It has been known for some time that many tumors have a significantly different conductivity and permittivity from surrounding normal tissue. This high "contrast" in tissue electrical properties, occurring between a few kilohertz and several megahertz, may permit differentiating malignant from benign tissues. Here we show the ability of electrical impedance spectroscopy (EIS) to roughly localize and clearly distinguish cancers from normal tissues and benign lesions. Localization of these lesions is confirmed by simultaneous, in register digital breast tomosynthesis (DBT) mammography or 3-D mammograms.

This paper presents the development of a force/moment sensor named COSMO-II that can be used in the intuitive robot teaching of a six axis robot. A new principle of force/moment detection is presented that uses force sensing resistor as the transducer. The function of the COSMO-II sensor is to detect the force and moment about the principal axes of the the sensor coordinate system, so that the sensor information can be used for the intuitive robot teaching. The architecture and force/moment detection principle and the developed prototype sensor are describe. The performance of the sensor is evaluated and the results are shown. The sensor architecture is simple and can be implemented at low cost.

The teach pendant is the most widely used means of robot teaching at present. Despite the difficulties of using the motion command buttons on the teach pendant, it is an economical, robust and effective device for robot teaching tasks. This paper presents the development of a force/moment direction sensor named COSMO (COntact Sensor MOdule) that can improve teach pendant-based robot teaching. An intuitive robot teaching experiment with a six-axis commercial robot using the sensor is described, where the operator holds the sensor in his hand, and moves the robot by pushing, pulling and hoisting the sensor in the direction of the desired motion. No prior knowledge of the tool or world coordinate system is required. The function of the COSMO sensor is to detect the presence of forces and moments about the principal axes of the sensor coordinate system. The transducer used in the sensor is a micro-switch, and this intuitive robot teaching method can be implemented at very low cost.

In redundancy optimization problems related to cooperating manipulators, constraints should be considered for physical limits of the manipulators. The constraints have been imposed mostly in the form of linear inequality constraints, which lead to polyhedric feasible regions. We propose quadratic inequality constraints (QICs) which lead to ellipsoidal feasible regions to solve the optimization problem faster and to directly handle constraints on quadratic quantities. We investigate the effect of the use of QICs from the points of view of problem size and change of the feasible region. In order to efficiently deal with QICs, we utilize the dual quadratically constrained quadratic programming (QCQP) method. The proposed scheme and another well-known quadratic programming method are applied to numerical examples and compared with each other. The results show that the use of QICs makes it possible to make trade-off between optimality and fast computation capability and implements faster computation than the existing method.

In this paper, a formulation of joint disturbance torque is proposed for the independent joint controlled manipulators. The Lagrange Euler dynamic equation is examined, and joint disturbance torque is defined to be the joint torque components that are functions of joint position, velocity and acceleration. This definition includes all effects of joint coupling, varying effective inertia, and the gravity. The dynamic equation of motion for a 2-DOF planar robot is analyzed as an example. The explicit conditions for the minimum and maximum joint disturbance torques are identified, and the effect of link parameters on the joint disturbance torques is studied. As an application example, a solution of the optimal path placement problem is presented where, for a given straight line path segment, the location of the path in the robot workspace that results in a robot joint motion with the minimum joint disturbance torques is obtained.

A two-staged traffic control scheme, in which sets of candidate paths are prepared off-line prior to overall motion planning process, has been widely adopted for motion planning of mobile robots, but relatively little attention has been given to the application of the two-staged scheme to multiple automated guided vehicle systems (MAGVSs). In the paper, a systematic two-staged traffic control scheme is presented to obtain collision-free minimum-time motions of AGVs along loopless paths. The overall structure of the controller is divided into two tandem modules of off-line routing table generator (RTG) and an online traffic controller (OTC). First, an induced network model is established considering the configurational restrictions of guide-paths. With this model and a modified k-shortest path algorithm, RTG finds sets of k candidate paths from each station nodes to all the other station nodes off-line and stores them in the form of routing tables. Each time a dispatch command for an AGV is issued, OTC utilizes these routing tables to generate a collision-free minimum-time motion along a loopless path. Real-time computation is guaranteed in that the time-consuming graph searching process is executed off-line by RTG, and OTC looks for the minimum time motion among the k candidate paths. The traffic control scheme proposed is suitable for practical application in centralized MAGVS with zone blocking technique.

An efficient solution algorithm of the optimal load distribution problem with joint torque constraints is presented. A multiple robot system where each robot is rigidly grasping a common object is considered. The optimality criterion used is the sum of weighted norm of the joint torque vectors. The maximum and minimum bounds of each joint torque in arbitrary form are considered as constraints, and the solution that reduces internal force to zero is obtained. The optimal load distribution problem is formulated as a quadratic optimization problem in R/sup l/, where l is the number of robots. The general solution can be obtained using any efficient numerical method for quadratic programming, and in particular, for dual robot case, the optimal solution is given in a simple and efficient closed form so that the solution scheme can easily be utilized in the real time control of the dual robot coordination.

The conflict-free minimum-time motion planning problem in a multiple AGV system using zone control requires a traffic control scheme based upon a non-search technique, since the number of nodes contained in the network model for its guidepath is considerably large. The traffic control scheme presented in this paper partitions the overall task into two constituent tasks of path generation and traffic control. The Path Generator employs a k-shortest path search algorithm to construct path sets between all possible station node pairs. The path generation process is performed in off-line. Occupation times for each link are calculated and stored in a link occupation table which is represented from a link-oriented viewpoint. The traffic controller examines the link occupation table and dispatches AGVs in a conflict-free minimum-time path. The on-line motion planning operation is performed in real time.

The optimal load distribution for two cooperating robots is studied, and a solution approach utilizing a force ellipsoid is presented. The load distribution problem is formulated as a nonlinear optimization problem with a quadratic cost function. The effort exerted by the robots to follow the specified motion is defined to be the joint torque norm square, and the optimal solution minimizing the effort is obtained using the concept of the force ellipsoid and nonlinear optimization theory. Despite the presence of the joint torque constraints, the optimal solution is obtained almost as a closed form which requires small computation time. The proposed solution approach is illustrated and the internal force effect is studied using a numerical example.>