Combining Shape Completion and Grasp Prediction for Fast and Versatile Grasping with a Multi-Fingered Hand

Grasping objects with limited or no prior knowledge about them is a highly relevant skill in assistive robotics. Still, in this general setting, it has remained an open problem, especially when it comes to only partial observability and versatile grasping with multi-fingered hands. We present a novel, fast, and high fidelity deep learning pipeline consisting of a shape completion module that is based on a single depth image, and followed by a grasp predictor that is based on the predicted object shape. The shape completion network is based on VQDIF and predicts spatial occupancy values at arbitrary query points. As grasp predictor, we use our two-stage architecture that first generates hand poses using an autoregressive model and then regresses finger joint configurations per pose. Critical factors turn out to be sufficient data realism and augmentation, as well as special attention to difficult cases during training. Experiments on a physical robot platform demonstrate successful grasping of a wide range of household objects based on a depth image from a single viewpoint. The whole pipeline is fast, taking only about 1 s for completing the object's shape (0.7 s) and generating 1000 grasps (0.3 s).Comment: 8 pages, 10 figures, 3 tables, 1 algorithm, 2023 IEEE-RAS International Conference on Humanoid Robots (Humanoids), Project page: https://dlr-alr.github.io/2023-humanoids-completio

Optimized tunable Alvarez-Lohmann-lenses

In the late 1960s Alvarez and Lohmann independently suggested cubic phase plates as varifocal elements. A variety of different theoretical as well as experimental approaches have been discussed since. Today compact tunable optics is of specific interest e.g. in miniaturized optical systems. Recently developed fabrication technologies like diamond turning or milling nowadays enable the fabrication of higher order freeform surface profiles as implementation of efficient phase plates for an optimization of the imaging properties. We present a non-paraxial analysis of the imaging behavior of diffractive, refractive and hybrid Alvarez-Lohmann lenses with increased numerical aperture. Our analysis includes the influence of lateral focus shifts as well as monochromatic and polychromatic aberrations over the tuning range. Experimental results with phase plates fabricated by diamond milling and lithographic techniques will be presented

Chromatic aberration theory in modern metrology

Hyperchromatic systems are especially used in chromatic confocal metrology to measure distances, layer thicknesses, and object surfaces. The correction of the spherical aberration for all wavelengths is an essential requirement for the design of such systems. We present general techniques for the methodical design of hyperchromatic systems with large longitudinal chromatic aberration. The proposed techniques are applied to design a contact-free wall thickness measuring device. Large tilting angles of up to 20° in combination with an extra long measuring range of 18mm and a minimum working distance of 35mm require a high speed optical system. We discuss the problems arising during the design of a system that realizes high lateral resolution within the whole measuring range. Furthermore we demonstrate the optimization of optical systems which image different wavelengths onto different image planes

Integrated hybrid GRIN lenses

The use of microsystems technology for the manufacturing of integrated on-wafer optical systems often leads to shape restrictions of the optical surfaces. To achieve full performance in integrated free-space optical systems, light propagation has to be controlled in two directions: In the plane of the wafer and perpendicular to it. We present novel hybrid gradient index (GRIN) elements that allow for independent control of the optical function in these two directions. A functional GRIN layer structure for beam shaping perpendicular to the wafer plane is realized by a parameter variation of a plasma-enhanced chemical vapor deposition (PECVD) of silicon oxynitride. The optical functionality in the wafer plane can be achieved by a deep reactive ion etching process. The etched sidewalls in this case act as refractive or diffractive optical surfaces. Our work includes the discussion of this new hybrid concept, simulations, manufacturing as well as first experimental results

See-through near to eye displays: challenges and solution paths

Many consider see-through near to eye displays the successors to the smartphone and envision a multitude of mixed reality and augmented reality applications. The ideal optical imaging system for a see-through near to eye display combines a large field of view (≥ 100°) with a large pupil (≈ 20 mm) and is both lightweight and unobtrusive. In our contribution we first give an overview of challenges related to the design of see-through near to eye displays. Starting from the requirements of the human visual system, we then focus on two main performance parameters: field of view and aperture. These two parameters can be combined in a single parameter, the etendue. We show that the etendue of a see-through near to eye display is comparable to the etendue of lithography lenses and full frame camera lenses. To deliver the same etendue with a much lighter and more compact optical system is one of the main challenges of see-through near to eye displays. We discuss two possible solution paths: to increase the etendue close to the eye and to use foveated imaging concepts

Novel vision aids for people suffering from Age-Related Macular Degeneration

Degeneration (AMD), a disease that causes progressive damage to the central part of the retina. People suffering from AMD usually experience growing dark or blurred spots in the center of their vision which render them unable to read texts, to drive cars, or to recognise faces. Current vision aids for AMD patients are mainly based on the magnification and/or the redirection of the full field of view which will inevitably result in a loss of information at the outer parts of the field of view. In contrast, we present different optical principles for the redirection of the central part of the field while the loss of information at the boarders is kept to a minimum. Our focus is on highly integrated, nonelectric, spectacle-like systems. Possible principles include the field dependent displacement and magnification/reduction of the object information as well as a deliberately induced distortion. Our contribution includes the mathematical and optical modelling of the imaging setup, numerical simulations as well as the presentation of first experimental results

An optimization method for radial NURBS surfaces

We study the use of non-uniform rational B-splines (NURBS) for describing axially symmetric surfaces in the design of imaging optical systems. We suggest a representation using a base sphere with an additional NURBS curve. We present an optimization method for such surfaces based on the local structure of NURBS