Power supply for Arduino First we are going to mount the load cell. Illustration of Load cell: This type of load cell is rigid and used commonly in industries. It has two stages of amplifier with reference amplifier. The other mode will be covered in the next instalment of the force sensor project where the Processing Application will be introduced. Load cell comes in various ranges like 5kg, 10kg, 100kg and more, here we have used Load cell, which can weight upto 40kg.
Each and every components are described below further. To it up as a scale, you attach the bottom left or right screw holes to a table or stable object, and then attach a piece of platic or any other material to serve as the scale to put objects on, to the top opposite screw holes. And if user wants to calibrate it manually then press the push button. . The most difficult part will be connecting the load cell if a pin connector crimping kit is not available. Beware there will always be noise - you probably want some filterung in what you display, again see typical examples.
Now, we have converted a deformation or weight or force to voltage signal. Working with a Load Cell and an Arduino We built a system that uses eight to push down on a piece of glass to seal it to a sidewall. Any one side must be stationary for best accuracy; it may be mounded to a wood with reasonable weight. Once everything is hooked up, we just needed to write a program that would read analog pin 0 on the arduino, since that's where we hooked up the output of the amplifier. In modern times, we measure weights in kilograms, milligrams even micrograms for laboratory purpose. And try to implement a low pass digital filter too, it should compensate the fluctuations and would give you smoother signal. Designing the Arduino based Weight Scale: Most of the measuring instruments contain switches on their bodies that are for different purposes.
You might have to infer a little from the colors that you have, but in general you will usually see these colors. These are quite expensive if you are heading to buy one. The Arduino, which provide 10 bits of resolution i. Example of a single strain gauge, or load sensor. Images are provided as a quick reference to the calibration procedure. Scale is designed with -+0.
The sketch can be found here on my GitHub: Calibration and seed-setting sketches can also be found here: The library can be found here: And if you use an Arduino Micro or Sparkfun Pro Micro what do you have to guard against if you don't want a 'bricked' Arduino? Load cells only make a very small change in voltage, so you have to use an to increase the voltage to something we can use. Mass is the amount of physical matter present in an object. One load cell to each load cell amplifier and then to the Arduino. The chart provides an overview of typical applications, ranging from the lowest to the highest accuracy class. It provides complete bridge excitation and precision differential input amplification on a single integrated circuit. The breakout board is compatible with any wheat-stone bridge based load cell which should allow a user to measure everything from a few grams to tens of tons.
Now do the connections as shown in the circuit diagram and you are ready to go. The breadboard can also be found on Ebay and the project uses the 400 pin version. A push button is provided to bring the weight reading to zero, this function will be explained in detail at the end. Load Cell Classification Load cells with different accuracy classes are required depending on the application. Otherwise you will loose 400 grammes off the target weight range. Remove all fixture arrangement and just put known weight directly on load cell.
Changing modes changes what data is output to the serial interface and what speed the serial interface operates at. Understanding a Wheatstone bridge: A wheat stone bridge is a circuit which can be used for determining unknown resistance. To learn more, see our. Upload the above code with your full hardware setup and your weight scale machine is ready. But, my best resolution is unstable +- 2g. The below classification is from lowest accuracy to highest accuracy range.
Circuit Explanation: Connections for this project are easy and schematic is given below. It is basically a device that measures strain and then converts force into electric energy which serves as measurement for scientists and workers. A Load cell is an aluminium profile with strain gauge attached to 4 sides in Wheatstone bridge configuration. Ignore the scale load reading at this point as it is yet to be calibrated. This is enough for this project. The large gains are needed to accommodate the small output signal from the sensor.
The mounting plate and the moving plate should both be as rigid as possible 3. It should work now, if not we can assume some issue with the load cell or load cell amplifier. I am not sure if there is a way to connect multiple load cells to the same arduino. Standoffs or washers both work well. The load cell that we will use in this is a strain gauge 10kg bar type load cell that is shown below. Yes, a single Arduino can in theory take as many scales as the number of Digital inputs you have can provide.
Here the need of power supply for load cell and instrumentation amplifier solved by Arduino power pins. Make sure to read the datasheet for the load cell you are using and get the correct screws to fit into it. Now to calculate the calibration factor we will divide this raw value by the known weight in such units for which we are designing our weight scale. We have comprehensively understood the theoritical part of the a weighing scale design from the above discussion, now let's see how a loas cell may e used for making a pratical weighing scale machine using Arduino Designing a Digital Weighing Scale Machine using Arduino In the following discussions we will learn how to construct a digital weight scale machine using Arduino which can measure weights from few grams to 40 Kg depending on the specs of your load cell with reasonable accuracy. The process is shown in the figure below: The conditioned signal is then connected to an analog input port of the Arduino microprocessor.