Automotive engineering powertrain, chassis system and vehicle body – part 2
➤ Gửi thông báo lỗi ⚠️ Báo cáo tài liệu vi phạmNội dung chi tiết: Automotive engineering powertrain, chassis system and vehicle body – part 2
Automotive engineering powertrain, chassis system and vehicle body – part 2
SWeltB I rmiWBKWNMiB I iTTi GTTiWSiSfiiWlB IĨTĨĨ ƠĨ-1 iWCTCiHI iTTi GWiSectionThirteenVehicle control systemsKHOTHUVIEN.COM391Chapter 13.1Vehicle moti Automotive engineering powertrain, chassis system and vehicle body – part 2 ion controlWilliam Ribbons13.1.1 Introduction13.1.2 Typical cruise control systemThe term vehicle motion refers to its translation along and rotation about all three axes (Ỉ.C., longitudinal, lateral, and vertical). By the term longitudinal axis, wc mean the axis that is parallel to the ground (vehi Automotive engineering powertrain, chassis system and vehicle body – part 2 cle al rest) along the length of the car. The lateral axis is orthogonal to the longitudinal axis and is also parallel to the ground (vehicle al rest)Automotive engineering powertrain, chassis system and vehicle body – part 2
. The vertical axis is orthogonal to both the longitudinal and lateral axes.Rotations of the vehicle around these three axes correspond to angular disSWeltB I rmiWBKWNMiB I iTTi GTTiWSiSfiiWlB IĨTĨĨ ƠĨ-1 iWCTCiHI iTTi GWiSectionThirteenVehicle control systemsKHOTHUVIEN.COM391Chapter 13.1Vehicle moti Automotive engineering powertrain, chassis system and vehicle body – part 2 t about the vertical axis; and pilch refers to angular displacement about the lateral axis.Electronic controls have been recently developed with the capability to regulate the motion along and about all three axes. Individual car models employ various selected combinations of these controls. This ch Automotive engineering powertrain, chassis system and vehicle body – part 2 apter discusses motion control electronics beginning with control of motion along the longitudinal axis in the form of a cruise control system.The forAutomotive engineering powertrain, chassis system and vehicle body – part 2
ces that influence vehicle motion along the longitudinal axis include the powertrain (including, in selected models, traction control), the brakes, thSWeltB I rmiWBKWNMiB I iTTi GTTiWSiSfiiWlB IĨTĨĨ ƠĨ-1 iWCTCiHI iTTi GWiSectionThirteenVehicle control systemsKHOTHUVIEN.COM391Chapter 13.1Vehicle moti Automotive engineering powertrain, chassis system and vehicle body – part 2 rade). In a traditional cruise control system, the tractive force due to the powertrain is balanced against the total drag forces to maintain a constant speed. In an ACC system, brakes arc also automatically applied as required to maintain speed when going down a hill of sufficiently steep grade.Aut Automotive engineering powertrain, chassis system and vehicle body – part 2 omotive cruise control is an excellent example of the type of electronic feedback control system. Recall that the components of a control system incluAutomotive engineering powertrain, chassis system and vehicle body – part 2
de the plant, or system being controlled, and a sensor for measuring the plant variable being regulated. It also includes an electronic control systemSWeltB I rmiWBKWNMiB I iTTi GTTiWSiSfiiWlB IĨTĨĨ ƠĨ-1 iWCTCiHI iTTi GWiSectionThirteenVehicle control systemsKHOTHUVIEN.COM391Chapter 13.1Vehicle moti Automotive engineering powertrain, chassis system and vehicle body – part 2 system generates an error signal constituting the difference between the desired and actual values of this variable. It then generates an output from this error signal that drives an electromechanical actuator. The actuator controls the input to the plant in such a way that the regulated plant varia Automotive engineering powertrain, chassis system and vehicle body – part 2 ble is moved toward the desired value.In the case of a cruise control, the variable being regulated is the vehicle speed. The driver manually sets theAutomotive engineering powertrain, chassis system and vehicle body – part 2
car speed at the desired value via the accelerator pedal. Upon reaching the desired speed the driver activates a momentary contact switch that sets tSWeltB I rmiWBKWNMiB I iTTi GTTiWSiSfiiWlB IĨTĨĨ ƠĨ-1 iWCTCiHI iTTi GWiSectionThirteenVehicle control systemsKHOTHUVIEN.COM391Chapter 13.1Vehicle moti Automotive engineering powertrain, chassis system and vehicle body – part 2 ting the throttle via a throttle actuator.Under normal driving circumstances, the total drag forces acting on the vehicle are such that a net positive traction force (from the powertrain) is required to maintain a constant vehicle speed. I lowcvcr, when the car is on a downward sloping road of suffi Automotive engineering powertrain, chassis system and vehicle body – part 2 cient grade, constant vehicle speed requires a negative tractive force that the powertrain cannot deliver. In this case, the car will accelerate unlesAutomotive engineering powertrain, chassis system and vehicle body – part 2
s brakes are applied. For our initialUndentatuiinc Automotiiv Electronics; ISBN: 9780750675994Copyright © 2ÍXI3 Elsevier Ltd; All rights of reproductiSWeltB I rmiWBKWNMiB I iTTi GTTiWSiSfiiWlB IĨTĨĨ ƠĨ-1 iWCTCiHI iTTi GWiSectionThirteenVehicle control systemsKHOTHUVIEN.COM391Chapter 13.1Vehicle moti Automotive engineering powertrain, chassis system and vehicle body – part 2 ot occur and that no braking is required.'rhe plant being controlled consists of the powertrain (Ĩ.C., engine and drivetrain), which drives the vehicle through the drive axles and wheels. As described above, the load on this plant includes friction and aerodynamic drag as well as a portion of the ve Automotive engineering powertrain, chassis system and vehicle body – part 2 hicle weight when the car is going up and down hills.The configuration for a typical automotive cmisc control is shown in Fig. 13.1-1. The momentary cAutomotive engineering powertrain, chassis system and vehicle body – part 2
ontact (pushbutton) switch that sets the command speed is denoted S| in Fig. 13.1-1. Also shown in this figure is a disable switch that completely disSWeltB I rmiWBKWNMiB I iTTi GTTiWSiSfiiWlB IĨTĨĨ ƠĨ-1 iWCTCiHI iTTi GWiSectionThirteenVehicle control systemsKHOTHUVIEN.COM391Chapter 13.1Vehicle moti Automotive engineering powertrain, chassis system and vehicle body – part 2 Fig. 13.1-1 and is a safety feature. In an actual cruise control system the disable function can be activated in a variety of ways, including the master power switch for the cruise control system, and a brakepedal-activated switch that disables the cruise control any time that the brake pedal is mo Automotive engineering powertrain, chassis system and vehicle body – part 2 ved from its rest position. The throttle actuator opens and closes the throttle in response to the error between the desired and actual speed. WheneveAutomotive engineering powertrain, chassis system and vehicle body – part 2
r the actual speed is less than the desired speed the throttle opening is increased by the actuator, which increases vehicle speed until the error is SWeltB I rmiWBKWNMiB I iTTi GTTiWSiSfiiWlB IĨTĨĨ ƠĨ-1 iWCTCiHI iTTi GWiSectionThirteenVehicle control systemsKHOTHUVIEN.COM391Chapter 13.1Vehicle moti Automotive engineering powertrain, chassis system and vehicle body – part 2 a cruise control system is shown in Fig. 13.1-2. In the cruise control depicted in this figure, a proportional integral (Pl) control strategy has been assumed. 1 lowcvcr, there arc many cruise control systems still on the road today with proportional (P) controllers. Nevertheless, the PI controller Automotive engineering powertrain, chassis system and vehicle body – part 2 is representative of good design for such a control system since it can reduce speed errors due to disturbances (such as hills) to zero. In this straAutomotive engineering powertrain, chassis system and vehicle body – part 2
tegy an error e is formed byFig. 13.1-2 Ouse control block diagram.394Vehicle motion controlsubtracting (electronically) the actual speed va from the SWeltB I rmiWBKWNMiB I iTTi GTTiWSiSfiiWlB IĨTĨĨ ƠĨ-1 iWCTCiHI iTTi GWiSectionThirteenVehicle control systemsKHOTHUVIEN.COM391Chapter 13.1Vehicle moti Automotive engineering powertrain, chassis system and vehicle body – part 2 roportional to the integral of the error:K/jeASWeltB I rmiWBKWNMiB I iTTi GTTiWSiSfiiWlB IĨTĨĨ ƠĨ-1 iWCTCiHI iTTi GWiSectionThirteenVehicle control systemsKHOTHUVIEN.COM391Chapter 13.1Vehicle motiGọi ngay
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