Title: Autonomous Mobility Improvements of Hybrid Electric 4x4 with Controllable Power Transmitting Unit
Bringing vehicle autonomy to the level of its driveline system means that the autonomous vehicle has the capability to autonomously control the distribution of power between its driving wheels. A vehicle can therefore improve mobility by autonomously redistributing wheel power. For this implementation, vehicle mobility must first be quantified by suitable mobility indices, derived from vehicle dynamics, to numerically show a wheel or vehicle is close to immobilization as well as evaluate the effect of mobility improvements on the vehicle velocity. A velocity-based mobility index combines wheel traction with velocity to maximize effectiveness of movement. Computer simulations demonstrate the potential to improve velocity by optimizing vehicle mobility of a 4x4 vehicle with a hybrid electric power transmitting unit. more »« less
Jesse Paldan, Vladimir Vantsevich
(, Proceedings of the 3rd International Conference of IFToMM Italy)
null
(Ed.)
Active driveline technologies allow vehicles to dynamically control power distribution among driving wheels to improve vehicle operational parameters that impact terrain mobility. Two 4x4 electrified drivelines are compared which provide a variable power split: a hybrid electric vehicle with a controllable power transmitting unit and a fully electric vehicle (FEV) with individual electric wheel drives. The individual e-drives have the potential to improve mobility when the left and right wheel terrain conditions are drastically different.
Vantsevich, Vladimir; Paldan, Jesse
(, 27th IAVSD Symposium on Dynamics of Vehicles on Roads and Tracks)
Electric vehicles with the wheels individually driven by e-motors have promising potential for improving performance through finer control over the power distribution among the wheels. Due to the absence of a mechanical driveline to connect the wheels to the transmission and engine, the virtual driveline system (VDS) is proposed as a conceptual framework to connect virtu-ally the individual electric motors and, thus, to optimize and analyze the dynam-ics and performance of vehicles. Conceptually, the VDS is based on vehicle-gen-eralized parameters (VGP), which are used in the VDS principle to establish re-lationships between VGPs and, thus, to manage the wheel power split and set up interactive/coordinated controls of the e-motors to optimize and improve energy efficiency, terrain mobility performance, maneuver, etc. Keywords: Vehicle Dynamics Theory, Modeling
Elliot, Joshua; Lines, Austin; Ray, Laura
(, Proceedings of the ISTVS 20th International and 9th Americas Conference)
This paper presents mobility modes and control methods for the SnoWorm, a passively-articulated multi-segment autonomous wheeled vehicle concept for use in Earth’s polar regions. SnoWorm is based on FrostyBoy, a four-wheeled GPS guided rover built for autonomous surveys across ice sheets. Data collected from FrostyBoy were used to ground-truth a ROS/Gazebo model of vehicle-terrain interaction for simulations on snow surfaces. The first mobility mode, inchworm movement, uses active prismatic joints that link the SnoWorm’s segments, and allow them to push and pull one another. This pushing and pulling of individual segments can be coordinated to allow forward motion through terrain that would immobilize a single-segment vehicle. The second mobility mode utilizes fixed links between SnoWorm’s segments and uses the tension or compression measured in these links as a variable to control wheel speeds and achieve a targeted force distributions within the multi-segment vehicle. This ability to control force distribution can be used to distribute a towed load evenly across the entire SnoWorm. Alternatively, the proportion of the load carried by individual segments can be increased or decreased as needed based on each segment’s available drawbar pull or wheel slip.
Lines, Austin; Elliot, Joshua; Ray, Laura
(, Proceedings of the ISTVS 20th International Conference and 9th Americas Conference)
This paper presents a design approach for rigid wheels operating in highly variable, deformable terrain to improve the mobility, reliability, and efficiency of an autonomous vehicle driving on snow. The longstanding Bekker-Wong theory of terramechanics is used as the basis for the design changes with the wide range of terrain parameters for snow serving as inputs to the models and bounds for the problem. Modifications to the wheel width and diameter are evaluated based on their impacts to the rover as a system, with their effects on torque and drawbar pull being weighed against the resultant modifications in component sizing, rover weight, and energy use. Other factors, not included in the Bekker-Wong models but studied in single-wheel testbed experiments, such as bulldozing resistance and the observed dynamic effects of slip-sinkage, were also considered in the design decisions for the new wheel. Finally, to test these theories and assess the mobility improvements of the new design in situ, a four-wheeled rover, FrostyBoy, was developed for the new wheels and trialed in unmodified snow. While qualitatively showing an improvement in mobility on the Greenland ice sheet, the tests also uncovered dynamic modes of immobilization, in low cohesion, low stiffness snow that are not accounted for in terramechanics theory and require further investigation for trafficability to be maintained in all snow conditions.
Kannapiran, Shenbagaraj; Berman, Spring
(, 2020 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS))
null
(Ed.)
The Go-CHART is a four-wheel, skid-steer robot that resembles a 1:28 scale standard commercial sedan. It is equipped with an onboard sensor suite and both onboard and external computers that replicate many of the sensing and computation capabilities of a full-size autonomous vehicle. The Go-CHART can autonomously navigate a small-scale traffic testbed, responding to its sensor input wiwithth programmed controllers. Alternatively, it can be remotely driven by a user who views the testbed through the robot's four camera feeds, which facilitates safe, controlled experiments on driver interactions with driverless vehicles. We demonstrate the Go-CHART's ability to perform lane tracking and detection of traffic signs, traffic signals, and other Go-CHARTs in real-time, utilizing an external GPU that runs computationally intensive computer vision and deep learning algorithms.
Vantsevich, Vladimir, and Paldan, Jesse. Autonomous Mobility Improvements of Hybrid Electric 4x4 with Controllable Power Transmitting Unit. Retrieved from https://par.nsf.gov/biblio/10214005. Proceedings of the 2020 USCToMM Symposium on Mechanical Systems and Robotics .
Vantsevich, Vladimir, & Paldan, Jesse. Autonomous Mobility Improvements of Hybrid Electric 4x4 with Controllable Power Transmitting Unit. Proceedings of the 2020 USCToMM Symposium on Mechanical Systems and Robotics, (). Retrieved from https://par.nsf.gov/biblio/10214005.
Vantsevich, Vladimir, and Paldan, Jesse.
"Autonomous Mobility Improvements of Hybrid Electric 4x4 with Controllable Power Transmitting Unit". Proceedings of the 2020 USCToMM Symposium on Mechanical Systems and Robotics (). Country unknown/Code not available. https://par.nsf.gov/biblio/10214005.
@article{osti_10214005,
place = {Country unknown/Code not available},
title = {Autonomous Mobility Improvements of Hybrid Electric 4x4 with Controllable Power Transmitting Unit},
url = {https://par.nsf.gov/biblio/10214005},
abstractNote = {Bringing vehicle autonomy to the level of its driveline system means that the autonomous vehicle has the capability to autonomously control the distribution of power between its driving wheels. A vehicle can therefore improve mobility by autonomously redistributing wheel power. For this implementation, vehicle mobility must first be quantified by suitable mobility indices, derived from vehicle dynamics, to numerically show a wheel or vehicle is close to immobilization as well as evaluate the effect of mobility improvements on the vehicle velocity. A velocity-based mobility index combines wheel traction with velocity to maximize effectiveness of movement. Computer simulations demonstrate the potential to improve velocity by optimizing vehicle mobility of a 4x4 vehicle with a hybrid electric power transmitting unit.},
journal = {Proceedings of the 2020 USCToMM Symposium on Mechanical Systems and Robotics},
author = {Vantsevich, Vladimir and Paldan, Jesse},
editor = {null}
}
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