Advantages of Tactile Sensor | Disadvantages of Tactile Sensor
This page covers advantages and disadvantages of Tactile Sensor types. It mentions benefits or advantages of Tactile Sensor and drawbacks or disadvantages of Tactile Sensor.
What is Tactile sensor ?
The sensing device which measures various parameters such as thermal conductivity, pressure distribution, touch and other stimuli is referred as tactile sensor. Tactile sensing is done using array of discrete sensing elements. Tactile sensors are widely used in touch screens of mobile phones, ATM machines, tablets, interactive digital Kiosks etc. They are also used in robotics, computer hardware, computing devices and security systems.
Tactile Sensor types
The sensing elements used in tactile sensor are of many types as follows.
• Resistive type tactile sensor include strain gauge and piezo-resistive sensing elements.
Strain gauge is made of thin film with metal pattern which changes resistance when strained.
• Pressure on piezo-resistive element causes material to compress and hance changes it's resistance.
• In capacitive type tactile sensor mechanical deformation results in variation of capacitance of parallel conducting plates.
• Piezoelectric tactile sensor measures voltage generated due to polarization under stress.
• Magnetic tactile sensor uses hall effect to measure change in flux density.
• Optical tactile sensor uses array of infrared LEDs and photo detectors.
Intensity of light is proportial to magntiude of the pressure.
• Ultrasonic tactile sensor : It uses piezo-electric component which generates motion when voltage is being applied across crystal device.
It uses array of PZT transmitter and receiver sensing devices. PZT devices generate the ultrasonic sound waves and convert voltage to motion.
• Tunnel effect tactile sensor : It is used to determine topography of surface.
• Conductive rubber type tactile sensor : In this type, pressure conductive rubber is used along with stitched electrical wires
for tactile sensing. It is thin and flexible. It can cover three dimensional objects.
Tactile sensors are basically categorized into two types viz. kinesthetic sensing and cutaneous sensing. The kinesthetic sensing primarily detects internal forces where as cutaneous sensing detects external forces. Examples of kinesthetic sensing is human perception of muscle motion and cutaneous sensing is similar to skin sensing. The criteria to measure performance of tactile sensors are sensitivity, linearity, dynamic range etc.
Advantages of Tactile Sensor
Following are the generic benefits or advantages of Tactile Sensor as well as specific to various types.
➨They are very simple in construction and provide easy to use sensing solutions.
➨They do not require any cables and external components.
➨They are available at lower costs which makes their use widespread.
➨Almost all the sensor types are sensitive.
➨Resistive type : Sensitive, low cost
➨Piezoresistive : Good sensitivity, low noise, simple electronics
➨Tunnel effect : Sensitive, physically flexible
➨Optical : Immunity to EM interference, Fast response, Sensitive, physically flexible,
No interconnections etc.
➨Capacitive : Availability of commercial A/D chips, sensitive etc.
➨Ultrasonic : Fast dynamic response, Good force resolution etc.
➨Magnetic : No mechanical hysteresis, good dynamic range, higher sensitivity,
physical robustness etc.
➨Piezoelectric : Higher bandwidth, dynamic response
➨Conductive rubber : Physically flexible
Disadvantages of Tactile Sensor
Following are the drawbacks or disadvantages of Tactile Sensor types :
➨Resistive : High power consumption, Lack of contact force measurement, generally detect single contact point etc.
➨Piezoresistive : Temperature sensitive, Signal drift, Hysteresis, Stiff and frail,
Non linear response
➨Capacitive : Cross-talk, complex electronics, hysteresis
➨Optical : Loss of light due to micro bending, bulky, chirping, complex computations, power consumption
➨Piezoelectric : Temperature sensitive, Not so robust electrical connection
➨Magnetic : Suffer from magnetic interference, somewhat bulky, complex computations, power consumption
➨Ultrasonic : Limited utility at low frequency, complex electronics, temperature sensitive
➨Tunnel effect : Non linear response
➨Conductive Rubber : Mechanical hysteresis, non linear response