The information for this experiment is described as follows.

Participants

The test was conducted with 12 firefighters that were dispatched to the National Research Institute of Fire and Disaster. Their backgrounds and headquarters were scattered. All participants were informed about the handling of data and personal information obtained in the study, and consent was obtained from all participants. Table 5 shows the participants’ experience in firefighting, defense, prevention, and oil refining facilities. Defense is an activity in which the fire department directly exercises its firefighting power. Prevention is an activity based on the Fire Service Act that supports and ensures proactive efforts in private enterprises.

Table 5 Participants’ experience in firefighting, defense, prevention, and oil refining facilities

Types of information presentation

  1. (1)

    Type I: Display the checklist information in an order that takes the COCOM into account. The information is displayed in the order of the strategic control mode, tactical control mode, and the opportunistic control mode. The participants could switch between the control modes at their own discretion. When a participant switches a message, he/she cannot see the previous message. This type is the proposed method in this study.

  2. (2)

    Type II: Display the checklist information in an order without considering the COCOM.Regardless of the control mode, the evaluation items were displayed in a discrete order. The participants could switch between control modes at their own discretion. When a participant switches a message, he/she cannot see the previous message. This type improves the attention to the checklist information due to its prominence from the sense of discomfort [25].

  3. (3)

    Type III: Display all the checklist information at once. The information is displayed in the order of the strategic control mode, tactical control mode, and opportunistic control mode. This type reduces the possibility of missing the checklist information due to increased multitasking [26].

In this experiment, the participants are multitasking to view the checklist information while operating the robot. In Type I, there is a possibility of missing or forgetting checklist information because of the switching of checklist information. Type II and Type III scores may be better than Type I scores because Type II and Type III are less prone to missing or forgetting checklist information.

To eliminate the order effect, this study varied the order of the types for each participant, such as type I → type II → type III for participant A and type I → type III → type II for participant B.

Targeted firefighting activities and their objectives.

Reconnaissance activity: Gather information on the fire site.

Attenuation activity: Determine the location of the water discharge.

Configuration

  1. (1)

    Reconnaissance activity

    Disaster situation: An epicentral earthquake has caused fires to break out simultaneously in many places in the prefecture. Citizens reported that there were fires in a residential area.

    Purpose of the reconnaissance: To begin the water discharge as soon as the fire engine arrives in this area, the firefighters reconnoiter with the teleoperated robot and decide on the positions for the water discharge.

    Activity timing: For the sake of simplicity, the participants started reconnaissance after the evacuation of the citizens was completed.

    Weather conditions: Table 6 summarizes the weather conditions that were considered in this experiment. It was assumed that the weather conditions resemble a summer day in the capital region in Japan. This is similar to the seasons in which this experiment was performed.

  2. (2)

    Attenuation activity

    Disaster situation: An epicentral earthquake has caused fires to break out simultaneously in many places in the prefecture. The valve of the oil refinery was loosened by an earthquake, and hydrogen gas leaked.

    Purpose of the attenuation: To allow office staff and fire brigade members to enter the leak site and perform the work to stop the leak.

    Activity timing: To make the experiment easier, the participants started the attenuation of hydrogen gas after the citizens or office staff evacuated. Only hydrogen gas leaked, no fire had occurred, and all the facilities were operating.

    Leak area: The participants were informed that the leaking area of the hydrogen gas was inside the first floor of the central facility, which is preliminary information. The participants were also notified about the percentage lower explosive limit (% LEL) data of the leak area. The % LEL is the degree to which the explosive limit is reached, and when this percentage reaches 100%, it indicates an environment in which an explosion can occur. Hydrogen gas concentrations can be obtained from gas detection sensors that are installed at various locations in the facility.

    Weather conditions: The weather conditions in this experiment are listed in Table 7. It was assumed that the weather conditions resemble a typical summer day in the capital region in Japan, which is similar to the season when the experiment was performed.

Table 6 Weather conditions
Table 7 Weather conditions

Environment

The experiment was conducted by using computer simulations that were constructed with ROS, Gazebo, and Rviz. The reconnaissance and attenuation were conducted in the environments that are shown in Figs. 3 and 4, respectively. Figure 3 shows a dense area of four apartment buildings. Figure 4 shows the area of the oil refining facilities in a petroleum complex.

Fig. 3
figure 3

Experimental field of reconnaissance

Fig. 4
figure 4

Experimental field of attenuation

For the fire, this study used the image of the flag that is shown in Fig. 5, which is used during fire training. The yellow smoke flag used in this experiment indicates that it is not simply burning, but a growing flame. Since the firefighters use this flag in their daily training, the difference in cognition of flame is expected to be smaller than the computer graphics flame. The emergency entrance in the Building Standard Act is represented by an equilateral triangle, as in the real world, and the water source is represented by a fire hydrant in the simulator.

Fig. 5
figure 5

Equipment in the experimental field

Robot

The robot that was used in this simulation was developed based on Husky [27] and it was equipped with a pan-tilt camera (white part) to allow a visual confirmation of the surrounding environment (Fig. 6). In this experiment, a single camera system was used to eliminate the effect of multiple camera windows layout In addition, a water cannon with the following performance was set to be in the same location as the pan-tilt camera. Movement of the robot after arrival at the water discharge position was not allowed. The robot was assumed to be explosion-proof.

  • ・Water discharge amount: 4,000 L/min.

  • ・Type of water discharge.

Fig. 6
figure 6

Straight (width: approximately 2.5 m, range: approximately 75 m, height: approximately 30 m)

Wide-range (width: approximately 7 m, range: approximately 30 m, height: approximately 15 m)

The robot can be controlled by a gamepad or mouse, and the roles of each are as follows:

To prevent the participants from malfunctioning, not all the operations can be performed with the gamepad, but they are deliberately separated. The messages to be displayed were switched by the signal of the participants. Specifically, the participants were asked to switch messages when the current information became unnecessary. However, once the participants switch messages, they cannot return to the previous message.

The operation screen of the robot is illustrated in Fig. 7. The operation screen has two windows: one for the camera image and the other for the work support messages.

Fig. 7
figure 7

Operation screen of the robot

As an example, the switching of work support messages in the case of type I and the reconnaissance activity is shown in Fig. 8. In type I, these are switched in the COCOM order, and in type II, they are switched in a random order. In type III, all of this information is displayed at once. Figure 9 shows the operating stations that are used in this experiment.

Fig. 8
figure 8

Switching the work support messages for type I and the reconnaissance activity

Fig. 9
figure 9

Operator station for this experiment

Presentation message

Table 8 shows the messages that are presented during the reconnaissance activities, and Table 9 shows the messages that are presented during the attenuation activities. These messages were presented on the display, as shown in Fig. 8.

Table 8 Presentation messages during the reconnaissance activity
Table 9 Presentation messages during the attenuation activity

Procedure

  1. (1)

    Experimental explanation and simulator operation

  2. (2)

    Have the participants reconnoiter the disaster site (dense area of an apartment building) by using the robot.

  3. (3)

    Have the participants fill out the questionnaire after completing one trial.

  4. (4)

    Have the participants attenuate the hydrogen gas at another disaster site (the area of the oil refining facilities). This study did not cover the water discharge, but only the determination of the water discharge position.

  5. (5)

    Interviews were conducted with each participant based on the results of the questionnaire.

In the questionnaire, the following items were confirmed for the reconnaissance and attenuation.

  • What are the items you checked during the reconnaissance/attenuation activities?

  • What is the order in which you checked the items that are listed in the previous question?

  • Which items would you not have checked during the reconnaissance/attenuation if you had not received the work support message?

  • Which item is the most difficult to check?

  • Which of the three work support messages is easier to use?

Evaluation

This study conducted two types of evaluations for each information presentation method: a subjective evaluation and an objective evaluation. The subjective evaluation was based on the user’s ranking of easy-to-use methods and the mental workload measurement by NASA-TLX [28]. Here, the mental workload refers to the workload that was subjectively felt by the participants, which is different from the cognitive load (the amount of working memory resources that are used). The objective evaluation was based on the number of evaluation items and the Levenshtein distance. The basis sequence for calculating the Levenshtein distances is the strategic, the tactical, and the opportunistic control mode. However, since this sequence is based on the hypothesis in “Approach” chapter, the validity of the hypothesis is checked by the number of evaluation items, and then the evaluation by the Levenshtein distance is conducted.

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