Author: kodlab

We present a working implementation of a dynamics based architecture for visual sensing. This architecture provides field rate estimates of the positions and velocities of two independent falling balls in the face of repeated visual occlusions and departures from the field of view. The practical success of this system can be attributed to the interconnection of two strongly nonlinear dynamical systems: a novel triangulating state estimator; and an image plane window controller. We detail the architecture of this active sensor, provide data documenting its performance, and offer an analysis of its soundness in the form of a convergence proof for the estimator and a boundedness proof for the manager.

We present a system for generation and recognition of oscillatory gestures. Inspired by gestures used in two representative human-to-human control areas, we consider a set of oscillatory motions and refine from them a 24 gesture lexicon. Each gesture is modeled as a dynamical system with added geometric constraints to allow for real time gesture recognition using a small amount of processing time and memory. The gestures are used to control a pan-tilt camera neck. We propose extensions for use in areas such as mobile robot control and telerobotics.

We report on our efforts to develop robot controller composition techniques in the context of dexterous “batting” maneuvers. A robot with a flat paddle is required to strike repeatedly at a falling ball until it is brought to zero velocity at a a specified position. The robot’s workspace is cluttered with obstacles that disconnect the freespace formed when the ball and paddle remain in contact – the machine is forced to “let go” for a time in order to bring the ball to the desired state. The controller compositions that we create will guarantee that a ball introduced in the “safe workspace” remains there and is ultimately brought to the goal. We believe that the developing systems discipline described here may be extended to build a variety of useful dexterous machines that are similarly single-minded in their pursuit of the user’s goal behavior and ability to surmount unanticipated perturbations along the way.

For more information: Kod*Lab

This paper reports on our present achievement toward the intelligent control of a boiler-turbine power-plant based on switching control scheme, recently revived by some active reports. To overcome strong nonlinearity emerging in load following operations of boiler-turbine power plants, which is not efficiently compensated by the conventional PI-based gain scheduling control, a neural-based nonlinear feed-forward switching control scheme is employed. Owing to its 2-degree freedom type installment in the control system and proper switching of nonlinear feed-forward control by monitoring contribution of inverse dynamics error to control error, effective suppression of nonlinearity is achieved.

We propose an event-driven approach to planning and control of robot assembly problems using ideas from non-cooperative game theory. We report on the results of an extensive simulation study for a very simple two degree of freedom case – the arrangement of disks on a plane by a disk shaped robot.

We report on our initial efforts to build robot feedback controllers that develop increased capability from simpler constituent controllers. Previous work with our three degree of freedom robot has resulted in a machine that exhibits various dynamically dexterous skills of superlative ability but very narrow behavioral scope. We focus here on the development of both a formalism and practice for the composition of constituent controllers. The composite should yield automatically purposive combinations of these skills that reach goals no one of the defining controllers could have achieved in isolation. The specific task we initially target, the “dynamical pick and place”, requires the robot to acquire balls that have been “randomly” thrown into its work space and set them safely at rest in a specified location. We present a brief overview of the constituent behaviors and a mechanism for their combination along with documentation of our preliminary empirical successes.

A simplified lossless model of the Raibert planar hopper is introduced for the purpose of analytically studying the control of forward velocity. A closed-form return map describing the robot’s state at the next hop as a function of that at the current hop is derived. The Raibert forward velocity controller is introduced and the fixed points of the closed loop system are characterized as well as the stability of these points. A new control law inspired by this analysis is introduced and compared with the Raibert control law.

In this paper we demonstrate that a passive vibration strategy can bring a 1 degree of freedom ball to a known trajectory from all possible initial configurations. We draw motivation from the problem of parts feeding in sensorless assembly. We provide simulation results suggesting the relevance of our analytical results to the parts feeding problem.

In this paper we demonstrate that a passive vibration strategy can bring a one-degree-of-freedom ball to a specified periodic trajectory from all initial conditions. We draw motivation from the problem of parts feeding in sensorless assembly. We provide simulation results suggesting the relevance of our analysis to the parts feeding problem.

This paper describes a simple visual servoing control algorithm capable of robustly positioning a three degree of freedom end effector based only on information from a stereo vision system. The proposed control algorithm does not require estimates of the gripper’s spatial position, a significant source of calibration sensitivity. The controller is completely immune to positional camera calibration errors, and we demonstrate robustness to orientation miscalibration through a series of simulations and experiments.

For more information: Kod*Lab