Shankar Subramanian

Indian Institute of Technology Madras | IIT Madras · Department of Engineering Design

Even though diesel-powered Heavy Goods Vehicles (HGVs) are major contributors of greenhouse gas emission, HGV electrification is still in its infancy owing to various challenges. Costlier and heavier batteries and lack of charging infrastructure along long routes are the major bottlenecks in the realisation of HGV electrification for long-haul frei...

Passing Sight Distance (PSD) is pivotal for two-lane undivided highways, impacting their safety and operational performance. However, current PSD standards and models are based on simplistic assumptions and do not consider road characteristics and vehicle dynamic response. This study investigates the adequacy of PSD models in practice by comparing...

This paper presents solutions to challenges in using a low-density flash lidar for application to a heavy road vehicle Autonomous Emergency Braking (AEB) system. Low-density flash lidars are relatively new to the commercial market and are much less expensive compared to point-cloud lidars. However, due to their low angular resolution, it becomes ch...

This study introduces a novel approach for enhancing safety in Heavy Commercial Road Vehicles (HCRVs) by combining Rollover Prevention and Antilock Brake System. The primary focus is preventing rollovers through controlled differential braking while avoiding potential wheel lock. The study employs a 3-Degrees of Freedom (3-DoF) model-based strategy...

Global adoption of electric vehicles (EVs) faces many challenges such as range anxiety, high cost of EVs, and inadequate charging infrastructure. EV-sharing platforms resolve such concerns by setting up an optimal configuration for charging infrastructure and optimizing the charging decisions for depleted EVs. These platforms manage the vehicles’ f...

During the braking manoeuvre of a vehicle on a pavement, the mechanics associated with load transfer is complex due to the presence of slip, load shift between the front and rear axles, and development of longitudinal forces. The road profiles, braking intensity, truck mass, and speed during braking play a critical role here. This investigation rep...

An urban arterial can be considered a series of intersections, intermediate sections (defined as those that link intersections and mid-block areas), and mid-block sections. The intermediate section is characterized by varying speed characteristics at its entry and exit. A vehicle exiting the intersection and entering the intermediate section would...

Accurate bus travel time prediction in real-time is challenging, as numerous factors such as fluctuating travel demand, incidents, signals, bus stops, dwell times, and seasonal variations can affect travel time, a spatio-temporal variable. Literature that considered the spatio-temporal evolution of bus travel time adopting traffic flow theory-based...

When a road vehicle is subjected to combined cornering and emergency braking, it potentially has a greater risk of wheel lock followed by loss of steerability and/or undesired yaw motion. While an Anti-lock Braking System (ABS) is mandatory in many countries to avoid wheel lock, more attention is required to its combined cornering and braking perfo...

Heavy commercial road vehicle (HCRV) platoons are viable logistic solutions to freight movement. During long haul platoon operation, it is common to encounter roads of different gradients. This paper investigates the effect of brake fade phenomenon, which happens due to the continuous application of brake during downgrade operation on the string st...

Faults in the air brake system used in Heavy Commercial Road Vehicles (HCRVs) would adversely affect the vehicle’s dynamic performance, and hence their prompt detection is critical for vehicle safety. This paper first investigates the effect of air brake system faults through extensive hardware-in-loop experiments. These faults were observed to deg...

Heavy Commercial Road Vehicle (HCRV) platooning is a promising solution to meet increasing freight transportation demands. This paper applies the concept of Artificial Potential Functions (APF) to design a string stable controller, viz., Potential Function-based String Stable (PFSS) controller, for establishing stable HCRV platoons under various op...

This paper develops a novel algorithm for tracking closely-spaced road vehicles using a low-density flash lidar. Low-density flash lidars are recent to the automotive market and have attracted attention due to their low cost. However, these sensors have a poor angular resolution which makes tracking the lateral motion of targets challenging. One su...

The distress of asphalt pavements on horizontal curves can be relatively higher because of the lateral load transfer and the increase in lateral forces on vehicles during their cornering manoeuvre. In this study, the lateral load transfer in horizontal curves and its effect on pavement disstress is evaluated using a commercial vehicle dynamics soft...

Electrification of military vehicles offers the potential for extended stealth operation, enhanced vehicle performance, and onboard electric power. This study proposes a hybrid electric powertrain for a military tracked vehicle with hybrid energy storage (battery and capacitor) and multi-speed transmission. Initially, component sizing of the propos...

Knowledge of the tyre-road interface traction limit during braking of a road vehicle can drastically improve safety and ensure stable braking on varied road conditions. This study proposes an optimal reference slip algorithm that determines the road surface while the vehicle is braking, by implicitly tracking the traction limit. It presents wheel s...

The process of modelling vehicle motion in a road traffic environment requires the integration of trajectory generation with vehicle control. The steps involved here are generating a feasible trajectory based on the existing traffic and tracking the trajectory to control it with a steering angle input. Since the parameters of a physical system vary...

Dynamic prediction of queues and delays at signalized intersections utilize data obtained from automated traffic sensors as inputs for Intelligent Transportation Systems (ITS) applications. Errors are inevitable during automated data handling, especially when the traffic involved is heterogeneous and lacking in lane discipline. This paper presents...

Integration of heavy commercial road vehicle platooning concept and electric vehicle technology is a promising approach as far as sustainable freight transportation is considered. This article attempts to design a string stable controller for an electric heavy commercial road vehicle platoon by incorporating critical factors such as complete vehicl...

This research presents a rule-based Anti-lock Braking System (ABS) algorithm towards active vehicle safety in Heavy Commercial Road Vehicles (HCRVs). Wheel Slip Regulation (WSR) algorithms, that are constituents of an ABS, are typically either model-based or rule-based. Model-Based Algorithms (MBAs) utilise mathematical models that characterise veh...

In vehicles, wheel locking and associated instability issues can be prevented by regulating wheel brake torque during braking. In contrast with conventional vehicles, electrified vehicles have both friction and regenerative braking. Typically, pneumatic friction braking is used for Wheel Slip Regulation (WSR) in Heavy Commercial Road Vehicles (HCRV...

This paper presents a string stable controller for the autonomous operation of a platoon of Heavy Commercial Road Vehicles (HCRVs) in a connected environment. This study considers factors such as brake/powertrain actuator dynamics, resistive forces, tyre model and wheel dynamics, which are crucial during on-road operation of HCRVs. A nonlinear vehi...

Accurate fault diagnosis in air brake is crucial to reduce frequent brake inspection and maintenance in heavy commercial road vehicles. Existing model-based fault diagnostic schemes work well under limited vehicle operating conditions, which is insufficient for developing an on-board monitoring device. In this context, a learning-based fault identi...

This work proposes a methodical framework for emulating wheel lock in a brake dynamometer. In this study, the dynamic effects during braking, particularly load transfer, wheel slip, and tyre–road interactions, are subsumed into a single variable termed ‘equivalent inertia’ to replicate a wheel lock event. The variations of this variable were captur...

Performance enhancement of typically sluggish pneumatic brake actuators in Heavy Commercial Road Vehicles (HCRVs) is necessary for the efficacious operation of active safety systems. This study develops a robust Proportional Integral Derivative (PID) controller using the Kharitonov theorem for pneumatic brakes. To account for the inherent time dela...

Tractors are attached with function-specific implements with the help of an electro-hydraulic hitch system, to carry out various farm operations. Forces arising during travel with the lifted implement on uneven terrain, generate disturbance forces on the hitch system. In this study, the electro-hydraulic system was controlled such that the disturba...

An Antilock Braking System (ABS) is an Active Vehicle Safety System (AVSS) employed to prevent wheel lock in road vehicles. Wheel lock is undesirable as it may lead to loss of vehicle steerability and directional stability. These become critical in Heavy Commercial Road Vehicles (HCRVs) as unintentional yaw motion resulting from directional instabi...

Given the condition of mixed road traffic, few models exist that can predict the motion of a vehicle in it. Mixed road traffic can be defined as being both, lane indisciplined and heterogeneous. This study aims at developing a model that can analyze a given traffic condition, generate a safe trajectory and provide a control input to the vehicle to...

Regulation of heterogeneous traffic is a challenging task on urban roads, particularly those where traffic congestion is routinely encountered. In this paper, a model based traffic signal control scheme via state feedback controller is presented. An original contribution of this study is the use of area occupancy as the measurement variable, which...

Faults in an air brake system affect the performance of Heavy Commercial Road Vehicles (HCRVs). One of the major faults in the air brake system is the “out-of-adjustment”of pushrod due to excessive brake wear, which may cause a significant yaw angle deviation from the current path and an increase in stopping distance. Hence, this paper aims to desi...

This paper proposes a control scheme to use regenerative braking for Wheel Slip Regulation (WSR) in Heavy Commercial Road Vehicles (HCRVs). Typically, in HCRVs, WSR is achieved using pneumatic friction brakes. However, in electrified vehicles regenerative braking is available and this can be beneficial as electrical machines have higher bandwidth c...

Managing congestion in mixed traffic conditions, characterized by heterogeneous and lane-less traffic, is a challenging task. Traditionally density, defined as the number of vehicles in a road stretch, is used to quantify congestion. However, direct measurement of density is difficult and hence is usually estimated from other variables. In this pap...

Additional powertrain components and regenerative braking are two important factors that may affect the performance and stability of electrified vehicle cornering. The location of additional components affects the vehicle’s center of gravity (CG) position and thereby the stability of the vehicle. As regenerative braking is possible only on driven w...

This work provides a model-based approach to develop a wheel slip regulation scheme for Antilock Braking System (ABS) in Heavy Commercial Road Vehicles (HCRVs). Physical constraints of the actuator in the pneumatic brake system such as operating bandwidth and delay were considered in the design. The slip regulation scheme was designed using Power R...

Wheel lock is an undesired phenomenon in Heavy Commercial Road Vehicles (HCRVs) and wheel slip control within a desired range is of crucial importance for stable and effective braking. This study proposes a framework to distribute brake force dynamically between the front and rear wheels, primarily to avoid instability by preventing wheel lock. Fur...

Wheel Slip Regulation (WSR) is one of the Active Vehicle Safety Systems (AVSSs) for maintaining vehicle stability and maneuverability during emergency braking An approach for wheel slip prediction is proposed in this paper, which involves Auto-Regressive (AR) Time-Series modelling of longitudinal vehicle acceleration. This technique allows the usag...

This paper presents a dynamic brake force distribution (BFD) control strategy that allocates the brake force to each wheel based on the normal loads and coefficients of friction for a two-axle heavy commercial road vehicle (HCRV) for straightline braking. A three degree of freedom half car pitch model was used to calculate the dynamic load transfer...

Advanced Driver Assistance Systems in heavy commercial road vehicles (HCRVs) have become necessary with the increasing contribution of HCRVs to road accident fatalities, where human factors form the major contributor. Collision avoidance systems can help in reducing fatalities through automated braking when required. This study focused on the devel...

The focus of this paper is on the development of a vehicle-tracking algorithm using a solid-state LIDAR sensor for application to Collision Avoidance Systems (CAS) for Heavy Commercial Road Vehicles. Solid State LIDARs are relatively inexpensive compared to RADARs and point cloud LIDARs, and hence could accelerate commercialization of Advanced Driv...

For a realistic estimation of stresses and strains in the pavement, it is necessary to consider the dynamic normal load transferred from a truck to the pavement. The roughness of the pavement, and driving maneuver influences the dynamic load transferred. This study investigates the role of acceleration for a given pavement roughness profile. The re...

In this paper, a model based estimation scheme has been proposed to estimate density incorporating the heterogeneity and lane indiscipline observed in Indian traffic. In order to incorporate lane indiscipline, the road stretch under study was considered as multiple parallel strips. Time occupancy and composition based weighted vehicle length were u...

This work proposes a method to simulate wheel lock of a Heavy Commercial Road Vehicle (HCRV) using pneumatic brake circuit on a brake dynamometer. The proposed methodology lumps the effects of wheel slip and load transfer during straight-line braking into ‘equivalent inertia’ on the wheels. This inertia profile could then be imported on a dynamomet...

This paper deals with tracking of desired yaw rate generated by the path planner of an Autonomous Ground Vehicle (AGV) in the presence of unmodeled dynamics, changes in operating conditions and parametric uncertainties. A mathematical model considering the dynamics of the test vehicle and the steering actuator was used for controller design. The es...

In heavy commercial road vehicles, the air brake system is a critical vehicle safety system whose performance degradation increases the risk of accidents and hence requires periodic inspection and maintenance. The wear of brake pad lining and brake drum during operation leads to increase in the stroke of a component called pushrod whose ‘out-of-adj...

The phenomenon of platoon dispersion deals with the spreading out of groups of vehicles discharged together from a signal (platoon) as they move along the roadway during normal traffic operations. Understanding and analyzing this behavior is important in efficient traffic operations and management. There are different platoon dispersion models repo...

Hybrid electric vehicles are emerging technologies that are considered as eco-friendly alternative solutions to internal combustion engine–driven vehicles. This paper proposes a modified hybrid electric vehicle powertrain system that addresses the shortcomings of a series hybrid electric vehicle powertrain. The proposed configuration replaces the c...

An agricultural tractor finds extensive application in agriculture and is used with various types of implements. When it is driven with an implement attached to its rear, on-road or on uneven terrain, it experiences excessive vibrations in the pitch plane, which results in front wheel lift-off as an extreme scenario. The objective of this paper is...

Hybrid electric vehicles are considered as an eco-friendly alternative solution to conventional internal combustion engine driven vehicles. This paper investigates the development of a Series-Parallel hybrid electric vehicle powertrain for a heavy-duty truck based on vehicle performance requirements, and compares its performance with a Series hybri...

With increasing focus on addressing fossil fuel shortage and harmful automotive emissions, there has been a growing interest in hybrid electric and pure electric vehicles. A hybrid electric vehicle is driven by a combination of an internal combustion engine and an electric motor. The changes in the powertrain components result in changes in vehicle...

In electric and hybrid vehicles, regenerative braking is applied only at the driven wheels by the electric drive, whereas the non-driven wheels are not subjected to brake force during the pure regenerative braking mode. The application of pure regenerative brake may affect the vehicle’s lateral stability during a turn. The impact could be more seve...

A rear-end collision avoidance system (RECAS) could reduce accidents by assisting drivers during emergencies through autonomous braking. If the decision to intervene is made too early, the intervention can become a disturbance to the driver and if the decision is made too late, the safety benefits of the system will be reduced. Hence, proper threat...

Providing accurate information about bus arrival time to passengers can make public transport system more attractive. Such information helps the passengers by reducing the uncertainty on waiting time and the associated frustrations. However, accurate estimation of bus travel time is still a challenging problem, especially under heterogeneous and la...

Accurate travel time information of public transport will help operators to effectively manage and implement their operating strategies and help passengers by reducing the uncertainty about arrival time of buses at bus stops. The reliability of such information provided to passengers greatly depends on the prediction technique used, which in turn,...

The accuracy of travel time information given to passengers plays a key role in the success of any Advanced Public Transportation Systems (APTS) application. In order to improve the accuracy of such applications, one should carefully develop a prediction method. A majority of the available prediction methods considered the variation in travel time...