## 5 Snake Robot Design Considerations for SAR Response Phase
### Mechanical/Hardware Design  
The physical characteristics of the robot, i.e., its length, diameter, number of modules, and weight, are crucial for SAR operations. Assume that robots must move through a limited environment and that greater length and size restrict their ability to access and move within that environment. On the contrary, small size and length prevent the inclusion of the required sensors or hardware, which may restrict the robot's operating potential. As a result, the robot cannot always behave as per rescue personnel and victims' expectations. Additionally, the robot may restrict data collection due to fewer sensors. However, modern integrated circuits (IC) and nanotechnologies are working to significantly reduce the size of the components, making it possible to fit more hardware into a small area.  
The majority of physically realised snake robots in the literature [97; 98; 99; 100] utilise rigid actuation, which is dangerous for interactions with humans and offers only a limited degree of environment adaptability. These design problems lead to ethical concerns with SAR robots. As a result, stiff/rigid actuation systems are not recommended. Conversely, using soft and elastic actuation during SAR may offer benefits like compliance, safety, dexterity, etc. Additionally, it makes robot interactions intrinsically safe and therefore addresses the corresponding ethical problems. Accordingly, a few soft and elastic actuated snake robots were built in [88; 101; 102; 103] by exploiting soft robotics advantages [104]. Further, the addition of many sensors (i.e., camera, IR, Lidar, temperature, gyroscope, accelerometer, smoke, and haptic) enhances the ability to discover, locate, and evaluate the victim's health. However, it will have value conflicts with safety and data privacy. The regulatory bodies must decide which sensors can be used in SAR and what kind of data can be accessed (Figure 4).  
Additionally, a snake robot may be used as a multi-agent system by utilising its modular design. [PERSON] et al. discussed the benefits of employing a multi-agent system for SAR in [62]. With this, the large or heavy snake robot may be easily transported and deployed by humans or drones to a disaster situation to start quick rescue operations. One of the critical requirements for SAR interventions is to quickly deploy the technology at the disaster site. In the case of the Mexico earthquake [5], this was not performed immediately, which put a limit on rescuers' ability to achieve their goals. Further, modular design provides the advantage of distributed weight by using multiple components (e.g., batteries and electronics) in different sections. Also, snake robots can mount redundant microcontrollers and sensors to increase robustness as shown in Figure 4a. In case of any damage to one of the modules during the operation, we can disengage it and replace it with other modules for further operation, as an illustration, see Figure 4b.  
In any disaster, communication (i.e., internet, mobile signals) networks will be destroyed, which makes rescue teams difficult to communicate and perform autonomous operations. This problem can be addressed by using temporarily restoring the communication channels using drones [105]. These approaches enable the rescue team to quickly and effectively access the disaster situation, improving their ability to intervene, they may also help society to build trust and expectations of technology.  
Finally, it's critical to take into account how victims view snake robots. Given that most people are terrified of biological snakes, will the victim's fight be the same as biological snakes when a robot approaches to help them? How should the snake be designed so that victims feel safe when they see it? How would the gait patterns affect the victim's condition? These kinds of different ethical concerns need philosophical discussions going forward.