Pradeep Setlur

Nonlinear tracking control of kinematically redundant robot manipulators

In this short paper, we consider the nonlinear control of kinematically redundant robot manipulators. Specifically, we use a Lyapunov technique to design a model-based nonlinear controller that achieves exponential link position and subtask tracking. We note that the control strategy does not require the computation of positional inverse kinematics and does not place any restriction on the self-motion of the manipulator; hence, the extra degrees of freedom are available for subtasks (i.e., maintaining manipulability, avoidance of mechanical limits and obstacle avoidance). Experimental implementations on a redundant robot are also included to illustrate the performance of the proposed control law.

An advanced engine thermal management system: nonlinear control and test

Internal combustion engine thermal management system functionality can be enhanced through the introduction of smart thermostat valves and variable speed electric pumps and fans. The traditional automotive cooling system components include a wax based thermostat valve and crankshaft driven water pump. However, servo-motor driven valves, pumps, and fans can better regulate the engines coolant fluid flow to realize fuel economy gains and tailpipe emission reductions. To study these cooling system actuators, with accompanying nonlinear control strategy, a scale experimental system has been fabricated which features a smart valve, electric coolant pump, radiator with electric fan, and immersion heater. In this paper, mathematical models will be presented to describe the systems behavior. A nonlinear controller will then be designed for transient temperature tracking. Representative experimental results are presented and discussed to demonstrate the smart valves operation in maintaining the temperature within a neighborhood of the target value for various scenarios including highway mode, full power with load disturbance, and quick heat.

Nonlinear control of a continuously variable transmission (CVT)

Automotive engineers are continuously exploring various engine, transmission, and chassis technologies to increase overall vehicle performance, fuel economy, and safety. One promising powertrain concept is the continuously variable transmission (CVT), which offers a continuum of infinitely variable gear ratios between established minimum and maximum limits. This continuous gear ratio spectrum can increase the overall powertrain efficiency and eliminate the unwanted jerks associated with manual and automatic transmissions. Although basic CVT designs may have difficulty with high torque/low speed requirements, a power split continuously variable transmission configuration offers both fixed gearing and adjustable pulleys to satisfy driving demands. The effective control of the variable radius pulleys allows the designation of engine torque/speed to improve overall system performance for a given operating condition. In this paper, the fundamental components, configuration, and kinematics of a power split CVT will be briefly introduced. The problem of wheel speed (i.e., cruise) control of a CVT equipped vehicle will be considered. An innovative adaptive nonlinear controller will be designed to ensure asymptotic tracking of the desired wheel speed. Representative numerical results are presented and discussed to demonstrate the ability of the integrated CVT and engine controller in tracking the prescribed wheel speed.

An Adjustable Steer-by-Wire Haptic-Interface Tracking Controller for Ground Vehicles

The introduction of steer-by-wire system technology into ground transportation vehicles permits customization of the human-machine haptic interface to accommodate the drivers desired level of road ldquofeel.rdquo The ability to tune the steering systems dynamic behavior can potentially enhance the drivers overall performance and increase the vehicles safety. A nonlinear tracking controller is designed to ensure that the directional control steering assembly follows the operators commanded maneuvers at the driver interface. In addition, the controller provides the driver with tunable force feedback proportional to the reaction forces at the tire-road interface. Two control techniques are provided to guarantee that the corresponding tracking errors are asymptotically forced to zero. The first compensates for parametric uncertainty, whereas the second eliminates the need for torque measurements through the use of observers. Representative numerical and experimental results are presented to demonstrate the controllers performance for various driving scenarios.

Nonlinear tracking control of the VTOL aircraft

In this paper, we present a nonlinear tracking controller for the nonminimum-phase, underactuated model of a vertical take off and landing (VTOL) aircraft. Specifically, the controller is designed to ensure that the VTOL aircraft position/orientation tracks a reference signal generator. The controller ensures that the position/orientation tracking error can be exponentially forced into an arbitrarily small neighborhood around zero (i.e., globally uniformly ultimately bounded (GUUB) tracking).

Nonlinear control of a continuously variable transmission (CVT) for hybrid vehicle powertrains

Automotive engineers are continuously exploring various engine, transmission, and chassis technologies to increase overall vehicle performance, fuel economy, and safety. One promising powertrain concept is the continuously variable transmission (CVT) which offers a continuum of infinitely variable gear ratios between established minimum and maximum limits. This continuous gear ratio spectrum can increase the overall powertrain efficiency and eliminate the unwanted jerks associated with manual and automatic transmissions. Although basic CVT designs may have difficulty with high torque/low speed requirements, a hybrid power split continuously variable transmission configuration offers both fixed gearing and adjustable pulleys to satisfy driving demands. The effective control of the variable radius pulleys allows the designation of engine torque/speed to improve overall system performance for a given operating condition. In the paper, the fundamental components, configuration, and kinematics of a power split CVT are discussed. A suite of mathematical models is presented which includes the internal combustion spark ignition engine, clutch, transmission differential, and chassis dynamics. The problem of wheel speed control of a CVT equipped vehicle is considered. An adaptive nonlinear controller is designed to ensure asymptotic tracking of the desired wheel speed.

Nonlinear controller for automotive thermal management systems

The functionality of gasoline and diesel engine thermal management systems can be enhanced through the introduction of a smart thermostat valve and variable speed water pump. A nonlinear tracking controller is presented in this paper for advanced thermal management systems applicable to ground vehicles. Specifically, the controller is designed to ensure that the engine temperature follows a desired temperature trajectory which may be prescribed based on operating conditions. Further, the heat rejected from the system at the radiator is controlled by adjusting the radiator fans speed. The controller ensures that the engine temperature tracking error is asymptotically forced to zero while compensating for the unmeasurable heat input from the engines combustion process.

A hardware-in-the-loop and virtual reality test environment for steer-by-wire system evaluations

A high precision, cost effective, experimental hardware-in-the-loop steer-by-wire test environment is presented and discussed to support engineering and psychology studies. In this project, a suite of chassis models and nonlinear control algorithms are developed and validated, as well as various human-machine interface design issues investigated. This paper provides an overview of the real time steering simulator which has been created to facilitate the comparison and evaluation of vehicle and steering system control strategies in a repeatable manner. The insertion of novel driver input devices, with adjustable force feedback, permits the study of the human-vehicle interface. The remote operation and/or supervision of semi-autonomous or autonomous vehicles can be studied using a human-in-the-loop system to provide insight into the relative importance to the driver of various vehicle parameters.

Nonlinear tracking controller design for steer-by-wire automotive systems

In this paper, a continuous time-varying tracking controller is designed for a steer-by-wire system in a automotive vehicle to ensure that the vehicles position/orientation follow that of a reference generator. The tracking error is globally and exponentially forced to a neighborhood about zero that can be made arbitrarily small (i.e., globally, uniformly and ultimately boundedness). The result is facilitated by transforming the system into a flat input-state system and then fusing a filtered tracking error transformation with the dynamic oscillator design. We also illustrate that the proposed tracking controller yields a globally, uniformly and ultimately bounded result for the regulation problem.

Power Split CVT Modeling With Spool Valve Actuation

New stringent emission regulations are requiring automotive engineers to develop vehicles featuring multiple energy sources and innovative drivetrain components. One such innovation is the continuously variable transmission (CVT) which offers a continuum of variable gear ratios for greater efficiency and elimination of unwanted jerks in comparison to fixed gear transmissions. The power split CVT configuration offers both fixed gearing and adjustable pulleys to satisfy the torque/speed demands. Spool valves regulate the hydraulic fluid to actuate the CVT’s primary and secondary sheaves for gear ratio manipulation based on the belt’s tension requirements. To fully support the evaluation of various powertrain configurations and control algorithms, a design tool must be developed which characterizes the complete powertrain system. In this paper, a power split CVT will be mathematically modeled and analyzed. Dynamic models will be introduced for the transmission, driveline, and chassis with attention focused on the CVT pulleys and hydraulics. Representative numerical results will be presented and discussed to quantify the performance of the power split CVT and sheave actuation for prescribed driving maneuvers.Copyright