Diagnosis of complex systems refers to the problem of identifying a breakdown or a failure based on an inspection, a control or a test. Monitoring such industrial complex systems is essential to schedule relevant maintenance actions. We consider an automotive subsystem to monitor: the brake system, because of its impact on the vehicles availability. Through a European project [1], data are acquired via in-vehicle communication protocols and additional sensors. This work aims at developing remote diagnostic and maintenance support tools driven by these data. Our approach combines an analytic model and detection techniques in order to monitor the brake system. We provide experimental results on vehicle data using two multivariate detection methods.

A pattern recognition approach for anomaly detection on buses brake system

A feature engineering framework for online fault diagnosis of freight train air brakes

A mathematical model of the mechanical subsystem of the trailer brake axle is described, which consists of a brake actuator, an application device and a drum brake. In the differential equation of motion, the total force from the mechanical subsystem reduced to the piston is described with a two-range linear-exponential model. The parameters of this model were determined using numerical identification, based on experimental, quasi-static curves of pressure in the air brake chamber as a function of pushrod displacement. An example of use of the mechanical subsystem mathematical model to simulate the dynamics of a single-axle agricultural trailer’s dual-line braking system with the Matlab- Simulink software is provided. The obtained results confirmed that the developed model is useful for testing transient processes in the air braking systems of tractor and truck trailers. The proposed experimental force curve determination method can also be used in the diagnostics of brake adjustment.

Experimental and numerical studies of mechanical subsystem for simulation of agricultural trailer air braking systems

Development of Diagnostic Algorithms for Air Brakes in Trucks. (August 2010) Sandeep Dhar, B.E., University of Mumbai; M. Tech., Indian Institute of Technology Bombay Co–Chairs of Advisory Committee: Dr. Swaroop Darbha Dr. K.R. Rajagopal In this dissertation, we focus on development of algorithms for estimating the severity of air leakage and for predicting the out-of-adjustment of pushrod in an air brake system of heavy commercial vehicles. The leakage of air from the brake system causes a reduction in the steady-state pressure in the brake chamber and an increase in the lag of the braking pressure response thereby increasing the stopping distance of the vehicle. Currently a presence of leak in the system is detected for the severities of leak that cause the reservoir pressure to drop below a threshold, such as, the leakage of compressed air due to rupture of the reservoir or of the hoses carrying the compressed air. The leakage of air is also possible due to several other reasons such as, cracks in the hoses, loose couplings between the hoses etc. The severities of leak, corresponding to such situations, do not lead to the reservoir pressure drop below the threshold; therefore, their presence remains undetected. For the detection and estimation of such severities of leak, a diagnostic scheme has been given and is based on a model developed for the mass flow rate of the leakage of air from the air brake system. Out-of-adjustment of the pushrod is the extension of pushrod beyond a predefined value and for safety concerns, an extension beyond this value is not desired.

Development of diagnostic algorithms for air brakes in trucks

Identification and estimation of parameters defining a class of hybrid systems

Brake systems in trucks are crucial for ensuring the safety of vehicles and passengers on the roadways. Most trucks in the US are equipped with S-cam drum brake systems and they are sensitive to maintenance. Brake defects such as leaks are a major cause of accidents involving trucks. Leaks in the air brake systems affect braking performance drastically by decreasing the maximum braking pressure and also increasing the time required to attain the same, thereby resulting in longer stopping distances. In this paper, we present a mathematical model for an air brake system in the presence of leaks with a view towards developing a diagnostic system based on this model in the near future. The model that has been developed builds on earlier research at Texas A&M University in which the pressure evolution in the brake chamber was determined as a function of the brake pedal input in the absence of any leaks in the air brake system. A leak may be characterized by its location and size. Since the connecting pipes are short, the location of the leak does not significantly affect the evolution in the brake pressure as much as its size. We provide a constitutive relationship for the leak and we estimated the associated parameter, namely, the “effective area” of the leak from the experimental data. The supply pressure and effective area of leak comprised the inputs to the model along with the displacement of the brake pedal (treadle valve plunger). We also provide a simple leak detection scheme and estimates of the severity of the leak in terms of the mass flow rate of leaking air based on the input measurements of brake pressure for a full application of the brake pedal and the supply pressure. This scheme can be implemented using a simple look-up table.

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Development of a model for an air brake system with leaks

Brake systems in trucks are crucial for ensuring the safety of vehicles and passengers on the roadways. Most trucks in the USA are equipped with S-cam drum brake systems and they are sensitive to maintenance. Brake deficiencies such as leaks and out-of-adjustment of the pushrod are a major cause of accidents involving trucks. Leaks in the air brake systems drastically affect braking performance by decreasing the maximum attainable braking pressure and also increasing the time required to attain the same, thereby resulting in longer stopping distances. Out-of-adjustment of the pushrod leads to loss of braking torque even if no leaks are present in the air brake system. In this paper, we present a mathematical model for an air brake system in the presence of leaks, with a view towards developing a diagnostic system for the air brake system based on the models. Additionally, we present a scheme that estimates the severity of leak in terms of the mass flow rate of air leaking from the air brake system to the ...

Srivatsan Ramarathnam

Papers

Development of a model for an air brake system with leaks

Development of a model for an air brake system with leaks and a scheme for the estimation of the steady-state pushrod stroke