Showing papers on "Dynamic braking published in 2000"

Device for controlling spin/driftout of vehicle compatibly with roll control

Abstract: A moving behavior control device for a vehicle calculates first target braking forces to be applied to the respective wheels for stabilizing the vehicle against a turn instability, second target braking forces to be applied to the respective wheels for stabilizing the vehicle against a roll instability, and target overall braking forces to be applied to the respective wheels by integrating the first and second target braking forces, and applies braking forces to the respective wheels according to the target overall braking forces, wherein the applied braking forces are decreased according to a first rate schedule by which the applied braking forces are decreased at a first rate according to an excess of the applied braking forces relative to the target overall braking forces when the vehicle is running at no probability of rolling beyond a predetermined threshold roll, and according to a second rate schedule by which the braking forces are lowered at a second rate smaller than the first rate according to the excess when the vehicle is running at such a probability.

System and method for braking an electric drive vehicle on a low Mu surface

Abstract: Strategies other than immediate elimination of regenerative braking (FIG. 2) are invoked when an incipient wheel lock-up is detected, the ABS becomes active, and/or incipient wheel slip is detected. The strategies include: reducing the regenerative braking torque as a function of the coefficient of friction of a surface on which the vehicle is traveling (FIG. 3); and adjusting regenerative braking in relation to the rate at which wheel slip is changing (FIG. 4). Some of the strategies may be applied on an individual wheel basis (FIG. 5), and some of the strategies may be applied in conjunction with operating friction brakes of the vehicle to apply at least some of the reduction in regenerative braking torque as friction brake torque (FIG. 1).

Train handling techniques and analysis

Abstract: This is a method of analyzing train handling by setting a standard for the run, collecting train operating or handling data from the run and determining operating constraints during the run which are not included in the standard run. The determination of operating constraints during a run also includes determining differences between the operating constraints during the run of those included in the standard. The train handling data is compared to the standard and the comparison is adjusted for the operating constraints. The adjustment of the comparison includes nullifying any deviation of the handling data from the standard resulting from the operating constraints. A report is created from the standard and the handling data correlating the energy usage for specific categories. These categories include one or more of pneumatic braking, dynamic braking and track topology. The report further includes energy adjustments for the operating constraints determined during the run.

Dynamic brake circuit and semiconductor inverter using dynamic brake circuit

Abstract: The invention prevents a voltage change dv/dt of an inverter from directly causing an erroneous firing of a semiconductor brake switch, which may short-circuit the inverter during operation. To brake a motor (10) driven by an inverter which consists of a three-phase AC power supply (1), a three-phase bridge rectifier (3), a smoothing capacitor (6) and a semiconductor switching element (7), a dynamic braking circuit turns on a semiconductor braking switch (14) to short-circuit feeder lines (11) for the motor (10) so that a braking resistor (15) may absorb energy. A large resistor (20) is connected between the positive side of the smoothing capacitor (6) and the positive side of the semiconductor braking switch (14), and a snubber capacitor (17) of a snubber circuit (18) connected in parallel with the semiconductor braking switch (14) is charged through the resistor (20) before the inverter is started.

Modeling Combined Braking and Steering Tire Forces

Abstract: The force distributed over the contact patch between a tire and a road surface is typically modeled in component form for dynamic simulations. The two components in the plane of the contact patch are the braking, or traction force, and the steering, or side or cornering force. A third force distributed over the contacts patch is the normal force, perpendicular to the road surface. The two tangential components in the plane of the road are usually modeled separately since they depend primarily on independent parameters, wheel slip and sideslip. Mathematical expressions found in the literature for each component include exponential functions, piecewise linear functions and the Bakker-Nyborg-Pacejka equations, among others. Because braking and steering frequently occur simultaneously and their resultant tangential force is limited by friction, the two components must be properly combined for a full range of the wheel slip and sideslip parameters. This paper examines the way in which these two components are combined for an existing approach known as the Nicolas-Comstock model. First, performance criteria for tire modeling are proposed. Then the Nicolas-Comstock model is examined relative to the criteria. As originally proposed, this model falls short of meeting the criteria over the full range of transverse and longitudinal wheel slip values and sideslip angles. A modified version of the Nicolas-Comstock model is presented that satisfies these performance criteria. Finally, comparisons are made of the Modified Nicolas-Comstock model to other combined tire force models and to existing tire force measurements.

Adaptive emergency braking control using a dynamic tire/road friction model

Abstract: A controller for emergency braking of vehicles in automated highway systems (AHS) is designed. The scheme is based on the estimation of both the LuGre tire/road friction dynamic model and the braking system gain. The controller estimates the tire/road relative velocity which achieves maximum braking force based on a quasi-static solution of the LuGre friction model and sets the master cylinder pressure to track that relative velocity. This control system is designed to work in conjunction with antilock-braking-systems providing two advantages: less chattering during braking and a source of a priori information regarding safe spacing.

Setting braking pressure for vehicle involves releasing first braking pressure, applying second pressure for long-term parking, applying first pressure for start-up, removing to drive off

Abstract: The method involves maintaining the required braking pressure to ensure that a vehicle is not moved by an external force by determining the difference between a drive torque and an external moment on the vehicle and generating a first braking pressure by a first brake(3) so that a braking force is exerted on at least one vehicle wheel if the drive torque is less than the external moment. The first braking pressure is released and a second braking pressure simultaneously produced by a second brake(4) if a long-term parking condition is fulfilled. The second braking pressure is released and the first braking pressure is applied simultaneously if a start-up condition is fulfilled and the first braking pressure is released if a driving off condition is fulfilled.

Vehicle braking apparatus and vehicle braking method

Abstract: In attaining a target vehicle braking force corresponding to a pedal depression force, an assigned braking force is obtained by subtracting a minimum braking force of a hydraulic braking device corresponding to the pedal depression force from the target vehicle braking force. Then, a distributive braking force of the hydraulic braking device is obtained by subtracting an actual regenerative braking force from the assigned braking force. And, a boost ratio of the hydraulic braking device is controlled based on a target hydraulic braking force which is a sum of the minimum braking force and the distributive braking force. Thus, the braking force of the hydraulic braking device is always utilized for attaining the target vehicle braking force.

Dynamic braking method and apparatus

Abstract: An apparatus for decreasing speed of an inverter driven inertial load within a time period for use with a dynamic brake across a DC link including a controller for controlling the inverter to regulate the power returned to the brake such that, when a brake command is received, the power is increased during a power-up period while motor deceleration begins and up to a constant power level after which the constant power level is maintained by increasing torque such that the dynamic brake is fully used during the majority of a braking cycle and a method to accomplish the same.

Antilock brake system modelling and fuzzy control

Abstract: A vehicle braking model for straight line braking analysis is presented. This model includes the longitudinal vehicle dynamics, tyre dynamics, and road surface model. The developed model is tested on an asphalt surface on a step brake input. A fuzzy logic antilock brake system (ABS) controller is proposed to minimize the stopping distance under emergency braking conditions. The performance of the fuzzy logic controller with a manual brake system in an emergency braking manoeuvre is compared. (A)

Characteristics of the Aerodynamic Brake of the Vehicle on the Yamanashi Maglev Test Line

Abstract: The Yamanashi Maglev system has two types of main braking systems: regenerative braking system (primary brake using electrodynamic power) and on-board mechanical braking system (backup brake). The mechanical backup braking system is installed on vehicles. It is used to safely and accurately stop the vehicle in case the electrical braking system has failed. On the Yamanashi Maglev Test Line, an aerodynamic braking system is used as an element of the mechanical backup braking system. In the aerodynamic braking system, braking force is obtained by aerodynamic drag which is generated by unfolded brake panels. The aerodynamic brake is very effective in high speed operation, because the aerodynamic drag is proportional to the square of vehicle speed. This paper reports the aerodynamic brake system and results of running tests on the Yamanashi Maglev test line.

Compression braking control for heavy-duty vehicles

Abstract: Modern heavy-duty vehicles are equipped with a compression braking mechanism that augments their braking capability and reduces the wear of the conventional friction brakes. We consider a vehicle speed control problem using a continuously variable compression braking mechanism. The variability of the compression brake is achieved through the control of the brake valve of the vehicle's turbocharged diesel engine. An adaptive controller is designed to ensure good speed tracking performance in brake-by-wire, or vehicle-following, driving scenarios even during large variations in mass and road grade. Our approach is to first consider the model without compression brake actuator dynamics and derive a model reference adaptive controller using the speed-gradient procedure. Then, the actuator dynamics are included in the design via the use of the backstepping procedure. The backstepping controller is implemented with a simplified numerical differentiator-based approximation.

Optimum suspension design for motorcycle braking

Abstract: A mathematical model for the in-plane dynamic analysis of motorcycles is presented and the performance during an emergency braking manoeuvre is analysed. The effects of braking torque amplitude and time constant are discussed and the problems of lock-up and loss of contact of the rear wheel are highlighted. The suspensions' vibrations during braking are analysed by means of modal analysis. An optimisation method is developed in order to find the braking torque and the suspension parameters that minimise the stopping distance. The method takes the complete dynamic behaviour of the vehicle during braking into account and is based on a non-derivative minimisation algorithm. Several results are presented that show the possibility of shortening the stopping distance by optimum design of one or both of the suspensions.

System and method for regenerative and antiskid braking within an electric vehicle

Abstract: A braking system 12 for use with an electric vehicle 10 including an electric motor/generator assembly 14 , and a conventional electrical energy storage device 16 . Motor/generator 14 selectively drives wheels 20 of vehicle 12 . The braking system 12 includes a motor control module 26 which is communicatively coupled to motor/generator 14 and which selectively causes motor/generator 14 to provide a regenerative braking function at wheels 20 of vehicle 10 . Braking system 10 further includes an antiskid braking system which selectively provides friction braking at wheels 20 and 24 of vehicle 10 . The braking system 12 is effective to detect antiskid braking events at each of the wheels 20, 24 , to selectively provide an antiskid braking function at each of wheels 20, 24 where the antiskid braking events are detected, and to selectively disable the regenerative braking function only when an antiskid braking event is detected at either of wheels 20.

Temperature dependent regenerative brake system for electric vehicle

Abstract: A braking system for a motor vehicle having braking wheels 16, 18, a service brake pedal, a friction braking system operative upon the braking wheels 16, 18 in response to actuation of the vehicle brake pedal 26, an anti-lock braking system cooperative with the friction braking system to control the friction braking force applied to the braking wheels 16, 18 upon detection of slippage of the braking wheels 16, 18, a regenerative braking system operative upon the braking wheels 16, 18 in response to actuation of the vehicle brake pedal 26 for selectively generating an applied regenerative braking force through the braking wheels 16, 18, and an ambient temperature sensor 52. The regenerative braking system operates at a first effective rate of applied regenerative braking force upon application of the brake pedal 26 at an ambient temperature above a desired temperature, and the regenerative braking system operates at a second, lower effective rate of applied regenerative braking force at an ambient temperature below a desired temperature. Upon activation of the anti-lock braking system, the applied regenerative braking force is reduced at a first predetermined rate when the ambient temperature is above a desired temperature and the regenerative braking force is reduced at a second, faster predetermined rate when the ambient temperature is below a desired temperature.

Motor vehicle braking assistance method involves detecting whether vehicle is stationary and maintaining braking to keep vehicle stationary if partial or full release of brake actuator is detected

Abstract: The method involves detecting whether the vehicle is stationary and maintaining braking to keep the vehicle stationary if partial or full release of the brake actuator is detected. Braking can be maintained at least initially when the actuator is fully released when stationary, and braking can be partly or fully released when the driver initiates a driving-off process. An Independent claim is also included for an arrangement for assisting the braking of a motor vehicle

Method and device for controlling a braking system

Abstract: Proposed are a method and a device for controlling a braking system of a vehicle, braking force being maintained in at least one operating state at least one wheel of the vehicle while the braking pedal is actuated, independently of the degree of the pedal actuation. In this context, different conditions are provided jointly or alternatively for activating or deactivating the function.

Braking torque control apparatus and method

Abstract: A pair of shoes are expanded by driving an electric brake motor. Due to the friction engagement of the shoes with a drum inner peripheral surface, a braking force is applied to a wheel. An actual braking torque is detected by a strain sensor that detects the load applied to an anchor pin. Through a feedback control using the actual braking torque, the electric motor is driven and controlled so that the actual braking torque becomes equal to a target braking torque that is determined in accordance with the amount of operation of a brake pedal. When the actual braking torque is undetectable, for example, during a stop of a vehicle, the electric motor is driven and controlled through an actuating force control using the current through the electric motor that is detected by a motor current sensor. The braking torque control apparatus controls the actual braking torque to a magnitude corresponding to brake operation, regardless of the magnitude of the coefficient of friction between a friction engagement member and brake rotor. Even when the braking torque is undetectable, the apparatus executes brake control in a good manner.

Apparatus and method for determining direction of locomotive travel during dynamic braking

Abstract: An apparatus for determining the direction of locomotive travel while in dynamic braking is disclosed. This direction of travel is derived from current sensors associated with the locomotive traction motors. When in the dynamic braking mode, current flows through the current sensors in a first direction when a train is traveling in the first direction and reverses the direction of flow when the train is traveling in a second direction.

Improved back-up braking in vehicle braking systems

Abstract: A vehicle braking system comprising an electro-hydraulic braking means of the type which operates normally in a brake-by-wire mode wherein hydraulic pressure is applied to braking devices at the vehicle wheels (18a-d) in proportion to the driver's braking demand as sensed electronically at a brake pedal (10), and which, if the brake-by-wire mode should fail, operates in a push-through mode wherein hydraulic pressure is applied to the braking devices at the vehicle wheels (18) by way of a master cylinder (34) coupled mechanically to the brake pedal (10), and an electric parking braking means for enabling the braking devices to be actuated for parking braking purposes. For supplementing the push-through braking provided by the electro-hydraulic braking means in the event that the brake-by-wire mode has failed, it is arranged that the operation of the foot pedal (10) by the driver also causes operation of the electric parking braking.

Methods for improving braking performance in electronically-controlled hydraulic brake systems

Abstract: An electronically controlled vehicular hydraulic brake system provides anti-lock braking, traction control, and vehicle stability control. The system includes a hydraulic control unit (HCU) containing control valves and other components in fluid communication with wheel brakes. Low temperatures cause the viscosity of hydraulic fluid to increase. Performance of the braking system can be improved at low temperatures according to methods of this invention. A first preferred method of improving braking performance is to increase the brake fluid temperature inside the HCU. Several examples of methods to increase fluid temperature inside the HCU are presented. A second preferred method of improving braking performance is to preload the wheel brakes with a pressure that does not adversely affect normal driving. Several examples of methods to preload the wheel brakes are presented.

Application of pure electric braking system to electric railcars

Abstract: A "pure electric braking system" is able to brake a railcar to standstill without friction braking by utilizing only the electric brakes. Our research group is realizing the benefits and investigating the possibility of an ideal braking system for electric railcars. This paper describes the principal system of pure electric braking tested on actual cars, test results collected from running the test, and long term revenue service and their evaluations. A series of test and revenue services have proven the system to have excellent high stability and high performance. This method of braking offers an efficient and low cost alternative aid to the modern day train braking system.

Braking torque control apparatus

Abstract: A pair of shoes are expanded by driving an electric brake motor (30). Due to the friction engagement of the shoes with a drum inner peripheral surface, a braking force is applied to a wheel. An actual braking torque is detected by a strain sensor (314) that detects the load applied to an anchor pin. Through a feedback control using the actual braking torque, the electric motor (30) is driven and controlled so that the actual braking torque becomes equal to a target braking torque that is determined in accordance with the amount of operation of a brake pedal (40). When the actual braking torque is undetectable, for example, during a stop of a vehicle, the electric motor (30) is driven and controlled through an actuating force control using the current through the electric motor (30) that is detected by a motor current sensor (31). The braking torque control apparatus controls the actual braking torque to a magnitude corresponding to brake operation, regardless of the magnitude of the coefficient of friction between a friction engagement member and a brake rotor. Even when the braking torque is undetectable, the apparatus executes brake control in a good manner.

Motor vehicle, e.g. tractor, with control system that provides selective wheel braking for assisting vehicle steering

Abstract: The automobile (1) has an IC engine (7), coupled via a switched transmission (8), a clutch (9,12) and a drive differential (10) to the driven wheels, a braking system allowing independent braking of the driven wheels, a steering system (24) operated via a steering wheel (25) and a control system (23) providing selective braking of the wheel on the inside of the curve, for assisting steering at low velocities above a given steering angle. The control system monitors the state of the switched transmission and the clutch for providing the selective braking for assisting the steering, with both the clutch and the switched transmission controlled by the control system during the braking assisted steering.

Method and apparatus for warning a following vehicle during braking

Abstract: A method and apparatus for warning a following vehicle when a vehicle in front applies its brakes are provided. At least one brake light of a vehicle illuminates during a braking process as the braking value increases in conformity with a present value of the braking value. After the value drops below the maximum value, the illumination continues for a retention time that is a function of the braking process, and after the conclusion of the retention time fades during a period of time that is a function of the braking process.