Cooperative Workspace Research Articles

OPTIMAL GRASPING STRATEGY OF SPACE TUMBLING TARGET BASED ON MANIPULABILITY

Due to the tumbling motion of the target, the dual-arm space robot to grasp a dynamic target is more challenging compared to a static target. Besides, optimization of the grasping strategy can improve the manipulability of the space robot to operate on the tumbling targets to ensure the success of the grasping mission. In this paper, a method for grasping strategy optimization is proposed based on the manipulability evaluation. When the dual-arm space robot cooperatively grasping a target, the dual-arm end-effectors contact the target simultaneously and a closed kinematics chain is formed. As a result, the formation of the closed-chain constraint complicates the evaluation of the manipulability of the space robot. First, the kinematics and dynamics of a dual-arm space robot manipulating a target are analyzed in this paper. Following this, a cooperative workspace considering the closed-chain constraint is established, and a task compatibility based detumbling manipulability metric is analyzed. The established cooperative workspace contains both the position and the attitude information of the manipulated target in the task space, which can be used for the calculation of dexterity. Then, the optimal grasping points of the end-effectors to grasping a target are determined based on the global dexterity metric, as well as the optimal grasping configuration of the space robot to grasp a tumbling target is found based on the force task compatibility metric considering the field-of-view constraint of the camera and the velocity tracking constraint of the end-effectors to the tumbling motion of the target. Using the manipulability metrics to determine the grasping strategy can make full use of the coordination of both arms to increase the manipulability of the space robot to manipulate dynamic targets, and simulations are conducted using a 7 degree of freedom dual-arm space robot to verify the feasibility and effectiveness of the proposed grasping strategy.

Optimal grasping pose for dual-arm space robot cooperative manipulation based on global manipulability

This paper presents an approach to determine optimal grasping poses for dual-arm space robot cooperatively grasping an uncooperative satellite. Aiming at better manipulating the satellite after capture, it is necessary to plan properly grasping poses on the satellite for dual-arm end-effectors to maximize the manipulability of space robot. In this paper, global manipulability based on capability map is applied as the quality index to seek optimal grasping poses. First, the technique to generate cooperative workspace for a closed chain system is introduced fusing the workspace of each single-arm with self-collision avoidance. Second, several general manipulability indices, such as dexterity, manipulability measure and task compatibility, are extended to the entire cooperative workspace to construct capability maps. Next, global manipulability is evaluated for dual-arm space robot cooperative manipulation based on the capability maps. Following this, the optimal grasping poses among all feasible grasping poses on the satellite are obtained by the global manipulability. Finally, a simulation study is carried out to verify the feasibility of the proposed approach based on a redundant dual-arm space robotic system.

Mechanical Design and Modeling of a Manipulator Tool for a Compact Multiple-Tool Single Port Laparoscopic Robot Platform.

Laparoendoscopic single-site surgery (LESS) has been shown to reduce the invasiveness of surgery by requiring only one incision to access the abdominal cavity. However, single-site surgery integrating with a compact robotic surgical platform remains as a unique challenge. To address this challenge, we have designed a comprehensive robotic surgery platform that consists of three 6-DOF manipulators and a laparoscope camera can all be inserted into the operation field through a single 18 mm cannula holding by one 4 degrees of freedom light-weight supporting frame. Each dexterous manipulator is 5+1 degree-of-freedom (DOF), serially inserted and removable, and remotely driven by 12 actuation tendons and is composed of rigid links joined by hybrid flexure hinges. This paper introduces the compact multiple-tool single port laparoscopic robot platform for the first time. Details of the mechanical design of the trocar and manipulator including joint design and tendon routing are presented. The forward and inverse kinematics of the manipulator are also discussed along with an analysis and simulation of the cooperative workspace of two manipulators. A preliminary dynamic model of the manipulator was also constructed to study the effect of tendon-sheath friction forces at various joint configurations. Future work will illustrate the existing supporting frame mechanism for posing tools and trocar.

Haptic Cooperative Virtual Workspace: Architecture and evaluation

The Haptic Cooperative Virtual Workspace (HCVW), where users can simultaneously manipulate and haptically feel the same object, is beneficial and in some cases indispensable for training a team of surgeons, or in application areas in telerobotics and entertainment. In this paper we propose an architecture for the haptic cooperative workspace where the participants can kinesthetically interact, feel and push each other simultaneously while moving in the simulation. This involves the ability to manipulate the same virtual object at the same time. A set of experiments carried out to investigate the haptic cooperative workspace is reported. A new approach to quantitatively evaluate the cooperative haptic system is proposed, which can be extended to evaluate haptic systems in general.

What you say is what you see ? Interactive generation, manipulation and modification of 3-D shapes based on verbal descriptions

The advent of virtual reality (VR) introduced a paradigm for human-to-human communication in which 3-D shapes can be manipulated in real time in a new kind of computer supported cooperative workspace (CSCW) (Takemura and Kishino 1992). However, mere manipulation — either with 3-D input devices (e.g., the DataGlove™) or with spoken language (Mochizuki and Kishino 1991) — does not do justice to this new paradigm, which could prove to be revolutionary for human-to-human and human-to-machine — communication. This paper discusses the possibility of providing the means for VR-based CSCW participants not only to interactively manipulate, but also to generate and modify 3-D shapes using verbal descriptions, along with simple hand gestures. To this end, the paper also proposes a framework for interactive indexing of knowledge-level descriptions (Newell 1982, Tijerino and Mizoguchi 1993) of human intentions to a symbol-level representation based on deformable superquadrics (Pentland 1986; Horikoshi and Kasahara 1990, Terzopoulos 1991). This framework, at least, breaks ground in integration of natural language with interactive computer graphics.