## 4 Current Issues and Challenges of Realising the Tactile Internet
### Challenges Related to Kinematic Devices
#### 4.12.1 Kinematic Sensors  
There are different types of sensors available for capturing or tracking the movements at the operator end. We will discuss a few of the approaches that are being used to devise kinematic sensors. Simple mechanical frameworks are adopted to capture the moment and are generally equipped with some connections and electrochemical transducers such as a potentiometer to follow the motion. There are also other methods for tracking the movements of the body such as [101; 102; 103; 104; 105; 106]: (a) Magnetic-based strategy is used wherein magnetic sensors are deployed at different parts of the body and as the body moves, the sensor tracks the movement of the body and records its position; (b) In radio-frequency identification (RFID)-based strategies, the radio-frequency tags and sensors are used to gather the movements of the body; (c) Image sensors are also strategised to catch an image at stipulated period, and then it is processed to evaluate the position/motion of the body; (d) Capacitive-based techniques are also used to capture the body movement with the deployment of capacitive sensor arrays, placed in proximity to the body. Here, a parallel plate of the capacitance concept is used between the body and sensors, noting a change in capacitance as the body moves, and many more. Many recent techniques have been developed to sense and track the movement of the body at the operator end.  
Despite possessing such techniques, there are always some limitations regarding the recreation of the movements at the teleoperator end. Moreover, many are helpful in catching just motion [105; 107; 108]. This is not helpful in haptic frameworks where the operator movement is to be steadfastly followed and replicated. Even though these strategies can be used to track movements, such attempts will give coarse information focussing on the movement being detected.  
Although these strategies execute admirably in a few haptic cases, they fail when the user handles the duplication of the remote activity. There will also be a limitation for image sensors where it demands the operator focus on the sensors, which restricts the working zone of the user. This imaging strategy also experiences the blockage of the blood vessel, resulting in the loss of free movement, gripping, etc.  
Notwithstanding a couple of exceptional cases, there are a few strategies such as capacitive, magnetic and RFID-based strategies, which request the operator to connect sensors as wearable gadgets. Wearable gadgets such as tactile gloves can be developed with necessary sensors to track or capture the operator's motion using such strategies. In addition, a similar glove can likewise consolidate haptic actuators to facilitate haptic feedback. On the contrary, it can be awkward to wear glove-based gadgets in certain use cases.  
Another significant thought to be considered is the output time or scanning time. This additionally incorporates the time it takes to scan and track the operator kinematic movement. If multiple sensors are present in the TI system, each individual sensor will have its scan time constraint, and processing it could be a challenge to achieve 1 ms TI constraint. Because of the limitations of sensors that support low baud rate embedded protocols to transfer the sensor information, this forces the master section to seek sensor information, each one in turn. This seeking time can add up to the general output time of the kinematic strategy. A solution here is for the device calculation to powerfully pick the sensor of intrigue and dynamically read the information instead of scanning the sensor one at a time or in a stipulated sequence. Therefore, more research is required to solve this problem.  
As discussed above regarding processing time or scanning time, still kinematic strategies adopt refined kinematic algorithms to capture movement. These algorithms contribute to more processing time. Therefore, conceivable arrangements can be adopted by computing all the information in the cloud.