Robust Control Techniques Enabling Duty Cycle Experiments Utilizing a 6-DOF Crewstation Motion Base, a Full Scale Combat Hybrid Electric Power System, and Long Distance Internet Communications

The RemoteLink effort supports the U.S. Army\u27s objective for developing and fielding next generation hybrid-electric combat vehicles. It is a distributed soldierin- the-Ioop and hardware-in-the-Ioop environment with a 6-DOF motion base for operator realism, a full-scale combat hybrid electric power system, and an operational context provided by OneSAF. The driver/gunner crewstations rest on one of two 6-DOF motion bases at the U.S. Army TARDEC Simulation Laboratory (TSL). The hybrid power system is located 2,450 miles away at the TARDEC Power and Energy System Integration Laboratory (P&E SIL). The primary technical challenge in the RemoteLink is to operate both laboratories together in real time, coupled over the Internet, to generate a realistic power system duty cycle. A topology has been chosen such that the laboratories have real hardware interacting with simulated components at both locations to guarantee local closed loop stability. This layout is robust to Internet communication failures and ensures the long distance network delay does not enter the local feedback loops. The TSL states and P&E SIL states will diverge due to (1) significant communications delays and (2) unavoidable differences between the TSL\u27s powersystem simulation and the P&E SIL\u27s real hardware-inthe- loop power system. Tightly coupled, bi-directional interactions exist among the various distributed simulations and software- and hardware-in-the-Ioop components representing the driver, gunner, vehicle, and power system. These interactions necessitate additional adjustment to ensure that the respective states at the TSL and P&E SIL sites converge. This is called state convergence and ensures the dominant energetic states of both laboratories remain closely matched in real time. State convergence must be performed at both locations to achieve bi-directional, real-time interaction like that found on a real vehicle. The result is a distributed control system architecture with Internet communications in the state convergence feedback loop. The Internet communication channel is a primary source of uncertainty that impacts the overall state convergence performance and stability. Multiple control schemes were developed and tested in simulation. This paper presents robust control techniques that compensate for asynchronous Internet communication delays during closed loop operation of the TSL and P&E SIL sites. The subsequent soldier- and hardware-in-the-Ioop experiments were performed using a combination of nonlinear Sliding-mode and linear PID control laws to achieve state convergence at both locations. The control system development, performance, and duty cycle results are presented in this paper

Robust Control Techniques for State Tracking in the Presence of Variable Time Delays

In this paper, a distributed driver-in-the-Ioop and hardware-in-the-Ioop simulator is described with a driver on a motion simulator at the U.S. Army TARDEC Ground Vehicle Simulation Laboratory (GVSL). Realistic power system response is achieved by linking the driver in the GVSL with a full-sized hybrid electric power system located 2,450 miles away at the TARDEC Power and Energy Systems Integration Laboratory (P&E SIL), which is developed and maintained by Science Applications International Corporation (SAIC). The goal is to close the loop between the GVSL and P&E SIL over the Internet to provide a realistic driving experience in addition to realistic power system results. In order to preserve a valid and safe hardware-in-the-Ioop experiment, the states of the GVSL must track the states of the P&E SIL. In a distributed control system utilizing the open Internet, the communications channel is a primary source of uncertainty and delay that can degrade the overall system performance and stability. The presence of a cross-country network delay and the unavoidable differences between the P&E SIL hardware and GVSL model will cause the GVSL states and P&E SIL states to diverge without any additional action. Thus, two robust strategies for state convergence are developed and presented in this paper. The first strategy is a non-linear Sliding Mode control scheme. The second strategy is an H-infinity control scheme. Both schemes are implemented in simulation, and both schemes show promising results for state convergence in the presence of variable cross-country time delays

Internet Enabled Remote Driving of a Combat Hybrid Electric Power System for Duty Cycle Measurement

This paper describes a human-in-the-loop motion-based simulator interfaced to hybrid-electric power system hardware, both of which were used to measure the duty cycle of a combat vehicle in a virtual simulation environment. The project discussed is a greatly expanded follow-on to the experiment published in [1,7]. This paper is written in the context of [1,7] and therefore highlights the enhancements. The most prominent of these enhancements is the integration (in real-time) of the Power & Energy System Integration Lab (P&E SIL) with a motion base simulator by means of a “long haul” connection over the Internet (a geographical distance of 2,450 miles). The P&E SIL is, therefore, able to respond to commands issued by the vehicle’s driver and gunner and, in real-time, affect the simulated vehicle’s performance. By thus incorporating hardware into a human-in-the-loop experiment, TARDEC engineers were able to evaluate the actual power system as it responds to actual human behavior. After introducing the project, the paper describes the simulation environment which was assembled to run the experiment. It emphasizes the design of the experiment as well as the approach, challenges and issues involved in creating a real-time link between the motion-base simulator and the P&E SIL. It presents the test results and briefly discusses on-going and future work

Using naturally occurring tumours in dogs and cats to study telomerase and cancer stem cell biology

AbstractThe recently described cancer stem cell theory opens up many new challenges and opportunities to identify targets for therapeutic intervention. However, the majority of cancer related therapeutic studies rely upon rodent models of human cancer that rarely translate into clinical success in human patients. Naturally occurring cancers in dogs, cats and humans share biological features, including molecular targets, telomerase biology and tumour genetics. Studying cancer stem cell biology and telomere/telomerase dynamics in the cancer bearing pet population may offer the opportunity to develop a greater understanding of cancer biology in the natural setting and evaluate the development of novel therapies targeted at these systems

Simulation and parameter sensitivity studies of skid-steering and Ackerman steering on an eight-wheeled vehicle

A three degree of freedom vehicle dynamics model that includes longitudinal and lateral tire force models is described, including its implementation into the Matlab/Simulink simulation environment. The tire force models account for the effect of longitudinal slip as well as lateral slip angles, and the force characteristics are assumed to take the form commonly found for hard surface (non-deformable terrain) applications. The baseline model was developed for an eight-wheeled platform, and the model allows for simulation of either Ackerman or skid-steered configurations. A simple driver model is integrated with the vehicle model and allows control of the velocity and heading of the vehicle. Several common vehicle maneuvers including straight-line motion, constant radius turn, oval racetrack, and lane change are used to verify the model capability. The model was used to compare energy consumption of an Ackerman-steered vehicle and a skid-steered vehicle for the maneuvers described above. It was verified that skid steering consumed more energy than Ackerman steering for all maneuvers except for the straight-line maneuver. In addition, the model was used to examine the effects of varying several vehicle design parameters on energy consumption. The specific parameters analyzed include vehicle mass, aspect ratio, number of wheels, longitudinal weight distribution, and roll weight distribution. Results from this parameter sensitivity study can be used to make important design decisions early in the design cycle for eight-wheeled vehicles and other similar applications.Mechanical Engineerin