Balancing of humanoid robot using contact force/moment control by task-oriented whole body control framework

Balancing control of humanoid robots is of great importance since it is a necessary functionality not only for maintaining a certain position without falling, but also for walking and running. For position controlled robots, the for-ce/torque sensors at each foot are utilized to measure the contact forces and moments, and these values are used to compute the joint angles to be commanded for balancing. The proposed approach in this paper is to maintain balance of torque-controlled robots by controlling contact force and moment using whole-body control framework with hierarchical structure. The control of contact force and moment is achieved by exploiting the full dynamics of the robot and the null-space motion in this control framework. This control approach enables compliant balancing behavior. In addition, in the case of double support phase, required contact force and moment are controlled using the redundancy in the contact force and moment space. These algorithms are implemented on a humanoid legged robot and the experimental results demonstrate the effectiveness of them.     

Robotic furniture assembly: task abstraction,motion planning,and control

Intelligent Service Robotics - This paper presents a novel framework for the complete assembly of a chair based on assembly instructions. First, the framework utilizes task templates and task...     

High-performance polymer light emitting diodes with interface-engineered graphene anodes

Recently, graphene-based organic light emitting diodes (OLEDs) were successfully demonstrated using graphene as anodes. However, the graphene electrodes have not been utilized for polymer light emitting diodes (PLEDs) yet, although the simpler device structure and the solution-based fabrication process of PLEDs are expected to be more advantageous in terms of time and cost. Here we demonstrate high-performance polymer light emitting diodes (PLEDs) with simple two-layer structures using interface-engineered single-layer graphene films as anodes. The single-layer graphene synthesized by chemical vapor deposition methods was transferred onto a glass substrate utilizing an elastic stamp, and its work function was engineered by varying the duration and the power of ultraviolet ozone (UVO) treatment. Thus, we were able to optimize the contact between silver electrodes and the graphene anodes, leading to the considerable enhancement of light-emitting performance.     

An Asynchronous Protocol for Release Consistent Distributed Shared Memory Systems

Distributed shared memory (DSM) systems provide a simple programming paradigm for networks of workstations, which are gaining popularity due to their cost-effective high computing power. However, DSM systems usually exhibit poor performance due to the large communication delay between the nodes; and a lot of different memory consistency models have been proposed to mask the network delay. In this paper, we propose an asynchronous protocol for the release consistent memory model, which we call an Asynchronous Release Consistency (ARC) protocol. Unlike other protocols where the communication adheres to the synchronous request/receive paradigm, the ARC protocol is asynchronous, such that the necessary pages are broadcast before they are requested. Hence, the network delay can be reduced by proper prefetching of necessary pages. We have also compared the performance of the ARC protocol with the lazy release protocol by running standard benchmark programs; and the experimental results showed that the ARC protocol achieves a performance improvement of up to 29%.     

Understanding makerspace continuance: A self-determination perspective

Makerspaces are informal physical spaces located in community settings or educational institutions where people immerse themselves in creative making. Makerspaces hold incredible potential for fostering essential skills needed for the future and are increasing in number worldwide. Previous research has identified many diverse makerspace initiatives and has demonstrated their potential, but few research has examined makerspace sustainability. Makerspace sustainability is a significant issue as diminished participation, activity, utilization, and retention limit its success. This study examines makerspace sustainability by understanding which factors influence makerspace continuance intention. This study proposes and empirically tests a conceptual framework based on self-determination theory to identify the motivations of makerspace users. An analysis of data collected from 121 South Korean makerspace users indicates that makerspace environmental support is significantly related to a makerspace user’s basic psychological needs. Those psychological needs positively impact intrinsic motivation, which ultimately influences makerspace continuance intention. This research has several implications for academics while recommendations are proposed that have immediate application for practitioners which are informed by the study results.     

Weighted hierarchical quadratic programming: assigning individual joint weights for each task priority

This paper proposes a novel method that computes the optimal solution of the weighted hierarchical optimization problem for both equality and inequality tasks. The method is developed to resolve the redundancy of robots with a large number of Degrees of Freedom (DoFs), such as a mobile manipulator or a humanoid, so that they can execute multiple tasks with differently weighted joint motion for each priority level. The proposed method incorporates the weighting matrix into the first-order optimality condition of the optimization problem and leverages an active-set method to handle equality and inequality constraints. In addition, it is computationally efficient because the solution is calculated in a weighted joint space with symmetric null-space projection matrices for propagating recursively to a low priority task. Consequently, robots that utilize the proposed method effectively show whole-body motions handling prioritized tasks with differently weighted joint spaces. The effectiveness of the proposed method was validated through experiments with a nonholonomic mobile manipulator as well as a humanoid.

     

Dielectric slab Rotman lens

A new form of a Rotman lens has been proposed for applications above 10 GHz, such as a collision avoidance radar. The proposed lens can be described as a dielectric slab fed by slot lines. The new form is expected to show lower loss and lower mutual coupling than the conventional Rotman lenses at higher frequency than 10 GHz. The prototype was implemented with nine beam ports and nine array ports. The measurements show that the mutual coupling can be lowered at higher frequency, and that the efficiency of the dielectric slab lens of about 30% can be obtained. We conclude that the dielectric lens is comparable to the conducting plate lens even though a spillover loss is presumed at frequency of the implementation.     

An active sensing strategy for contact location without tactile sensors using robot geometry and kinematics

In this study, we develop new techniques to sense contact locations and control robots in contact situations in order to enable articulated robotic systems to perform manipulations and grasping actions. Active sensing approaches are investigated by utilizing robot kinematics and geometry to improve upon existing sensing methods for contact. Compliant motion control is used so that a robot can actively search for and localize the desired contact location. Robot control in a contact situation is improved by the precise estimation of the contact location. From this viewpoint, we investigate a new control strategy to accommodate the proposed sensing techniques in contact situations. The proposed estimation algorithm and the control strategy both work complementarily. Then, we verify the proposed algorithm through experiments using 7-DOF hardware and a simulation environment. The two major contributions of the proposed active sensing strategy are the estimation algorithm for contact location without any tactile sensors, and the control strategy complementing the proposed estimation algorithm.     

HORSIC: An efficient one-time signature scheme for wireless sensor networks

One-time signature schemes are promising candidates for broadcast authentication, which is an essential security primitive in wireless sensor networks. This paper proposes HORSIC, an efficient one-time signature scheme for broadcast authentication in wireless sensor networks. Different from previous one-time signature schemes, HORSIC can reduce the public key size and signature size simultaneously at the cost of increased overhead in key generation and signature verification.     

Dance motion generation by recombination of body parts from motion source

In this paper, we propose an approach to synthesize new dance routines by combining body part motions from a human motion database. The proposed approach aims to provide a movement source to allow robots or animation characters to perform improvised dances to music, and also to inspire choreographers with the provided movements. Based on the observation that some body parts perform more appropriately than other body parts during dance performances, a correlation analysis of music and motion is conducted to identify the expressive body parts. We then combine the body part movement sources to create a new motion, which differs from all sources in the database. The generated performances are evaluated by a user questionnaire assessment, and the results are discussed to understand what is important in generating more appealing dance routines.