Dynamic Simulation of Blood Flow Effects on Flexible Manipulators During Intra-Cardiac Procedures on the Beating Heart

In this paper, we develop a numerical mixed flexible-rigid body model to take into account the effects of the external disturbances acting on a flexible manipulator secondary to the oscillatory transmitral blood flow in the left ventricle. The manipulator is made of a flexible rubber-like material to further extend the surgical robotic-based catheters’ degrees of freedom and steer-ability in beating-heart prosthetic aortic valve implantation procedure. Along with the developed numerical model, a detailed description of the catheter’s mechanical architecture and the actuation system is also provided. Necessity of employing such a model for the designed system is clearly justified using simulation studies.

Mixed H2/H∞ Observer-Based LPV Control of a Hydraulic Engine Cam Phasing Actuator

In this paper, a series of closed-loop system identification tests was performed for a variable valve timing cam phaser system on a test bench to obtain a family of linear models for an array of engine speeds and oil pressures. Using engine speed and oil pressure as the system parameters, the family of linear models was translated into a linear parameter varying (LPV) system. The engine speed and oil pressure can be measured in real-time by these sensors equipped on the engine, thus allowing their use as scheduling parameters. An observer-based gain-scheduling controller for the obtained LPV system is then designed based on the numerically efficient convex optimization or linear matrix inequality (LMI) technique. Test bench results show the effectiveness of the proposed scheme.

Design and Implementation of an Ionic-Polymer-Metal-Composite Aquatic Biomimetic Robot

Smart materials have been used in various applications. In this paper, a walking robot with six two-degree-of-freedom (2-DOF) legs made of ionic polymer metal composite (IPMC) is designed and implemented. Each leg can work as both a supporter and a driver, closely mimicking a real insect. To support and drive the robot, thicker (around 1 mm in thickness) IPMC strips were fabricated and used, and a 0.2-rad/s square wave is given as an input signal. The IPMC strips exhibit better performance in response to the square wave (8 mm) than sawtooth (4 mm) and sinusoidal (6 mm) waves in deflection. By applying this input signal in sequence, all the IPMC strips bend and walk in the form of six legs. In addition, thin magnet wires were used to supply power to each strip to prevent from confining the motion of our robot. Six lower legs are divided into two groups that work in the opposite directions to move the robot forward by turns. Upper legs are also divided into two groups to lift up their lower legs from making the robot to move back to the same place. The sizes of the IPMC strips and our robot (102 mm × 80 mm × 43 mm) were decided to exhibit better performance (0.5 mm/s) according to our tests.

Dynamic Model of Dual Clutch Lever-Based Electromechanical Actuator

The paper presents a dynamic model of a dual clutch lever-based electromechanical actuator. Bond graph modeling technique is used to describe the clutch actuator dynamics. The model is parameterized and thoroughly validated based on the experimental data collected by using a test rig. The model validation results are used for the purpose of analysis of the actuator behavior under typical operating modes.

Turbocharger Map Reduction for Control-Oriented Modeling

The gas exchange process in a modern diesel engine is generally modeled using manufacturer-provided performance maps that describe mass flows through, and efficiencies of, the turbine and compressor. These maps are typically implemented as look-up tables requiring multiple interpolations based on pressure ratios across the turbine and compressor, as well as the turbocharger shaft speed. In the case of variable-geometry turbochargers, the nozzle position is also an input to these maps. This method of interpolating or extrapolating data is undesirable when modeling for estimation and control, and though there have been several previous efforts to reduce dependence on turbomachinery maps, many of these approaches are complex and not easily implemented in engine control systems. As such, the aim of this paper is to reduce turbocharger maps to analytical functions for models amenable to estimation and control.

Myoelectric Torque Control of an Active Transfemoral Prosthesis During Stair Ascent

This paper presents experimental results of a myoelectric impedance controller designed for reciprocal stair ascent with an active-knee powered transfemoral prosthesis. The controller is modeled from non-amputee (normal) motion capture data, estimating knee torque with a linear two-state (stance/swing) impedance control form that includes proportional myoelectric torque control. The normal gait model is characterized by small stiffness and damping in both stance and swing, a low angle set-point in stance, a high angle set-point in swing, and proportional myoelectric control in stance but not swing. Clinical tests with a single unilateral transfemoral amputee indicate good performance of the controller; however, subject feedback suggests a reduction in the extensive myoelectric torque parameter and the need for constant, balanced myoelectric torque parameters in both stance and swing. Average prosthesis knee joint kinetics from a stairwell test using the amputee-tuned controller compare favorably with non-amputee gait data.

Classifications of Intentions for Controlling of a Multifunctional Knee-Ankle-Foot Orthosis

This paper describes motion intention classifiers which utilize reaction forces signals from heel and toe; and hip velocity information to predict subject’s intention. Those classifiers using Bayes method to predict (i) walk-to-stop, (ii) walking-speed-changing, and (iii) stop-to-motions. They are very accurate (most of them have accuracy rate higher than 90%) and a significant step in order to develop a multifunctional knee-ankle-foot orthosis.

Development of Diagnostic Algorithms for an Air Brake System: Theory and Implementation

In this paper, we consider the problem of designing an algorithm for estimating the stroke of a pushrod of the air brake system. The stroke of pushrod directly relates to the braking force available at the wheels and also affects the response time. The longer the stroke, the volume available for expansion is larger and correspondingly, the response is slower. The stroke depends on the clearance between the brake pad and the drum, which can vary due to variety of factors such as thermal expansion of drum and mechanical wear. Typical safety inspections of air brakes include the measurement of the stroke of the pushrod of each brake chamber. Regulations on trucks such Federal Motor Vehicle Safety Standard (FMVSS) 121 require the inspection to be carried out at 90 psi supply pressure and at full brake application. The evolution of the brake pressure depends on the stroke of the pushrod and the area of the treadle valve, which is controlled by the driver. The treadle valve meters compressed air from the supply reservoir to the brake chamber. The proposed scheme requires the measurement of pressure and a model for predicting the evolution of brake chamber pressure in response to full application of the brake (brake pedal is fully depressed). We experimentally corroborate the effectiveness of the proposed algorithm.

A Comparison Between Model-Based and Data-Driven Design of an Active Stability Control System for Two-Wheeled Vehicles

The design of an active stability control system for two-wheeled vehicles is a fully open problem and it constitutes a challenging task due to the complexity of two-wheeled vehicles dynamics and the strong interaction between the vehicle and the driver. This paper describes and compares two different methods, a model-based and a data-driven approach, to tune a Multi-Input-Multi-Output controller which allows to enhance the safety while guaranteeing a good driving feeling. The two strategies are tested on a multibody motorcycle simulator on challenging maneuvers such as kick-back and strong braking while cornering at high speed.

Iterative Learning Based Driver Input Synthesis for Evaluating Transient Diesel Soot Emissions

This paper presents the synthesis of driver inputs for evaluating diesel soot emissions using iterative learning control. Transient soot emissions from diesel engine vehicles are extremely sensitive to driver aggressiveness. Using closed-loop tracking controllers to follow a vehicle over a prescribed drive cycle usually do not account for the fact that drivers potentially adapt their driving styles to a given powertrain design. This work develops an algorithm producing driver input traces that significantly reduces the soot emissions for a given drive cycle, thus providing a consistent basis for evaluating the influence of powertrain design changes on soot emissions. Possible improvements are first explored using conventional optimal techniques and results are obtained using linear programming. It is then shown that a first-order PD-type iterative learning control based algorithm can deliver good performance, substantially reducing the total soot emissions at a fraction of the computational cost.