# Analysis of Electromagnetic Field Characteristics of Wave Glider
## 2 Analysis of Motion Characteristics of Wave Glider
### Structure and Motion Characteristics of Wave Gliders  
The wave glider studied in this manuscript is shown in Figure 1, and is mainly divided into two parts: a surface mother ship and an underwater towing machine, with a distance of 7 m between the two parts. The surface mother ship consists of a sealed cabin surrounded by solar panels, floating materials, a control system, a battery, various sensor loads, and rechargeable batteries. The glider consists of a rotatable wing panel, a wing panel support frame, and a steering engine. The upper part in contact with water is non-metallic, the underwater towing machine is made of stainless-steel, and the propeller blades of the towing machine are made of carbon fiber. The wave glider relies on the mechanical energy of wave motion to convert it into forward thrust and maintain its motion characteristics. During its motion, the water wings on the wave glider rotate clockwise when descending and counterclockwise when ascending, generating hydrodynamic forces from the relative motion between the water wings and the ocean, thereby driving the underwater glider forward without being affected by the direction of the waves. The wave energy propulsion system is purely mechanical, and the propulsion device neither generates nor consumes electrical energy. The wave glider  
Figure 1: Schematic diagram of wave glider structure. has functions such as automatic navigation, position-keeping, and satellite communication monitoring. The platform is equipped with a satellite communication module, which can achieve real-time communication with the shore station and provide a continuous power supply to the load. During the motion of a wave glider, when the floating body on the water surface undergoes a heavy motion under the action of waves, the flexible connecting cable is affected by the combined force of the surface mother body and the underwater towing body. The underwater glider also generates a heavy through the umbilical cable, so it is in two states of tension and relaxation. As the waves rise on the surface of the ship, the flexible cables are tensioned, and the underwater towing machine moves upward and forward under the pulling force of the surface ship. When the surface of the ship descends with the waves, the flexible cables relax, and the underwater towing machine dives under its own gravity and glides forward under the push of the wing plates. (The underwater glider studied in this manuscript is shown in Figure 2). The wave glider has a powerful and flexible sensor carrying capacity. For the detection of underwater electromagnetic targets, it can be known from its structure and motion characteristics that the floating equipment of the wave glider floats on the water surface. Therefore, the underwater electromagnetic detection equipment is not suitable to be installed on the floating body of the water surface, and its movement relies on the movement of waves, resulting in significant noise generated by shaking; therefore, considering the installation of electric field sensors on underwater traction machines, there will be two aspects of electric field interference. First, the traction machine will induce an electric field. As the traction machine is made of bare stainless-steel material (excluding blades), the working depth of the traction machine is 7 m. During the tensioning and loosening process of the connecting cable, shaking-related electric field noise will be generated; the second is the electromagnetic field generated by the rotation of the steering engine. In order to maintain the heading, the steering engine will continuously adjust the rudder angle underwater, resulting in electromagnetic field interference. As shown in Figure 2, assuming the wave glider is moving along the \(x\) direction, the amplitude of its waves is \(a\), the magnetic inclination angle of the geomagnetic field \(F\) is \(\gamma\), and the angle between the glider's movement direction and the magnetic north is \(\theta\).