Here we are talking about sensors used in the Robotics. As we know that robotics uses the sensors to its maximum limits, various types of sensors are used for various purposes in various application in various locations.
Classification of Sensors Used In Robotics Based On Physical Input Quantity:
- Tactile sensor.
- Proximity Sensors.
- Range sensors.
- Navigation sensors.
- Vision sensors.
- Miscellaneous sensors.
1. Tactile Sensors:
Tactile sensors are devices which indicate contact between themselves and some other solid object-in this case, an obstacle. This kind of sensors can be subdivided into two more sutypes:
- Touch Sensors:
They are used to indicate that contact has been made between two objects without regard to the magnitude of the contraction force. A binary output signal indicates whether or not a contact has been made with the object.
Ex:- limit switches, micro switches etc.
- Force Sensors:
They are also called as stress sensors. They not only indicate that the contact has been made but also the magnitude of the contact force between the two objects.
The capacity to measure forces permits the robot to perform a number of tasks. These include the capability to grasp parts of different sizes in material handling, machine loading and assembly work, applying the appropriate level of force for the given part. In assembly applications, force sensing could be used to determine if screws have become cross-headed or if parts are jammed.
2. Proximity Sensors:
Proximity sensors are devices that indicate when an object is close to other. How close the object must be in order to activate the sensor depends upon the particular device. The distances can be anywhere from few millimeters to several feet.
Proximity sensors can be used to detect the presence or absence of a work part or object. Another important application is sensing human beings in the robot work cell. Range sensors will determine the location of an object (work part) in relation to the robot.
Ex:- optical proximity sensors, acoustical sensors, magnetic field proximity sensors.
3. Range Sensors:
This is type of sensors which can be considered very near to proximity sensors. Range sensors measure the distance between the object and the sensor. These sensors are located on the wrist or end-effecter as these are the moving parts of the robot.
4. Navigation Sensors:
As name navigation indicates, this is kind of sensors which can be used for estimate positioning of objects. This kind of sensors can be classified in two main subclasses.
- Relative Positioning Measurement:
They measure the signal within the robot itself. They can be again subdivided into:
- Proprioaptive sensor.
- Inertial navigation systems – Gyroscopes and Accelerometers.
- Odeometry.
- Absolute Positioning Measurement:
As name absolute, this sensors take measurements from some kind of fixed or universally fixed datum. Types Under This kind of sensors is:
- Magnetic Compasses.
- Global Positioning Systems (GPS).
- Active Beacons – triangulation.
- Landmark Navigation.
- Model Matching – Map matching.
5. Vision Sensors:
Machine vision is concerned with sensing of machine vision and its interpretation by a computer. The typical vision system consists of the C.C.D. camera and digitizing hardware, a digital computer and software necessary to interface them. This interface hardware and software is after referred to as a preprocesser. The operation of the vision system consists of 3 functions :
a) Sensing and digitizing data.
b) Image processing and analysis
c) Application
For object recognition, along with processing, robot programming is also necessary.
6. Miscellaneous Sensors:
This category covers the remaining types of sensors and transducers that might be used for interlocks and other purpose.
This category includes devices with the capability to sense variables such as temperature, pressure, fluid flow, velocity and electrical properties. Hence this category includes sensors and transducers like tachometers. LVDT, Pr gauges etc.
