A method for the automatic verification of on-line handwritten signatures using both global and local features as described. The global and local features capture various aspects of signature shape and dynamics of signature production. The authors demonstrate that with the addition to the global features of a local feature based on the signature likelihood obtained from hidden Markov models (HMM) the performance of signature verification improves significantly. The current version of the program, has 2.5% equal error rate. At the 1% false rejection (FR) point, the addition of the local information to the algorithm with only global features reduced the false acceptance (FA) rate from 13% to 5%.

Three methods for on-line signature verification are discussed in this paper. They are based on statistical models of features that summarize different aspects of signature shape and the dynamics of signature production. Two of the methods are based on the feature statistics of genuine signatures only. Of these two methods, the simpler one using a Euclidean distance error metric was found to have superior performance when tested on a database of 919 genuine signatures and 330 forgeries. Using a procedure for selecting the individual best 10 out of 22 features, the Euclidean distance method correctly classified 99.5% of the genuine signatures, while rejecting 86% of the forgeries. The third method uses statistical properties of the forgeries as well as the genuine signatures to develop a quadratic discriminant rule for classifying signatures. On the basis of the database used in this study, this method was generally better than the simpler Euclidean distance method. At the same 99.5% acceptance of the genuine signatures, the method rejected 90% of the forgeries.

A control system for an autonomous robot cart designed to operate in well-structured environments such as offices and factories is described. The onboard navigation system comprises a reference-state generator, an error-feedback controller, and cart-location sensing using odometry. There is a convenient separation between the path guidance and control logic. Under normal operating conditions, the controller ensures that the errors between the measured and reference states are small. These errors only exceed set limits if the cart is malfunctioning. Major hardware failures can be detected in this way and failsafe procedures invoked. Results on the control system performance derived from a computer simulation of the cart and its operating environment, and from an experimental cart, indicate that the system can provide reliable, accurate, and safe operation.>

The use of lightweight flexible links in robot manipulators is desirable from the point of view of achieving robot arms which are faster and less expensive than the typical robot arms in use today. The disadvantages of light, flexible arms are (1) that they require a means for accurate end-point sensing and feedback to compensate for static load errors, and (2) that the feedback control system must also suppress the vibrational transients in the flexible arm during rapid arm movements. Since the arm load affects the transient and steady-state behavior of the flexible arm, the control strategy must be adaptive to load changes. This paper describes a method using an on-line estimator to provide periodic updates of load mass estimates to a parametric optimal controller which then adjusts the control gains to maintain the desired arm response. The method appears to offer a promising means for achieving rapid, smooth, and accurate motion of flexible robot arms under varying load conditions.

This paper describes a program for the simulation of the control logic and system dynamics of a robot arm having three Cartesian axes of motion plus two rotational axes of the wrist. The program was written in the C language and includes a fourth-order Runge-Kutta algorithm for the integration of the nonlinear differential equations for the individual axes. Validation of the program operation and evaluation of the many system parameters are also discussed. The simulated motion is compared and adjusted to fit experimental data on the actual arm motion. The results indicate that the simulation can be a useful and safe means for off-line testing of system changes and new control schemes.