感測與通訊整合技術應用於無人機時，可使空中基地台同時為地面用戶提供無線連接，並透過回波訊號分析進行環境感測。然而，無線傳輸的廣播特性結合無人機的可視線傳播特性，使得在感測與通訊整合任務中傳輸訊號容易遭受被動竊聽。本文針對具備多個移動用戶與潛在竊聽者的無人機輔助感測與通訊整合系統，探討聯合路徑規劃和功率分配問題。我們將此優化問題描述為受限制馬可夫決策過程，以在傳輸速率、保密速率與能量消耗之間取得平衡。為克服現有安全軌跡設計中能量浪費或過度保守迴避的缺點，本文提出一種結合 Safe-TD3 的兩階段策略，稱為 TS-SafeTD3。在第一階段（感測階段），無人機不進行通訊傳輸，而是導航至以用戶為中心的位置，以提升初始覆蓋效率，同時滿足與潛在竊聽者的最小距離安全限制；在第二階段（感測與通訊整合階段），利用 Safe-TD3 在相同安全約束下聯合路徑規劃和功率分配，以最大化加權保密速率。模擬結果顯示，所提出的演算法能在多種操作條件下有效提升加權保密速率與能量效率，並維持極低的安全約束違反機率。;Integrated sensing and communication (ISAC) technology, when deployed on unmanned aerial vehicles (UAVs), enables aerial base stations to simultaneously provide wireless connectivity to ground users and perform environmental sensing through echo signal analysis. However, the broadcast nature of wireless transmission, combined with the line-of-sight (LoS) propagation characteristics of UAVs, increases the risk of passive eavesdropping on transmitted signals during ISAC missions. This paper investigates the joint trajectory design and power allocation (JTDPA) issue for UAV-enabled ISAC systems in environments with multiple mobile ground users and potential eavesdroppers. The proposed approach formulates the optimization problem as a constrained Markov decision process (CMDP), aiming to balance communication rate, secrecy rate, and energy consumption. To address the limitations of existing secure trajectory designs, such as unnecessary energy expenditure and overly conservative avoidance actions, we propose a two-stage (TS) strategy that incorporates the safe twin delayed deep deterministic policy gradient (Safe-TD3) algorithm, referred to as TS-SafeTD3. In the first stage (sensing stage), the UAV navigates toward a user-centric location without communication to enhance initial coverage efficiency, while satisfying the minimum-distance safety constraints with respect to potential eavesdroppers. In the second stage (ISAC stage), Safe-TD3 is employed to jointly optimize both trajectory and power allocation under the same safety constraints to maximize the weighted secrecy rate. Simulation results indicate that the proposed algorithm improves the weighted secrecy rate and energy efficiency under various operational conditions, while maintaining a low violation probability of the safety constraints.
