Precise Motion Compensation for Very High Resolution Repeat-Pass Airborne SAR Interferometry in the Presence of High Topography Variations

Motion compensation (MoCom) is one of the most critical processing steps for airborne SAR focusing. The high demands concerning the accuracy of motion compensation originate from applications like multibaseline polarimetric SAR interferometry, SAR tomography as well as differential SAR interferometry. During the recent years the airborne E-SAR system of DLR-HR has been operated mainly in these modes. For the E-SAR system an accurate and precise topography and aperture dependent MoCom algorithm (PTA) was developed. However, the future data supply for the development of novel SAR techniques and applications will be provided by the new F-SAR system offering improved spatial resolution, simultaneous acquisition in up to 3 frequency bands and in future also single-pass interferometry in X- and S-band. The objective of this thesis is to re-investigate the PTA approach for MoCom, in order to develop and implement an algorithm that overcomes the limitations established for the E-SAR system, and extending the correction to a 2D approach

Precise Motion Compensation for Very High Resolution Repeat-Pass Airborne SAR Interferometry in the Presence of High Topography Variations

Motion compensation (MoCom) is one of the most critical processing steps for airborne SAR focusing. The high demands concerning the accuracy of motion compensation originate from applications like multibaseline polarimetric SAR interferometry, SAR tomography as well as differential SAR interferometry. During the recent years the airborne E-SAR system of DLR-HR has been operated mainly in these modes. For the E-SAR system an accurate and precise topography and aperture dependent MoCom algorithm (PTA) was developed. However, the future data supply for the development of novel SAR techniques and applications will be provided by the new F-SAR system offering improved spatial resolution, simultaneous acquisition in up to 3 frequency bands and in future also single-pass interferometry in X- and S-band. The objective of this thesis is to re-investigate the PTA approach for MoCom, in order to develop and implement an algorithm that overcomes the limitations established for the E-SAR system, and extending the correction to a 2D approach

Development and Validation of a System for the Assessment and Recovery of Grip Force Control

The ability to finely control hand grip forces can be compromised by neuromuscular or musculoskeletal disorders. Therefore, it is recommended to include the training and assessment of grip force control in rehabilitation therapy. The benefits of robot-mediated therapy have been widely reported in the literature, and its combination with virtual reality and biofeedback can improve rehabilitation outcomes. However, the existing systems for hand rehabilitation do not allow both monitoring/training forces exerted by single fingers and providing biofeedback. This paper describes the development of a system for the assessment and recovery of grip force control. An exoskeleton for hand rehabilitation was instrumented to sense grip forces at the fingertips, and two operation modalities are proposed: (i) an active-assisted training to assist the user in reaching target force values and (ii) virtual reality games, in the form of tracking tasks, to train and assess the user’s grip force control. For the active-assisted modality, the control of the exoskeleton motors allowed generating additional grip force at the fingertips, confirming the feasibility of this modality. The developed virtual reality games were positively accepted by the volunteers and allowed evaluating the performance of healthy and pathological users