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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 slip variance regulation as a potential approach towards reference wheel slip estimation for wheel slip regulation (WSR). The variance regulation approach computes reference wheel slip using past wheel slip estimates and regulates wheel slip variation at a set point. This variance regulation problem was solved using least-squares estimation, yielding reference slip dynamics. A 3-staged nested control architecture was developed with reference slip dynamics to yield an anti-lock braking system (ABS) algorithm consisting of a brake controller, WSR algorithm and reference slip estimation. The algorithm was experimentally corroborated in a Hardware-in-Loop setup consisting of the pneumatic brake system of a heavy commercial road vehicle, and IPG TruckMaker®, a vehicle dynamics simulation software. The proposed ABS algorithm was tested on straight roads with homogeneous surfaces, split friction surfaces, and transition friction surfaces. It ensured stable braking in all road cases, with a 7%–18% reduction in braking distance on homogeneous road surfaces compared to the same vehicle without ABS. The vehicle directional stability was retained on a split-friction surface, and the ABS algorithm was observed to adapt to sudden transitions in the road surface.

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 ar...

Wheel lock in a vehicle during braking is detrimental to its safety, in addition to causing poor braking performance. Wheel slip regulation algorithms could potentially prevent wheel lock and are hence required to be tested and tuned thoroughly prior to in-vehicle deployment. Generally, software-in-the-loop and hardware-in-the-loop tests are explored before on-road vehicle testing. A brake dynamometer can potentially be utilized for wheel slip regulation testing, and this can be placed in between hardware-in-the-loop tests and on-road vehicle testing. Prior to evaluation of wheel slip regulation on a brake dynamometer, it is imperative to realize a wheel lock scenario. 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 captured through extensive tests on a hardware-in-the-loop platform that consists of a pneumatic brake setup interfaced with IPG TruckMaker® co-simulated with MATLAB/Simulink®, across varying load, road and braking conditions. Equivalent inertia profiles thus generated were then realized in the brake dynamometer, via mechanical discs and electrical inertia. Angular speed profiles from hardware-in-the-loop and dynamometer tests were compared to corroborate the framework. A close correlation between the profiles, highlighted by the root mean square deviation of the order of 100 rad/s, established the effectiveness of the proposed scheme.

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 instability may also lead to vehicle roll-over. ABS algorithms are broadly classified as Model-Based Algorithms (MBAs) and Rule-Based Algorithms (RBAs). MBAs are typically physics based and employ vehicle dynamic models. RBAs, which are currently predominantly used in vehicles, are threshold based. RBAs require measurement of wheel speed that is readily available, while MBAs require real time information on vehicle parameters and tire models. Most commercially available RBAs are proprietary and the details are not revealed. This has motivated the present study, and the physical significance of the wheel slip and wheel acceleration thresholds used in RBAs are clearly identified, backed by experiments from a Hardware-in-Loop (HiL) pneumatic brake setup along with IPG TruckMaker®, a software for vehicle dynamic simulation. This study is an important first step in developing an advanced RBA for HCRVs.

Perception of kinesthetic and tactile sensations forms the fabric of obtaining haptic feedback from remote or virtual environments through the interface that can be either tele-operated or virtual reality systems. A belt-type haptic device is a new fangled means to perceive these sensations along with directional information. Varying the speed and vibration levels of the belt can render appropriate tactile and kinesthetic feedback to the user through skin deformation. In this paper, a novel means for accurate measurement of both speed and vibration of the belt are presented in order to enhance the fidelity of the texture and force sensations. Information from multiple proximity sensors and piezoelectric vibration sensor is fused using state estimation techniques to get accurate measurements. These measurements, in turn, enhance the control quality of the belt speed and oscillation, hence enabling the user to experience the environment transparently. Furthermore, a graphical user interface (GUI) is developed in MATLAB to make the measurements accessible from a remote location through an IOT module, so that the parameters can be controlled as and when the haptic feedback needs to be improved.

Model Predictive Control (MPC) has been used in the automotive domain to control powertrain, suspension, and brakes. Active Vehicle Safety Systems (AVSSs), where the brake system plays a significant role, have gained much impetus since they can potentially reduce road fatalities. Wheel Slip Regulation (WSR) is a popular methodology used in developing AVSSs such as Antilock Brake System and Direct Yaw Control using brake control. This work proposes an MPC based algorithm for WSR utilizing linear longitudinal vehicle and wheel dynamics. The MPC problem is developed as a convex optimization formulation, ensuring that the control problem has a unique solution. The problem is formulated as a Quadratic Program with linear inequality constraints, and an efficient custom MPC solver is developed. The custom MPC solver reduces the number of computations by classifying the matrix operations into three categories, namely, constant matrices, reference-dependent matrices, and feedback-dependent matrices. The proposed MPC is evaluated using IPG TruckMaker®, a vehicle dynamics simulation software, interfaced with MATLAB Simulink®. The braking distance improvement with MPC is in the range of 10% to 40%, and the custom solver decreases the computational time of one iteration by 20 times compared to CVX, a MATLAB tool for convex programming.

Wheel slip regulation algorithms constitute a significant part of active vehicle safety systems in heavy commercial road vehicles. Any wheel slip regulation algorithm designed for set-point tracking requires a reference operating wheel slip irrespective of its control strategy. This reference slip is unique to each tire-road interface and changes with tire normal load. The present work proposes the optimal reference slip as one that minimizes braking distance, and introduces a recursive algorithm for its estimation. It further proposes a framework for reference slip estimation and wheel slip control. The credibility of the framework was established by testing in a Hardware-in-Loop setup consisting of a pneumatic braking system and IPG TruckMaker ® , a high fidelity vehicle dynamics simulation environment. The algorithm estimated the reference slip corresponding to different tire-road interfaces and resulted in stable braking maneuvers with 7-17% reduction in braking distance.

Wheel slip regulation (WSR) is an approach to achieve anti-lock braking, where the parameter, wheel slip ratio, is made to operate around a reference value. WSR algorithms can be rule-based or model-based. Model-based solutions require real-time information on vehicle parameters including tire model parameters that increases the challenge in their real-world implementation. Hence, this work proposes a novel triphase rule-based WSR algorithm for Heavy Commercial Road Vehicles, that employ an electro-pneumatic brake system. Since the direct measurement of wheel slip is not feasible, estimates from an Extended Kalman Filter are used to monitor and regulate slip. A real-time reference adaptation scheme is proposed to detect low friction road surfaces. The proposed algorithm is evaluated in a Hardware-in-Loop experimental setup, and shown to adapt to the road surface, prevent wheel lock, and reduce braking distance up to 19 % compared to the case without control.

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. Further, it ensures the maximum utilization of the available traction force at the tire-road interface that varies during the course of braking due to factors like load transfer. Wheel slip regulation provides an approach to maximize braking performance that subsumes the effects of varying road, load and braking conditions that occur during vehicle deceleration. The methodology proposed consists of a wheel slip controller that calculates the required brake force distribution parameters, which are then provided to the brake controller for control action. Sliding mode control was used because of the nonlinear nature of the longitudinal vehicle dynamic model considered and for robustness towards different parameter variations. The algorithm was implemented on a Hardware-in-Loop test setup consisting of a pneumatic air brake system, interfaced with IPG-TruckMaker® (a vehicle dynamic simulation software), and co-simulated with MATLAB-Simulink®. It was found that this algorithm improved the braking performance of a HCRV both in terms of stopping distance and vehicle stability.

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 usage of linear longitudinal vehicle dynamics for wheel slip estimation. A wheel slip prediction model was developed considering measurements from accelerometer and wheel speed sensor. This modified the Model Predictive Control (MPC) formulation to a univariate control input problem, involving braking torque. The objective function was devised for solving a least-squares reference tracking problem. An analytical solution for the MPC optimization problem was derived and implemented towards WSR. The proposed framework was programmed in MATLAB Simulink® and co-simulated with IPG TruckMaker® (a vehicle dynamic simulation software). The algorithm was tested in a Hardware-in-Loop (HiL) setup consisting of a pneumatic air brake system interfaced with IPG TruckMaker®. Open loop studies from HiL led to the inclusion of Kalman filter for estimate tuning and PID inner loop control for brake pressure transients, which improved wheel slip regulation.

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 dynamometer interface and realized using suitable inertia discs and an electric motor. Equivalent inertia was computed from test datasets obtained from a Hardware-in-Loop (HiL) experimental system consisting of an air brake system and IPG TruckMaker®, a vehicle dynamic simulation software. These datasets were obtained for various road, vehicle load and braking conditions. This framework would facilitate the evaluation of wheel slip regulation algorithms using a brake dynamometer by capturing necessary dynamics of HCRVs during braking. It is expected that such testing can be placed between HiL and on-road tests, and would provide greater confidence in Active Safety Systems (ASSs) before their deployment on vehicles.

Smart materials; for example shape memory alloy (SMA) is used as actuator because of change in its properties like shape; dimension; stiffness; impedance; strain; natural frequency; with an external stimulus. Moreover; using SMA material in actuators makes the design simple and compact; at the same time providing large strain. These fundamental characteristics make them increasingly essential for different real time systems. This paper presents the design and implementation of a piston type actuator using the stiffness principle of shape memory alloy wire to provide a linear motion. A preliminary study is performed to investigate on the factors that influence the stiffness of the SMA wire piston type actuator for a translational movement of the actuator by design. The characteristics reveal that the stiffness is correlated with and influenced by the performance indices like the frequency of operation; displacement effected and force generated.

The widespread use of airborne vehicles and its growing applications in various domains can be attributed to their ability to operate in inaccessible areas, thus decreasing the human loss in major accidents, and making access easy to dangerous conditions. These pilotless airborne vehicles with some remote sensing techniques involved in it, are emerging as a new technology. The airborne vehicles are enduring, cost effective and also provide a reliable platform for surveying. Consequently, small airborne vehicles, here Quad copter, equipped with sophisticated components can capture and transmit the image or video to the Data Base. They are sent for processing and made accessible to the Geographical Information System (GIS), where further analysis is done for the proceedings of the rescue operation. This application finds a great utility predominantly in industries and military.