|
| Application | Sensor type | Description |
|
| Force actuation | Pressure sensor | The pressure sensor provides the feedback of the air pressure applied by the pneumatic actuator [226]. |
| Torque sensor | The torque output by the electrical motor is measured by the torque sensor [222]. |
| Robot body shape estimation | Potentiometer | Potentiometers consist of sliding or rotating contacts, which are installed to know the length of each segment of the continuum robot based on the change in the voltage [224]. |
| Image camera | An image camera consists of a high-resolution lens with a maximum frame rate to estimate the shape in real time using image processing and machine vision techniques. Common examples include Dalsa camera, Kinect camera, XCD X710 digital camera, AK 4, and AK7 [229, 230, 232–234]. |
| Resistor shape sensor | The resistive sensor is sensitive to twisting or elongation and changes its resistance proportional to the deflection [237, 240]. |
| Fiber Bragg gratings | FBG are similar to optical sensors. These sensors are mostly used to obtain the curvature of the robot body in the static and dynamic mode by obtaining the strain information at different locations along the structure [223, 227]. |
| Dielectric elastomer | This sensor is embedded into the actuators with distributed actuation points that could cover soft bodies. It is highly flexible and can be adaptable to soft structures to obtain information regarding surface deflections. The examples used in robotics include DEAs, VHB 4910 [236, 238]. |
| Magnetoresistive sensor | The magnetoresistive sensor is mostly used to detect any kind of geometrical deflection or thermal sensitivity and provides an output based on the desired parameters, e.g., contraction of a bundled actuator [225]. |
| End-effector position estimation | 3D electromagnetic sensor | These sensors are generic sensors that are electromagnetic wave emitters and are installed onto the shape of the robot and emit the signals in regular intervals captured by receivers [192]. |
| Infrared sensor | An infrared sensor is less accurate when compared to other electromagnetic sensors because of temperature sensitivity. It emits radiation to estimate the relative coordinate position, e.g., MicroScribe MX [180]. |
| Optical sensor | The optical sensor is the most accurate sensor for estimating the coordinate positions of any robotic component. It is used for modulating the intensity of light from the specific position to estimate the relative distance, which can also be used to estimate the shape of the robot, e.g., Micron Tracker SX60 [235]. |
| Laser sensor | The laser sensor is a type of optical sensor that is capable of projecting electromagnetic radiation to a specific point on the end effector to obtain the relative position coordinates, e.g., FARO Edge laser [34]. |
|
