海况适应性对无人船实海域航行至关重要。为了揭示海况对无人船循迹性能的影响，以基于基准海况调校PID循迹控制的无人船为研究对象，建立三自由度动力学模型；在传统循迹精度评价的基础上，设计涵盖螺旋桨推进与舵机调节的控制耗能评价指标。以直航循迹为典型场景，仿真不同浪级干扰对无人船循迹精度与控制耗能的影响。结果表明，在高海况下，横向误差均方根较基准海况最大增加188倍，达158.207m，控制耗能增加3倍，评价指标达46.916kWh。量化直航循迹精度与控制耗能随浪级变化的规律，为无人船设计与控制提供参考。

Adaptability to various sea conditions is vital to unmanned surface vessels (USVs). This paper aims to reveal influence of sea conditions on tracking performance. The USV controlled by PID tuned for the baseline sea condition is studied. A three degree of freedom dynamic model is built， and a new evaluation index of control energy consumption accounting for propeller propulsion and steering mechanism operation is designed other than the conventional tracking accuracy. Simulation results demonstrate the variation trend of the tracking accuracy and control energy consumption with sea conditions under the typical straight line navigation case. The performance is significantly affected under high sea conditions， with root mean square error increasing 188 times up to 158.207m and control energy consumption increasing 3 times up to 46.916 kWh. The quantification of the tracking accuracy and control energy consumption with sea conditions provides reference for the design and control of USVs.