base
In the first image, the finished base is shown, with the holes where the test tubes will be placed and a container where the syringe will be rinsed.
The holes were then made for the servo motors. Once the orifices of the servomotors were realized, they were continued with the placement of these. In addition, the pieces forming the robotic arm of the autosampler were created and assembled. As shown in the images
Step 4: Suction
For the part that sucked the fluids were analyzed several options, after a long analysis the decision was made to create a suction system consisting of a syringe with the millimeter screw plunger, which is connected to a motor step by means of a bolt metal.
For the manufacture of this piece a millimeter screw was used, with its respective nut, a steel bolt, a 5 ml syringe, a transparent 0.5 ml diameter hose and a plastic pipette. The screw underwent a modification in the head, which was turned with the shape of the original plunger, in order that the packaging fit correctly. In addition, one is realized that will serve like guide so that the plunger does not turn, but has a linear slip.
Step 5: Program
To automate our sampler, a program was done in the arduino software, which controls each of the servomotors responsible for moving the arm, as well as controls the motor in steps, which is responsible for the suction syringe work.
Step 6: Results
A autosampler was obtained capable of continuously taking 12 different samples, with a volume range between 1 and 5 ml each sample, the volume can be modified from the source of the autosampler.
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