Loose vs Tight coupling

Parent: SLAM Index Backlinks: Multisensor fusion Source: [Wu 2018 Image-based camera localization: an overview](wu 2018-image-based-camera-localization_-an-overview.md)

In loosely-coupled systems: all sensor states are independently estimated and optimized

• easier to process frame and IMU data
• less accurate/robust compared to tight coupling
• e.g. Integrated IMU data can be incorporated as independent measurements in stereo vision optimization
• e.g. Vision-only pose estimates are used to update an EKF so that IMU propagation can be performed

In tightly-coupled systems: all sensor states are jointly estimated and optimized

• more difficult to process frame and IMU data
• more accurate/robust compared to loose coupling