Browse Topic: Rollover accidents
ABSTRACT As a continuation of previous collaborative efforts between several US Army organizations and industry leaders which led to the procurement of a National Stock Number (NSN) for a near commercial-off-the-shelf winter tire/wheel assembly for the High Mobility Multipurpose Wheeled Vehicle (HMMWV), this study investigates a low-cost, postproduction modification known as ‘siping’ which may incrementally improve standard tires deployed on the Joint Light Tactical Vehicle (JLTV) in cold regions. Data from engineering tests will quantify performance differences as well as driver feedback from the 11th Airborne Division Soldiers in Alaska show moderate improvement from cutting razor-thin grooves known as ‘sipes’ on conventional winter tire sets. However, Army winter performance specifications developed in 2021 from HMMWV testing quantify greater available improvement to traction available, necessitating further development for winter traction in the JLTV family of tire sets as well as
ABSTRACT TARDEC researched head impact protective, energy attenuating materials for use in U.S. Army Ground System Vehicle (GSV) applications. The purpose of the project is to reduce potential head impact related mounted crew injuries and deaths which may occur during underbody blast, crash and rollover events. Commercial-off-the-shelf materials were evaluated for their energy attenuating performance. Exposed surface materials in combination with core material were also researched and evaluated. Baseline vehicle testing was conducted to understand the current head impact criterion. The results of this effort identified solutions which may potentially meet the needs of the Army to reduce head impact related injuries which may occur during crash, rollover and blast events. TARDEC used the knowledge gained from this project to create performance specification requirements for interior head impact protective components and materials for use in U.S. Army vehicles
ABSTRACT The need for up-armored vehicles has increased over the years. This has put a greater emphasis on suspensions that can provide improved ride and handling capabilities while facing the additional weight. One of the challenges with these vehicles traditionally has been increased likelihood of rollover. Increased rollover is due to high center of gravity, kinematics of the overloaded suspension, and the low damping that is needed to satisfy 6-Watt ride speed performance criteria. The Lord magneto-rheological (MR) suspension system addresses these issues by improving the ride quality and handling characteristics thereby increasing safety and mission effectiveness. During handling maneuvers, algorithms inside the controller unit apply corrective forces to minimize peak roll angle and peak roll rate. The benefit of this has been tested on a vehicle comparing the stock passive dampers to the MR dampers over NATO Lane change events. Furthermore, the controller has the capability to
ABSTRACT Teleoperated ground vehicles are an integral part of the U.S. Army and Marine Corps long range vision and a key transition technology for fully autonomous vehicles. However, the combination of marginally-stable vehicle dynamics and limited perception are a key challenge facing teleoperation of such platforms at higher speeds. New technologies for enhancing operator perception and automatically detecting and mitigating rollover risk are needed to realize sufficient safety and performance in these applications. This paper presents three rollover mitigation concepts for high speed teleoperation of heavy tactical vehicles, including model-predictive warning, negative obstacle avoidance, and reactive brake controls. A modeling and simulation approach was used to evaluate these concepts within the Autonomous Navigation Virtual Environment Laboratory (ANVEL). Vehicle models for both the M1078 cargo truck and RG-31 MRAP were used throughout concept evaluation over terrain ranging from
Letter from the Special Issue Editors
This SAE Standard establishes the maximum gradient rating during hopper discharge of self-propelled, driver-operated sweepers and scrubbers as defined by SAE J2130-1 and SAE J2130-2
The objective of this work is to capture the final deformed shape of a vehicle after a rollover caused by a corkscrew event (ramp). With this study, it will be possible to understand the vehicle structural behavior during this event and be able to improve the vehicle safety in this specific condition. For this proposal, it will be presented a virtual methodology using available commercial CAE tools and perform a crashworthiness analysis of the desired event. The first step is to capture the dynamic event through a Multibody analysis that represents the interaction among the vehicle tire, suspension components (Springs, Dampers, Jounce Bumper, Bushings, Stabilizer Bar etc.), vehicle structural stiffness, mass, center of gravity and inertias when exposed to a corkscrew standard ramp, that initiates the rollover event. This methodology will represent with fidelity all dynamic aspects of rollover event before the vehicle touches the ground. At this point, comparison of the analysis
This SAE Recommended Practice describes the test procedures for conducting quasi-static modular body strength tests for ambulance applications. Its purpose is to establish recommended test practices which standardize the procedure for Type I and Type III bodies, provide ambulance builders and end-users with testing procedures and, where appropriate, provide acceptance criteria that, to a great extent, ensures the ambulance structure meets the same performance criteria across the industry. Descriptions of the test set-up, test instrumentation, photographic/video coverage, and the test fixtures are included
The scope of this document is to provide an overview of the techniques found in the published literature for rollover testing and rollover crashworthiness evaluation at the vehicle and component levels. It is not a comprehensive literature review, but rather illustrates the techniques that are in use or have been used to evaluate rollover crashworthiness-related issues
Aiming at the problem of poor robustness after the combination of lateral kinematics control and lateral dynamics control when an autonomous vehicle decelerates and changes lanes to overtake at a certain distance. This paper proposes a trajectory determination and tracking control method based on a PI-MPC dual algorithm controller. To describe the longitudinal deceleration that satisfies the lateral acceleration limit during a certain distance of lane change, firstly, a fifth-order polynomial and a uniform deceleration motion formula are established to express the lateral and longitudinal displacements, and a model prediction controller (MPC) is used to output the front wheel rotation angle. Through the dynamic formula and the speed proportional-integral (PI) controller to control and adjust the brake pressure. Based on simulation to optimize the best lane change completion time coefficient at different longitudinal lane change speeds, the relationship between the vehicle collision
The tank truck has a wide range of application. When the liquid in the tank is not fully loaded, the lateral movement of the liquid in the tank will shift the center of gravity of the tank truck and make the vehicle less safe. It is easy to roll over when the tank truck is turning. This study combines the vehicle dynamic characteristics and geographic information, which gives the driver safe speed and safe braking distance tips before turning, to reduce the traffic accidents caused by driver's misjudgment. The dynamic model of the tank truck is established, through collecting the real-time information of the vehicle, the vehicle load and braking torque are calculated by the relevant dynamic model. The system needs to measure the deviation of the center of gravity in the tank truck movement process, and the deviation of the center of gravity has a great influence on the safety speed. The vehicle center of gravity position model is established, the sensor in the tank truck is used to
A single-vehicle crash involving an SUV led to the study of the failure of the anti-sway bar linkage and tire pressure and their relative effects on the handling characteristics of the vehicle. The SUV, having been involved in a rollover, was found with the anti-sway bar drop link disconnected from the suspension lower A-arm assembly. Also, after the crash, the tire pressure in the front tires on the subject vehicle was measured to be above the value specified by the SUV manufacturer; however, the pressure for one of the rear tires was measured to be roughly half of the SUV manufacturer’s recommended pressure. The other rear tire was deflated. The testing described herein addresses the question of what effects the anti-sway bar drop link disconnection or reduced rear axle tire pressure would have on the SUV’s pre-accident handling and driveability. A procedure for evaluating vehicle understeer and oversteer characteristics as specified by SAE J266 was employed to evaluate the yaw and
The counterbalanced forklift truck in the high-speed emergency steers and other extreme conditions, the single side of forklift is off the ground, which will cause a rollover, and the larger safety accidents are likely to occur and even endanger the safety of drivers. Aiming at the problem of judging the safety domain in the process of forklift driving, this paper proposes a strategy for dividing the forklift’s driving state on the basis of the zero-moment point. The relationship between the zero-moment point’s lateral component and the forklift’s support plane is used as the basis for division. The forklift rollover process is divided into a safe stage, a controllable danger stage, and a critical rollover stage. In the safe stage, the cylinder does not provide support force, and in the controllable danger stage, the cylinder support force is adjusted on the basis of the model predictive control algorithm to adjust the forklift. The cylinder can be controlled to provide maximum support
This SAE Recommended Practice describes the test procedures for conducting simulated dynamic lateral rollover restraint system tests for heavy truck applications. Its purpose is to establish recommended test procedures that will standardize restraint system testing for heavy trucks. Descriptions of the test set-up, test instrumentation, photographic/video coverage, and the test fixtures are included
The advancement in vision sensors and embedded technology created the opportunity in autonomous vehicles to look ahead in the future to avoid potential obstacles and steep regions to reach the target location as soon as possible and yet maintain vehicle safety from rollover. The present work focuses on developing a nonlinear model predictive controller (NMPC) for a high-speed off-road autonomous vehicle, which avoids undesirable conditions including stationary obstacles, moving obstacles, and steep regions while maintaining the vehicle safety from rollover. The NMPC controller is developed using CasADi tools in the MATLAB environment. The CasADi tool provides a platform to formulate the NMPC problem using symbolic expressions, which is an easy and efficient way of solving the optimization problem. In the present work, the vehicle lateral dynamics are modeled using the Pacejka nonlinear tire model. Further, a new algorithm is developed based on the box slope and box detection methods to
Full-scale instrumented vehicle dynamic brake testing of golf cars and Personal Transport Vehicles (PTVs) is presented and compared to the predictions generated by a previously described simple Matlab-based dynamic vehicle simulation program employing commonly used automotive vehicle modeling techniques. It is shown experimentally that many current golf car and PTV brake designs, which employ brakes on only the rear wheels, can lead to rollovers if the brakes are applied while traveling at high speed, on steep downhill slopes, and/or on low-friction surfaces and that this behavior is exacerbated by lateral forces such as steering inputs and road superelevation. After summarizing four rollover case studies, test-specific and parametric simulation results are compared to the results of full-scale on-site testing and are shown to provide accurate predictions of the resulting vehicle motions, including brake-induced yaw instability and subsequent rollover
With the increasing adoption of electric vehicles in India, autos are also getting in the electrification race with lighter lithium-ion batteries and motor replacing the bulkier engine and transmission. This trend has led to a lighter vehicle which in-turn gives better mileage figures but at the loss of dynamic stability of the vehicle making them very unsafe. The current auto-rickshaws are using delta configuration that is more prone to the rollover while cornering. The three-wheeled configuration vehicle is less dynamically stable than the normal four-wheeled configurations. While working on prototype vehicle for Shell Eco-Marathon Asia [7] pro and cons for both configurations for a three-wheeled vehicle were considered and tadpole configuration was found to be more stable and better than current delta configuration. The most common scenario that can happen with these vehicles in rural India is that the driver negotiates a corner with high speed and the Auto-rickshaw overloaded with
Tractor roll over is the most common farm-related cause of fatalities nowadays. ROPS (Roll-Overprotective Structures) are needed to prevent serious injury and death. It creates a protective zone around the operator when a rollover occurs. In India the ROPS is getting mandatory across all HP ranges except narrow track. In the present study states the customized ROPS application for configurable design such as Automated safety zone for all homologation standards, ROPS A0-D excel calculator for selection of material at concept stage and bolt calculator for selection of size. For the above applications below aspects need to consider such as Tractor weight, Rear housing mounting, Operator seat index position (SIP), Seat reference points (SRP) and all ROPS homologation standards. This ROPS application is to reduce the timeline, manual error and ensure the reliability of the modular optimal design for various platforms and variants. Nowadays it is important to perform configurable design at
In-phase rear-wheel steering, where rear wheels are steered in the same direction of front wheels, has been widely investigated in the literature for vehicle stability improvements along with stability control systems. Much faster response can be achieved by steering the rear wheels automatically during an obstacle avoidance maneuver without applying the brakes where safe stopping distance is not available. Sudden lane change movements still remain challenging for heavy articulated vehicles, such as tractor and semitrailer combinations, particularly on roads with low coefficient of adhesion. Different lateral accelerations acting on tractor and semi-trailer may cause loss of stability resulting in jackknifing, trailer-swing, rollover, or slip-off. Several attempts have been made in the literature to use active steering of semi-trailer’s rear wheels to prevent jackknifing and rollover. However, loss of stability in an articulated vehicle is usually caused by an oversteered tractor, and
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