Sensors & Measurement

Define the following term of a measurement system: (i) Accuracy, (ii) Hysteresis error, (iii) Sensitivity.

Write notes on the following sensors: (i) Tactile sensor, (ii) Pneumatic sensor, (iii) Capacitive sensor.

What will be the change in resistance of electrical resistance strain gauge with a gauge factor of 0.001?

What is transducer? How are transducers classified?

Explain how a capacitive sensor works? How does it work as a proximity sensor?

A strain gauge is bounded to a beam which is 12 cm long and has a cross sectional area of $3.8 \text{ cm}^2$. The unstrained resistance and gauge factor of the strain gauge are $220 \Omega$ and $2.2$ respectively. On the application of load the resistance of the gauge change by $0.015 \Omega$. If the modulus of elasticity of steel is $207 \text{ GN/m}^2$, calculate: (i) the change in length of the steel beam, (ii) the amount of force applied to the beam.

Define the following term of a measurement system:
Accuracy
Sensitivity
Repeatability
Resolution

Draw a typical unit-step response of a $2^{nd}$ order system and show related specifications of the response.

Describe the principle and working of piezoelectric sensor.

Write down the selection criteria of a PLC.

Draw the ladder diagram and output diagram for the following logic gates:
(i) AND (ii) OR (iii) NAND.

Measurement is an important subsystem of a mechatronics system – why? Discuss briefly.

What is the difference between a sensor and transducer?

What is Hall effect? Explain with a neat sketch the principle of Hall effect sensor.

Explain the significance of the specifications for a strain gauge pressure sensor as given below:

• Range : 70 to 1000 kPa, 2000 to 70,000 kPa
• Supply voltage : 10V d.c. or a.c. rms.
• Full range output : 40 mV
• Non-linearity and hysteresis : $\pm 0.5$ % full range output
• Temperature range : $-54^{\circ}\text{C}$ to $+120^{\circ}\text{C}$
• Thermal zero shift : $0.03$ % full range output / $^{\circ}\text{C}$

What do you understand by the term 'Mechatronics'? How do you state the approach of mechatronics?

Write down the basic elements of a closed-loop control system. Identify these elements in a system used to maintain a constant water level in a tank.

How do you differentiate a sensor from a transducer? Write down the selection criteria of a sensor. Make a list of various types of sensor.

Define the following terms for transducer:
Range and span
Sensitivity
Repeatability
Resolution
Non-linearity error.

Explain the working principle of the following transducers (any three):
Optical encoder
Pyro electric sensors
LVDT
Ultrasonic sensor.

Briefly explain the working principle of pneumatic sensor.