Multicriteria Intercept Guidance and Control

Autonomous guidance encompasses the process of formulating a strategy by which an object is directed to maintain a specific trajectory, even when confronted with non-ideal circumstances. Within the realm of aerospace engineering, these non-idealities may arise due to a multitude of factors, including turbulent gusts of wind, navigational anomalies, unpredictable changes in weather conditions mid-flight, and more. In a broader sense, when discussing guidance, we typically consider the interplay between an object, acting as a pursuer or interceptor, and a distinct objective, which is also called a target or an evader. The primary aim is for the pursuer to steadily approach the intended target as time progresses. In order to achieve this, the pursuer must engage with and interpret information gleaned from its surroundings, subsequently making informed decisions. It is also worth noting that the target, in most cases, is not stationary. Rather, it frequently exhibits mobility, which induces different challenges during guidance design.

Intercept guidance involves a combination of complex calculations, sensor inputs, and control algorithms to guide the interceptor toward the target with high precision and efficiency. Typically, it also requires accounting for various factors such as target motion, environmental conditions, interceptor capabilities, and engagement constraints. A high-level overview of intercept guidance incorporates:

  1. Target Acquisition
  2. Engagement Planning
  3. Navigation/Control
  4. Midcourse Corrections
  5. Terminal Guidance

Applications like aerial refueling, docking, waypoint and collision-free navigation, landing, and target capture often place terminal constraints on the trajectory of the vehicle in addition to the primary objective of guidance. The recent successful landing of the reusable rockets can be seen as one such application where the terminal constraint on the attitude of the rocket was critical for a successful landing. In particular, our research develops terminal guidance and control strategies for an interceptor to capture a target (whose defensive capabilities are either manifested through enhanced structural integrity or agility in its motion) by exploiting target vulnerabilities like radar deception and structural constraints. Our work considers various types of constraints in different interceptor-target engagements for strategic trajectory shaping, while accounting for imperfect measurements, aerodynamic parameter variations, and the effects of autopilot performance on mission success.

Terminal (Impact) Time Constrained Guidance and Control for One-to-One Engagements

One-to-one impact time guidance plays a crucial role in scenarios where precision, timing, and synchronization are paramount. By aligning the pursuer's trajectory with the target's path at a specific moment, our approach enhances the chances of a successful interception, reduces collateral damage, and maximizes mission effectiveness in time-sensitive operations. Our approach also enables accurate positioning, compensates for target evasion, and maximizes efficiency in both planar and three-dimensional engagements.

Interceptor-target engagement geometry in the inertial frame of reference.
Interception of a stationary target at various impact time values.
Interception of a non-stationary, non-accelerating target at various impact time values.

Selected Publications:

Cooperative Time Constrained (Salvo) Guidance and Control for Many-to-One Engagements

Our research addresses the problem of having a coordinated simultaneous target interception under various terminal and in-flight constraints. One-to-one engagements require individual control over the interception time for each interceptor, potentially necessitating pre-programmed impact times prior to launch. In such cases, communication among interceptors is typically absent, resulting in an open-loop system that may prove inefficient in ensuring simultaneous target capture. To address these limitations, our research has increasingly focused on cooperative guidance strategies capable of guaranteeing salvo behavior by precisely controlling the times of interception. The proposed cooperative strategies aim to synchronize the actions of multiple interceptors, enabling them to act in unison and effectively coordinate their time of interception. By synchronizing their interception times, the interceptors can exploit vulnerabilities of the adversary and maximize the probability of target interception.

Illustration of multibody 3D engagement geometry.
Engagement between $i$th interceptor and a stationary target.
2D cooperative simultaneous interception of a constant speed target.
3D leader-follower cooperative simultaneous interception of a stationary target.
3D leaderless cooperative simultaneous interception of a stationary target.

Selected Publications:

Integrated Guidance and Control with Terminal Constraints

Traditionally, the design of guidance strategies focused primarily on the kinematics of the engagement between the interceptor and the target, disregarding the dynamics of the interceptor itself. These designs operated under the assumption that the interceptor could instantaneously achieve the desired acceleration. However, in unexpected flight conditions, relying on an idealized response of the control loop dynamics could lead to the deterioration of such designs, as previous studies have highlighted. Therefore, it is pragmatic and practical to consider the interceptor's dynamics when designing efficient and implementable guidance strategies, especially when there are constraints on its trajectory. Moreover, integrating separate guidance and control loops into a cohesive single loop, which directly generates the fin deflections, can significantly enhance the endgame performance of the homing interceptor, and allow better adaptation to varying flight conditions.

Interceptor and target trajectories for various times of interception.
Interceptor's time-to-go profiles.
Interceptor's lead angle and lateral acceleration.
Interceptor's canard and tail deflections.
Fig: Integrated guidance and control for a single interceptor.
Cooperative simultaneous interception of a maneuvering target.
Cooperative simultaneous interception of a constant speed target.
Cooperative simultaneous interception of a stationary target.
Fig: Integrated guidance and control for cooperative simultaneous target interception.

Selected Publications: