Fast Graspability Evaluation (FGE) has been proposed as a method for detecting grasping positions on objects and is now being used for industrial robots. FGE uses convolution of hand templates with regions on the target object to estimate the optimum grasping posture. However, the hand opening width and rotation angles must be set with high resolution to achieve highly accurate results and the computational load is high. To address that issue, we propose a method in which hand templates are represented in compact form for faster processing by using singular value decomposition. Applying singular value decomposition enables hand templates to be represented as linear combinations of a small number of eigenvalue templates and eigenfunctions. Eigenfunctions take discrete values, but response values can be calculated with arbitrary parameters by fitting a continuous function. Experimental results show that the proposed method reduces computation time by two thirds while maintaining the same detection accuracy as conventional FGE for both parallel hands and three-finger hands.

Keypoint matching is used in a variety of tasks such as specific object recognition and panoramic image generation. Affine-SIFT (ASIFT) enables affine invariant matching by generating many affine transformation images of an input image. It describes the scale-invariant feature transform (SIFT) features of the generated image. However, ASIFT must perform multiple costly online computations for affine transformation. We represent an oriented FAST and rotated BRIEF (ORB) descriptor in a linear filter subjected to many affine transformations. We calculate the affine features by convolving the generated filter with the patch image. However, convolving the 19,200 filters generated by the affine transformation is inefficient. In order to reduce the convolution processing, the affine transformation filter is made compact by a factorization method. We built a 4-order tensor using the affine transformation filter. The 4-order tensor decomposes into the Tucker model. We reduce dimensions appropriately for each mode. In this way, we propose a compact and accurate feature description. Our evaluation experiments confirmed that the proposed method reduces the processing time to 19% while maintaining the same precision as singular value decomposition, which is the conventional method.

We propose a method for estimating multiple-hypothesis affine regions from a keypoint by using an anisotropic Laplacian-of-Gaussian (LoG) filter. Although conventional affine region detectors, such as Hessian/Harris-Affine, iterate to find an affine region that fits a given image patch, such iterative searching is adversely affected by an initial point. To avoid this problem, we allow multiple detections from a single keypoint. We demonstrate that the responses of all possible anisotropic LoG filters can be efficiently computed by factorizing them in a similar manner to spectral SIFT. A large number of LoG filters that are densely sampled in a parameter space are reconstructed by a weighted combination of a limited number of representative filters, called "eigenfilters", by using singular value decomposition. Also, the reconstructed filter responses of the sampled parameters can be interpolated to a continuous representation by using a series of proper functions. This results in efficient multiple extrema searching in a continuous space. Experiments revealed that our method has higher repeatability than the conventional methods.

T3D edge detection from a depth image is an important technique of 3D object recognition in preprocessing. There are three types of 3D edges in a depth image called jump, convex roof, and concave roof edges. Conventional 3D edge detection based on ring operators has been proposed. The conventional ring operator can detect three types of 3D edges by classifying the response of Fourier transforms. Since the conventional method needs to apply Fourier transforms to all pixels of a depth image, real-time processing cannot be done due to high computational cost. Therefore, this paper presents a fast and reliable method of detecting three types of 3D edges by using a decision tree. The decision tree is trained under supervised learning from numerous synthesized depth images and labels by capturing depth relations between candidate pixels and pixels on a ring operator to classify 3D edges. The experimental results revealed that the proposed method has 25 times faster than the conventional method. This paper also presents some examples of 3D line and 3D convex corner detection based on results obtained with the proposed method.

The ultimate goal of this study is to develop a method that can accomplish dexterous manipulation of various non-rigid objects by a robotic hand. In this paper, we propose a novel model-free approach using reinforcement learning to learn a shared control policy for dexterous telemanipulation by a human operator. A shared control policy is a probabilistic mapping from the human operator's (master) action and complementary sensor data to the robot (slave) control input for robot actuators. Through the learning process, our method can optimize the shared control policy so that it cooperates to the operator's policy and compensates the lack of sensory information of the operator using complementary sensor data to enhance the dexterity. To validate our method, we adopted a page turning task by telemanipulation and developed an experimental platform with a paper page model and a robot fingertip in simulation. Since the human operator cannot perceive the tactile information of the robot, it may not be as easy as humans do directly. Experimental results suggest that our method is able to learn task-relevant shared control for flexible and enhanced dexterous manipulation by a teleoperated robotic fingertip without tactile feedback to the operator.

When the FAST method for detecting corner features at high speed is applied to images that include complex textures (regions that include foliage, shrubbery, etc.), many corners that are not needed for object recognition are detected because FAST defines corner features on the basis of a 16-pixel bounding circle. To overcome that problem, we propose the Cascaded FAST that defines corners on the basis of similarity in terms of intensity, continuity and orientation in a broader range of areas (20, 16, and 12 pixel bounding circles). Also, cascading three decision trees trained by the FAST approach enables high-speed corner detection in which non-corners are eliminated early in the process. Furthermore, Cascaded FAST determines scale by using an image pyramid and determines orientation at high speed by using a framework for referencing surrounding pixels.