Pressure Sensor for Robotics Applications

Pressure sensors can be habit to metric force, and in some cases, to shape the periphery of an attach strength. A capacitive pressure sensor employs two temper piece separated by a couch of nonconductive froth. This forms a capacitive transducer. The transducer is joined in sequence or concurrent with an inductor. The inference inductance-electrical capacity (LC) combination finishes the frequency of an oscillator. If there is show lower or oppress against the transducer, the spacing course decreases causing the origin of capacitance to increase.

This decreases the oscillator frequency. When the pressure is emitted from the plates, the foam strikes back, the plates revert to their genuine spacing, and the oscillator respond to its original frequency. Any metallic object can fool a pressure sensor having capacitive characteristics. Since the capacitance is inductive in nature, in case of a great electrical conductor, capacitance can alter itself without even making any physical contact. This is one of the disadvantages of capacitive pressure sensor. This proxy sense can be sensed as a change in pressure by capacitive pressure sensors.

This drawback of capacitive type of pressure sensor can be solved by introducing elastomer type of pressure sensor. Here is a interesting explanation about the concept. The proximity problem can be solved with an easy by elastomer devices. For those who don’t know what elastomer devices are made of, try and think of a foam pad with variable resistance. This resistance is variable because it varies in accordance with the pressure applied to the foam pad. This structure consist of a bunch of similar electrodes connected at the top of the pad and the one more similar set of electrodes is connected at the bottom of the pad. It works on the principle of nodal analysis of current. As we know the node principle, the amount of current going in a node is same as the amount of current going out of that node and that makes the total current zero. Similar to this, the upper set of electrodes takes negative voltage and another set of electrodes receives a positive voltage. When we apply the pressure at any point of the pad, it compresses and the resistance between the electrode pairs decreases. This comes with an increment in current in a particular region in the foam pad.

Elastomer devices are better than capacitive ones in many senses. With capacitive types of sensors, it is a bit hard to convert analog signals to digital ones but with elastomer sensors, conversion becomes very easy.


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