Embodiment 1: (Some dashed boxes in the drawings can be marked and described as an element, and explain that these elements or units can be solved in many ways in the prior art, otherwise it may be considered as insufficient disclosure. )
 With reference to Figures 1 to 5, this embodiment includes a turtle-shaped streamlined shell, a sensor test unit installed on the front head and shoulders of the turtle-shaped streamlined shell, a control drive unit on the front chest, a power reserve unit on the lower abdomen, and a communication at the back of the tail. The system unit and the forelimb movement unit and the hind limb movement unit. The sensing test unit is composed of a sonar detector, an underwater camera, and multiple light sources. The control drive unit is composed of two controllers, an execution level and a coordination level. The power reserve unit includes a motor drive. The power supply module and the controller power supply module, and the communication system unit consists of a communication system module and an external antenna. The streamlined shell 21 is a robot streamlined shell designed to imitate the shape of a turtle shell, which not only considers the reduction of the water resistance of the robot, but also provides a carrier for the installation of internal parts of the robot.
 Combining the frame 11 in Fig. 3 and the frame part of the shoulders of the robot, the sensing test unit of the head and shoulders is composed of a sonar detector, an underwater camera, multiple light sources and related circuits. It is installed on the head and shoulders of the robot and has a wide range of action. It can obtain external information for the robot and perform tasks such as obstacle avoidance and underwater shooting.
Combined with the part of frame 13 in Fig. 3, the control drive unit of the chest is composed of two-part controllers, an execution level and a coordination level. The executive-level controller includes a motor driver and a motor controller. The motor controller adopts mature AVR technology. The main composition diagram is shown in Figure 6-Figure 9, which is used to complete the drive and control of the body motion unit (single limb), and the coordination level control The device uses mature DSP technology, and its main composition diagrams are shown in Figure 10-12, which are used to coordinate the movement of each limb according to the various swimming postures of the turtle biological prototype to realize the corresponding body movement. The motor of the turtle robot needs to run, it must have a dedicated motor driver and a motor controller that completes the single-limb motion control. As an autonomous underwater robot, the sea turtle robot must also have a coordination-level controller, which integrates the acquired external information and converts it into instructions, controls the operation of each motor, and realizes autonomous navigation. The schematic diagram of the control system of the present invention is shown in Fig. 13, and the control system adopts stack installation.
 Combined with the frame 20 in Figure 3, the power reserve unit in the abdomen uses a commonly used lithium battery, which provides power support for other units, and is the energy warehouse for the entire robot. It is divided into two parts, one part supplies power to the motor drive , Part of the power supply for the controller, separate power supply to ensure the stability and safety of the power supply system. Considering the heavy weight of the power module, it is placed on the abdomen of the robot to adjust the center of gravity of the entire robot to simulate the physical characteristics of real sea turtles.
 Combining the block diagram 19 and the external antenna 18 in FIG. 3, the communication system unit at the tail part is composed of a communication system module and an external antenna 18. Whether it is the sea turtle robot that transmits the collected data back to the host computer or the host computer issues commands to the robot, a communication system is required to enable the robot and the host computer to exchange information in real time. Therefore, we make full use of the small space at the tail of the robot to install the communication system module And an external antenna 18 is installed at the position of the turtle’s tail to keep the robot communicating smoothly at a certain depth of water.
 With reference to Figures 3 and 4, the forelimb movement unit is two sets of the same forelimb movement mechanism installed symmetrically on the left and right sides of the front of the robot. The left set of the forelimb movement mechanism is now taken for connection description. It consists of forelimb plate 1, connecting piece 25, bevel gear pair 2, small bearing 3, small shaft 4, motor shaft sleeve 5, small bearing 26, seal 6, seal 7, bearing 8, motor sleeve 9, spur gear 10. It is composed of spur gear 24, spur gear shaft 23, servo motor 12, and servo motor 22. The servo motor 12 is fixed and enclosed in the motor sleeve 9, and its output shaft is sleeved in the motor shaft sleeve 5, and the front end of the motor shaft sleeve 5 protrudes from the motor sleeve 9 after being positioned by the small bearing 26. The seal 7 adopts a skeleton oil seal dynamic seal method, is sleeved on the protruding part of the motor shaft sleeve 5, and is inlaid on the motor sleeve 9. One bevel gear in the bevel gear pair 2 is mounted on the foremost end of the motor shaft sleeve 5, and the other is mounted on the small shaft 4. The small shaft 4 is movably connected with the motor sleeve 9 through two small bearings 3. The forelimb board 1 is also fixed on the small shaft 4 through the two connecting pieces 25, so that the rotational motion output by the motor 12 is finally transmitted to the forelimb board 1. The servo motor 22 is fixed inside the robot, and its output shaft is sleeved in the spur gear shaft 23. The spur gear 24 is mounted on the spur gear shaft 23, the spur gear 10 is mounted on the motor sleeve 9, the two gears are correctly meshed, and two bearings 8 are mounted on the motor sleeve 9, so the rotation movement of the motor 22 passes through this The pair of spur gears will be transmitted to the motor sleeve 9 and finally drive the forelimb plate 1 to rotate together. The seal 6 also adopts a skeleton oil seal dynamic seal method, is sleeved on the motor sleeve 9 and inlaid on the housing 21 to prevent water flow from entering the inside of the robot.
 With reference to Figures 3 and 5, the hindlimb movement unit is two sets of the same hindlimb movement mechanism symmetrically installed on the left and right sides of the rear of the robot. The right set of them is now taken for connection description. It consists of a hind limb plate 15, a connector 33, a seal 34, a motor barrel 29, a motor barrel front cover 35, a small bearing 36, a motor shaft sleeve 37, a solid shaft 30, a hollow shaft 38, a bearing 31, a bearing 39, and a seal 32 , Seal 40, synchronous toothed wheel 16, synchronous toothed wheel 14, toothed belt 28, large motor shaft sleeve 27, servo motor 17 and servo motor 41 and so on. The servo motor 41 is fixed and enclosed in the motor barrel 29, and its output shaft is sleeved in the motor shaft sleeve 37, and the front end of the motor shaft sleeve 37 is positioned by the small bearing 36 and then extends out of the motor barrel front cover 35. The front cover 35 of the motor barrel and the motor barrel 29 are sealed and fixed. The seal 34 adopts a skeleton oil seal dynamic seal mode, is sleeved on the protruding part of the motor shaft sleeve 37, and is inlaid on the front cover 35 of the motor barrel. The connecting piece 33 is installed at the foremost end of the motor sleeve 37 and is fixedly connected to the hind limb board 15 so that the rotational movement of the motor 41 is transmitted to the hind limb board 15. The upper and lower ends of the motor barrel 29 are coaxially equipped with a real rotating shaft 30 and a hollow rotating shaft 38, and they are positioned on the housing 21 by a bearing 31 and a bearing 39, respectively. The seal 32 and the seal 40 also adopt a skeleton oil seal dynamic seal method, embedded in the housing 21, and then respectively sleeved on the real rotating shaft 30 and the hollow rotating shaft 38 to prevent water flow from entering the inside of the robot. The hollow shaft 38 adopts the form of a hollow shaft, not only to allow the line of the motor 41 to pass, but also to discharge the water that may have penetrated into the motor barrel 29 in time to protect the motor. The upper end of the real rotating shaft 30 is equipped with a synchronous toothed wheel 16, and the toothed belt 28 and the synchronous toothed wheel 14 form a complete synchronous toothed belt transmission mechanism. The synchronous gear wheel 14 is installed on the large motor shaft sleeve 27, and the large motor shaft sleeve 27 is installed on the servo motor 17. In this way, the rotational movement of the motor 17 is transmitted to the motor barrel 29 through the synchronous toothed belt transmission mechanism, so that the hind limb board 14 follows the motor barrel 29 to rotate together.
 After conducting a large number of biological observation experiments, the inventor found that sea turtles have three basic forms of motion: horizontal linear motion, heave motion and steering motion. Therefore, the sea turtle robot of the present invention designs three motion schemes based on the motion characteristics of the biological prototype. Combined with Figure 3, Figure 4, and Figure 5, this horizontal linear motion implementation is hydrofoil swimming for the forelimbs; while the hind limbs perform auxiliary strokes when the linear motion is started, and then maintain horizontal gliding after the start. Taking the left forelimb as an example, the execution scheme of the forelimb hydrofoil swimming is: in the position shown in the figure, the motor 22 starts clockwise, and the rotation is transmitted to the motor sleeve 9 through the rotation of the spur gear pair. The motor sleeve 9 drives the forelimb board 1 to rotate counterclockwise around its axis (marked in the figure) together. The motor 22 stops after rotating at a certain angle, and the forelimb plate 1 rotates counterclockwise from the state shown in the figure to a certain angle with the surface of the paper, that is, as if the front edge of the forelimb of a sea turtle sinks. At this time, the motor 12 starts clockwise, through the bevel gear pair 2, the forelimb plate 1 starts to rotate around the axis of the small shaft 4 (marked in the figure), thus forming the forelimb plate 1 backward and downward against the water. . This is equivalent to when the forelimbs of a sea turtle are moving, the front edge is first sunk, and then flapped backward and downward, so that the water produces the same reaction force forward and upward. When the front limb 1 is flapped to the rear lower end approximately parallel to the housing 21, the motor 12 stops. At this time, it is as if the forelegs of a sea turtle are flapping to the lowermost end and cling to the body. Immediately after the motor 22 starts counterclockwise, it rotates the double angle of the first rotation and then stops, so that the forelimb plate 1 changes from the lower rear end to the lower front end, that is, from the sinking state of the front edge to the state of upturning the front edge. The motor 12 starts counterclockwise again. This process is like when the forelegs of a sea turtle flap to the lowest end, the front edge is first changed from sinking to the front edge upturning, and then flapping backward and upward to obtain the forward and downward reaction force to maintain the continuity of the force in the forward direction. When the front limb 1 is slapped to the upper rear end and approximately parallel to the housing 21 again, the motor 12 stops, and then the motor 22 rotates clockwise again to turn the front limb 1 to the upper front end, ready to pat the water backward and downward again. The following motors start and stop reciprocatingly in the above sequence to realize the forelimb plate 1 to reciprocate backwards and downwards and backwards and upwards, so that the turtle robot can obtain almost uninterrupted forward components. The whole movement process is like changing the upturning and sinking state of the front edge in time when the forelegs of a sea turtle flap to the end, and then flapping in the opposite direction to obtain a continuous forward component. The forelimb movement unit has two sets of symmetrical forelimb movement mechanisms, and the above-mentioned left-side mechanism can also complete the right-side mechanism. The left and right mechanisms operate at the same time to complete the hydrofoil swimming of the robot imitating the forelimbs of sea turtles. Taking the right hind limb as an example, the assisted stroke scheme for the hind limb when the robot starts linear motion is: in the position shown in the figure, the servo motor 17 first starts counterclockwise, and the real rotation shaft 30 follows the counterclockwise rotation through the synchronous toothed belt. Because the real shaft 30 is fixedly connected to the motor barrel 29, the motor barrel 29 and the hind limb board 15 begin to rotate counterclockwise around the axis of the real shaft 30 (marked in the figure), sending the hind limb board 15 to the starting point of the stroke, as if The hind limbs of the sea turtle are stretched forward before the stroke. When the hind limb board 15 turns to the foremost end, the motor 17 stops and the motor 41 starts clockwise, so that the hind limb board 15 starts to sink in the front edge. The motor 41 rotates 90° and then stops, the hind limb board 15 turns from the state shown in Figure 2 parallel to the paper surface to the perpendicular to the paper state, that is, if the hind limbs of a sea turtle turn from the horizontal state to the vertical state, it is ready to stroke with the largest water-facing area. . Then the motor 17 starts to run clockwise, the running speed is faster than counterclockwise, the hind limb board 15 starts to quickly stroke with the largest water-facing area, so that the robot obtains a forward reaction component, like the stroke of a turtle's hind limbs. When the motor 17 rotates 90° and then stops, the hind limb board 15 reaches the end position of the stroke, and the motor 41 starts counterclockwise again, so that the hind limb board 14 returns to the horizontal state. After that, the motor 17 rotates counterclockwise to slowly send the hind limb board 15 back to the starting point of the stroke with the smallest water-facing area, completing a stroke cycle, as if the turtle's hind limbs are sent parallel to the front of the water to the starting point of the stroke after the completion of the stroke. The following motors operate periodically according to the above steps to complete the periodic stroke of the hind limb board 15. Because the hind limb board 15 strokes backward with the largest water-facing area and returns with the smallest water-facing area, and the stroke speed is greater than the return speed, the forward reaction force it receives at this stage is greater than the backward water resistance. The left and right hindlimb mechanisms move at the same time, just like the two hindlimbs of a turtle paddling backwards, giving the robot forward thrust. When the robot reaches a certain speed, the controller will change the state of the hind limbs to the horizontal gliding state. The specific implementation plan is: the motor 41 turns the hind limb 15 from the current state back to the horizontal position, and the motor 17 sends the hind limb 15 to the end of the stroke. , That is, reach the end of the body, and then remain unchanged. The left and right hind limbs maintain such a glide posture after the robot's horizontal linear movement is stabilized, which is exactly the same as keeping the hind limbs at the back of the body to glide horizontally when a turtle swims horizontally.