Low Order Optimal Filters for Linear Discrete-Time Systems

This paper treats of the linear discrete-time filtering problem where some elements of the measurement signal are free from noise. The main results are as follows : (i) A low order optimal filter is obtained by modifying the ordinary Kalman filter. (ii) Based upon the result (i), the structure of Tse-Athans' optimal minimal-order filter is made clear. (iii) Utilizing the result (i), the filtering problem with colored measurement noise is solved. This solution contains Bryson-Henrikson's result as a special case

On Adaptive Control Processes with Computing Time Delay

In the theory of R. Bellman's adaptive control processes, computing time to yield optimal control signal from data obtained during normal operation is ideally assumed to be zero. There will be, however, cases where the computing time delay may not be neglected. The subject of this paper is the optimal control policy for adaptive control processes in the case where certain computing time delay is assumed in advance. Functional equations to get such an optimal control policy are described in a fairly general form. These equations are also shown to be applicable to stochastic control processes and deterministic control processes. Two simple examples are presented to illustrate the application of the method

A Six-Axis Force Sensor with Three-Dimensional Cross-Shape Structure

A new six-axis force sensor is described. It has three pairs of elastic elements that are orthogonal to each other and cross at the center of the sensor. Each elastic element consists of a pair of thin parallel plates which is called a parallel plate structure. From the outputs of the strain gauges placed on the elastic elements, the six force components are obtained. This orthogonal structure, which is named the three-dimensional cross-shape structure, has the following merits. (1) The whole characteristic of the sensor is obtainable just by analyzing the force-strain relation of a pair of elastic elements on an axis, maing it simpler to design a sensor for a given specification. (2) The cross-coupling between the strain gauge outputs and the six force components can be made small. (3) It is easy to design a rigid sensor. A prototype sensor has been fabricated and it has ben shown that the measured characteristic coincides with the analysis based on the beam theory ; the cross-coupling is rather small, and the force-strain characteristics in all force directions are uniform. A few design considerations are also given

Dynamic Control of Multifingered Hands for Pivoting Operation

In this paper, we propose a dynamic control method of multi ngered hands for pivoting an object in contact with the environment. This pivoting operation is often observed when a human moves a large or heavy object such as furniture on the oor. Di erent from the conventional manipulation of the object by only ngers, the characteristics of the pivoting operation is that we can use the reaction force from the environment. By using this reaction force, we can expect the magnitude of the forces applied to the object by the ngers is smaller than the conventional manipulation of the object by only ngers. In this paper, taking this characteristics of the reaction force into consideration, we propose a dynamic control method for pivoting. To verify our approach, simulation results are also presented

Optimization of Grasping an Object by Using Required Acceleration and Equilibrium-Force Sets

In this paper, we search optimal grasp points and configurations of fingers for not only resisting an external force applied to a grasped object but also generating a desirable acceleration of the object. Based on the concept of required external force set, we define required acceleration and equilibrium-force sets. By using the sets, we formulate an optimization problem from the viewpoint of decreasing the magnitudes of the joint torques required to generate the required acceleration and equilibrium-force. We also show that we can solve the problem by using a branch-and-bound method. The validity of our approach is shown by numerical examples

Optimization of Grasping by Using a Required External Force Set

In this paper, we consider an optimization of grasping by using a required external force set. By using the set, we can not only deal with whatever a desired grasp is, such as force closure or equilibrium grasp, but also evaluate the magnitudes of the resistible external forces and moments. Then, we define an optimization problem from the viewpoint of decreasing the magnitudes of the contact forces required to resist the required external force, and show that we can solve the problem by using a branch-and-bound method. Lastly we present some numerical simulations to show the validity of our approach

Mechanics of Hybrid Active/Passive-Closure Grasps

In this paper, we discuss the directions of active and passive force closures in hybrid active/passive-closure grasps. We show the directions are orthogonal to each other. We also discuss the magnitudes of the internal forces in the manipulation of the object. In hybrid active/passive-closure grasps, there exist two kinds of magnitudes of internal forces. One is the magnitude of internal forces, which changes if the object moves and the geometry of the fingers changes. The other is the one which don’t change even when the object moves. We derive these two magnitudes

Design of a Desirable Trajectory and Convergent Control for 3-D.O.F Manipulator with a Nonholonomic Constraint

This paper is concerned with control of a 3 link planar underactuated manipulator whose most distal joint is unactuated. This system is known as a second order nonholonomic system. In a previous paper, we proposed a control law that guarantees the convergence of its state to a given desirable trajectory and to any desired final point. We also gave a design method of the desirable trajectory, but this method has a limitation on the location of the initial state. In the present paper, we propose a design method of a desirable trajectory that starts from any given initial point, converges to any given desired final point, and on the way passes through any given desired passing point that can be specifyed rather freely. By this new design method, we can derive a desirable trajectory that satisfies given requirements much better than the previous method