# The Sense of Agency in Human-Machine Interaction Systems
## 4 Improving the SoA
### Improving the SoA in a Teleoperation System  
Teleoperation has always been an important branch of HMI systems [118] and has a wide range of applications in remote medical care, deep-sea exploration, anti-terrorism, riot control, etc. Teleoperation refers to the remote control of machines or systems by human operators through a user interface, allowing for the interaction with and manipulation of distant environments [119]. In teleoperation, maintaining the operator's SoA is crucial for effective control and decision-making. Sensory feedback, including haptic feedback, plays a vital role in bridging the physical distance between the operator and the controlled system, thereby enhancing the operator's sense of control and presence in the remote environment. Therefore, sensory feedback signals are critical for maintaining the SoA in such systems. Sensory feedback can be used to improve the transparency and acceptability of the teleoperation system. Haptic feedback is one of the most commonly used sensory signals in teleoperation systems. Haptic feedback in teleoperation refers to the use of the sense of touch to convey information from the remote environment to the operator. A practical example is in robotic surgery, where surgeons can feel the resistance of tissues through force feedback in the control interface, allowing them to manipulate surgical instruments more precisely and intuitively [120]. Many studies have shown that teleoperation systems with haptic feedback result in more efficient and stable human-machine collaborative operation [121; 122; 123]. Haptic feedback increases the operator's telepresence and the transparency of the system, as haptic feedback helps operators not only feel the physical properties of the remote environment but also control the remote machine more accurately. In addition, haptic feedback provides additional perceptual information to enhance perceptual consistency, improve the realism of the operation, and make it easier for users to immerse themselves in the task, thereby enhancing their SoA [124; 125; 126]. Haptic feedback integrates multiple forms of sensory information by adding a sensory channel (touch), making the user's operating experience richer and more three-dimensional and helping to improve the sense of subjectivity. Especially in skin-based interactions, haptic feedback acts directly on the user's body, making it easier for the user to perceive the connection between their behavior and their body, thereby enhancing the sense of subjectivity [127]. Therefore, we can affirm that haptic feedback improves the SoA of teleoperation systems, even if the articles on haptic feedback did not discuss the SoA. [PERSON] et al. [128] designed four different auditory feedback conditions to perform tracking tasks in the virtual environment with different degrees of automation to manipulate virtual robot fixtures. The experimental results showed that auditory feedback suppressed the decline in the SoA at the medium automation level. Among various teleoperation systems, assistance systems are important for tasks that cannot be completed independently by humans. For instance, to solve the problem of low work efficiency in remote operations on construction machinery due to the lack of perspective, [PERSON] et al. [129] developed a semiautomatic system that obtained a high work efficiency and realized a similar control feeling to manual control. [PERSON] et al. [130] studied the application of an assistance system in remote train-driving training, which showed that to overcome the difference between local driving and remote driving, an assistance system must be integrated. [PERSON] et al. [131] proposed a context-aware assistance method that can retrieve user performance and the SoA and used Air Hockey (a two-dimensional physical game) as a test platform. [PERSON] et al. [131] predicted the trajectory of ice hockey from real-time-captured video and provided striker control assistance to players according to the context.