Leo J. Stocco

Fast constrained global minimax optimization of robot parameters

A new global isotropy index (GII) is proposed to quantify the configuration independent isotropy of a robots Jacobian or mass matrix. A new discrete global optimization algorithm is also proposed to optimize either the GII or some local measure without placing any conditions on the objective function. The algorithm is used to establish design guidelines and a globally optimal architecture for a planar haptic interface from both a kinematic and dynamic perspective and to choose the optimum geometry for a 6-DOF Stewart Platform. The algorithm demonstrates consistent effort reductons of up to six orders of magnitude over global searching with low sensitivity to initial conditions.

Optimal kinematic design of a haptic pen

This paper investigates the performance demands of a haptic interface and shows how this information can be used to design a suitable mechanism. A design procedure, previously developed by the authors (1996), consisting of a global isotropy index and a discrete optimization algorithm, allows one to compare a range of geometric variables, actuator scale factors, and even different robot devices for optimum performance. The approach is used to compare the performance of three 6-DOF robots including two well-known parallel platform robots and a novel hybrid robot called the Twin-Pantograph in terms of their semi-dextrous workspaces and static force capabilities. Since the Twin-Pantograph yields the best results, its design is refined to address practical constraints and it is implemented as a haptic pen. The performance of the resulting design is analysed and presented.

A coarse-fine approach to force-reflecting hand controller design

A coarse-fine approach to the design of high fidelity haptic interfaces is proposed based on prior work and new psychophysics studies. The approach involves a fine-motion six-degree-of-freedom parallel Lorentz actuator mounted on a series/parallel coarse-motion stage and coupled through a compliant transmission. The frequency response of a simplified model is used to illustrate the advantages of the approach. The workspaces of three coarse-motion platforms are compared. A novel twin-elbow manipulator with all but one of the drive motors in the base is proposed for its simplicity and large workspace size.

Isotropy and actuator optimization in haptic interface design

A haptic interface controlled in impedance mode should present its user with a uniform force capability matching the human hand. This paper reviews a mechanism design methodology that maximizes a workspace-inclusive isotropy index. Force maximization in coreless or voice-coil motors is also considered in order to maximize haptic interface acceleration. Example designs of a planar 3-DOF haptic mouse, a 5-DOF haptic pen and a MagLev joystick are presented.

Wireless three-pad ECG system: Challenges, design, and evaluations

Electrocardiography (ECG) is a widely accepted approach for monitoring of cardiac activity and clinical diagnosis of heart diseases. Since cardiologists have been well-trained to accept 12-lead ECG information, a huge number of ECG systems are using such number of electrodes and placement configuration to facilitate fast interpretation. Our goal is to design a wireless ECG system which renders conventional 12-lead ECG information. We pro pose the three-pad ECG system (W3ECG). W3ECG furthers the pad design idea of the single-pad approach. Signals obtained from these three pads, plus their placement information, make it possible to synthesize conventional 12-lead ECG signals. We provide one example of pad placement and evaluate its performance by examining ECG data of four patients available from online database. Feasibility test of our selected pad placement positions show comparable results with respect to the EASI lead system. Experimental results also exhibit high correlations between synthesized and directly observed 12-lead signals (9 out of 12 cross-correlation coefficients higher than 0.75).

A wireless sensor system for motion analysis of Parkinson's disease patients

We describe the initial design, implementation and testing of a wearable sensor system employed for human motion analysis. Our proposed system is part of an ongoing investigation aimed at efficiently timing the self-administration of prescription drugs in Parkinsons disease patients by using wireless sensors to capture distinctive motion patterns that indicate the onset of dyskinesia lapses as the prescription drug wears off. Our prototype incorporates three pairs of accelerometer/gyroscope sensors, each connected to a wireless node equipped with an IEEE 802.15.4 radio. Sensor data are transmitted to a computer that is employed for visualization. We describe practical experience encountered during the initial development of our prototype, and outline the potential battery and bandwidth conservation benefits introduced by employing popular signal processing methods.

Integer dilation and contraction for quadtrees and octrees

Integer dilation and contraction are functions used in conjunction with quadtree and octree mapping systems. Dilation is the process of inserting a number of zeros before each bit in a word and contraction is the process of removing those zeros. Present methods of dilation and contraction involve lookup tables which consume considerable amounts of memory for mappings of large or high resolution display devices but are very fast under practical limits. A method is proposed which rivals the speed of the tabular methods but eliminates the tables, thereby eliminating the associated memory consumption. The proposed method is applicable to both dilation and contraction for both quadtrees and octrees.

On Spatial Orders and Location Codes

Spatial orders such as the Morton (Z) order, U-order, or X-order have applications in matrix manipulation, graphic rendering and data encryption. It is shown that these spatial orders are single examples of entire classes of spatial orders which can be defined in arbitrary numbers of dimensions and base values. Secondly, an algorithm is proposed which can be used to transform between these spatial orders and Cartesian coordinates. It is shown that the efficiency of the algorithm improves with a larger base value. By choosing a base value that corresponds to the available memory page size, the computational effort required to perform operations such as matrix multiplication can be optimized.

Demonstration of a novel wireless three-pad ECG system for generating conventional 12-lead signals

Wireless monitoring of a patients electrocardiogram (ECG) is a typical application in mobile healthcare area. Inspired by application of linear transformations to ECG signals obtained in a vectorcardiographic system, we propose the wireless three-pad ECG system (W3ECG). Signals obtained from these three pads, plus their placement information, make it possible to synthesize conventional 12-lead ECG signals. W3ECGs system-level design, pad placements and evaluations are presented in a separate paper. This paper details W3ECGs pad design, software implementation, and experimental studies.

Design and evaluation of a novel wireless three-pad ECG system for generating conventional 12-lead signals

Electrocardiography (ECG) is a widely accepted approach for monitoring of cardiac activity and clinical diagnosis of heart diseases. In order to make ECG systems portable, easy to setup, comfortable to patients and tolerant of artifacts, wireless single-pad ECG systems have been developed. To tackle the problems raised by wireless single-pad ECG systems, we propose an upgraded version, the wireless three-pad ECG system (W3ECG). W3ECG furthers the pad design idea of the single-pad approach. We add two more pads to the W3ECG to gain spatial variety of heart activity. Signals obtained from these three pads, plus their placement information, make it possible to synthesize conventional 12-lead ECG signals. We provide one example of pad placement and evaluate its performance by examining ECG data of four patients available from online database. Feasibility test of our selected pad placement positions show comparable results with respect to the EASI lead system. Experimental results also exhibit high correlations between synthesized and directly observed 12-lead signals (9 out of 12 cross-correlation coefficients higher than 0.75).