This paper describe a method for high-speed compliance control by cooperation between an arm and a wrist body. To realize high-speed compliance control, it is necessary to reduce the endpoint inertia. The proposed method alleviates this problem by physically reducing the endpoint inertia, introducing a discreet wrist body, which is set up at the end of the arm, and by cooperative control between them. The wrist can generate a high-speed compliance because of its low inertia. However, the wrist's range of motion is restricted within a small range. We developed a method to solve this problem. The wrist can generate a desired compliance, and the arm expands the wrist's range of motion. Consequently the wrist-and-arm system can achieve compliant motion beyond the wrist's range of motion with multi degrees of freedom. We analyzed the behavior of the proposed wrist-and-arm system and compared it with the conventional method using force sensor feedback. This control method is implemented in a prototype system. We had experiments to evaluate our method by touching the cyclic displacement. We confirm the effectiveness of the cooperative control method by the results. They showed that our cooperative control method can expand wrist's range of motion.
We propose a method for sound source separation. The only informations we need for this method is temporal disparities of arrivals of sound sources at every pair of microphones. For this popose we linked our separating system to a localizing system. The localizing system can localize sound sources using temporal disparities at the onsets that are not mixed with ongoing partions of other sound sources. Several experiments were carried out in an anechoic chamber. We could separate two sound sources (speech sounds), located with azimuth difference of 38°, resulting in 25 dB average attenuation ratio, by a DSP system. The separable azimuth difference was more than 15°. And 5°localization error caused about 6 dB reduction in attenuation ratio.
When a body is under bilateral constraint, the constraint condition for the body is represented as homogeneous linear equations of velocity and force and their solution set for velocity is an orthogonal complement of that for force. In case of unilateral constraint, the condition is represented as homogeneous linear inequalities generally and their solution set for velocity is a dual polyhedral convex cone of that for force. However, no general method has been proposed yet for deriving such constraint condition automatically, when a body contacts another body in an arbitrary state. In this paper, we propose a general algorithm for deriving constraint of contact between bodies from geometric model of a body and working environment constraining it. The algorithm has been implemented in EusLisp. The algorithm is able to be applied in the case that a polyhedron with an arbitrary shape contacts another one in an arbitrary state and therefore very general. We believe it becomes a key technology for the analysis, planning and control of constrained motion and the assembly sequence planning.
Advanced Robot for the nuclear power plant is now increasing the complexity in comparison with Industrial Robot and its condition in use is severer than before; therefore its safety and reliability are of more and more importance at present. In this paper, for a robot health-care technology of Advanced Robot, a fault diagnosis method of robot servo systems is specified. The fault diagnosis method we developed, consists of the Co-operative Fault Diagnosis of Fault Tree Based Diagnosis and Pattern Diagnosis method. Fault Tree Based Diagnosis method is based on the knowledge of the robot designers and maintenance men. Pattern diagnosis method is based on the pattern comparison of the model and the real fault response. In the proposed Fault Tree Based Diagnosis, we have developed the Knowledge Complier and Fault Simulator for getting the diagnosis knowledge efficiently. In the proposed Pattern Diagnosis, we have developed the Fault Simulator for getting the model fault response with accuracy. Also, these actual examples of Co-operative Fault Diagnosis, Knowledge Complier and Fault Simulator are shown, and then their evaluations specified. In addition, the remained subjects of the Co-operative Fault Diagnosis method have been made clear in this paper.
This paper discusses transmission characteristics of tendon-sheath driving system typically used to actuate robotic finger joints, and also their effects on force control system. For a simple tendonsheath model, we first formulate the transmission characteristics with the newly introduced two physical parameters apparent tendon-stiffness and equivalent backlash. An interesting aspect is that apparent tendon-stiffness changes when the tendon is pulled or loosened, while tendon-stiffness itself keeps constant. This unexpected behavior is confirmed by simulations as well as experiments. We also consider the effect of apparent tendon-stiffness on force control precisely and show that the direction-dependent behavior ofapparent tendon-stiffness eventually brings about a direction-dependent response in the force control system.
A quadruped walking vehicle TITAN VI having a new leg mechanism is designed and manufactured. Objectives of design of TITAN VI are to walk on an ordinary staircase of 30 to 40 degrees, to constitute an active platform which assists manipulation in the stationary condition, and to walk at a high speed by using dynamic walk. The new mechanisms introduced in TITAN VI are, 1) prismatic joint leg mechanism which does not interfere with the steps of a staircase, and which performs a cylindrical coordinates motion with good energy efficiency, 2) an articulated body structure having node which copes with a steep staircase, 3) a vertical foot driving system having a dual mode transmission mechanism and the like. The detail of these mechanisms are discussed. The effectiveness of these considerations are verified by the walking experiment using the trial-manufactured TITAN VI.
In this paper, we study on hierarchical control structure of multi-D. O. F. manipulator to perform compliant manipulation on dynamic objects. We propose that in order to realize the real time fast computation of the joint control torques, it is better to calculate the joints angle terms with low sampling frequency at high level, and compute the lefted control torques including joints velocities and linear compensation with high sampling frequency at low level. Such hierarchical structure is demonstrated by the simulation of a 2-D. O. F arm pushing on a dynamic door. Simulation results also shows the effectiveness of the model matching method that was used in the linear force feedback compensator design, compared with impedance control.
The authors have been studying a mobile robot for inspection of the high voltage power transmission lines stretched between towers. The robot can run on a ground wire stretched on the top of the towers and go over the towers. In this paper, we propose a unique locomotive mechanism for the robot equipped with four crawlers, two arms with pulleys, and four actuators. It can go over the towers with stable state, and does not damage the towers and equipments on them. Geometrical conditions for the design of the mechanism and its details are described. A half scale model of the mechanism is constructed. It is confirmed by experiments that the mechanism can successfully go over the tower automatically with keeping static stability.
The problem of slip detection has to be explored so that an industrial robot may certainly grasp objects with the appropriate grasping force. Slip Sensors must be able to detect fine slip to be used for controlling grasping force. Slip sensors are classified into two types; tactile slip sensors and nontactile slip sensors. The tactile slip sensors must be pressed against the object surface. If the sensor is pressed with an insufficient force, it can't detect slip correctly. If the sensor is pressed with an excessive force, the object may be damaged. A method of nontactile slip detection have been proposed before. In this method, the sensor detects intensity of scattered light from an object surface at the position of fringes of the phenomenon of two-beam interference. In this paper, we describe development of a nontactile slip sensor using the method above mentioned. The slip sensor has features as follows; 1. NonTactile, 2. The fine slip can be detected by projecting a grating image on the object surface, 3. The sensor is miniaturized by using semiconductor laser and by assembling components of the sensor in one case.