The present disclosure relates to determination of roll angle and bank angle for a device using suspension displacement data. While the roll angle and the bank angle for a vehicle on a banked road may be estimated using a roll rate sensor and lateral accelerometer, a vehicle may not always be equipped with such sensors.
Disclosed herein is a device having a body operatively connected to a plurality of wheels, with the plurality of wheels being positioned on a banked surface defining a bank angle (β) (relative to an environmental frame horizontal or absolute horizontal). A suspension system is operatively connected to the plurality of wheels and includes at least one suspension sensor configured to provide suspension displacement data. A controller is in communication with the suspension sensor and has a processor and tangible, non-transitory memory on which is recorded instructions. Execution of the instructions by the processor causes the controller to obtain the suspension displacement data from the suspension sensor. The controller is configured to determine a plurality of predetermined parameters, a yaw rate (r) and a longitudinal velocity (Vx) of the device. The plurality of predetermined parameters includes a first factor (A) and a second factor (B). A roll angle (φ) is determined based at least partially on the suspension displacement data. The controller is configured to determine the bank angle (β) based at least partially on the roll angle (φ), a yaw rate (r), a longitudinal velocity (Vx) and the plurality of predetermined parameters. Operation of the device is controlled based partly on at least one of the roll angle (φ) and the bank angle (β).
The first factor (A) may be based at least partially on a selected bank angle (βs) and a selected roll angle (φs) corresponding to the selected bank angle (βs) such that
The selected bank angle (βs) is between 0 and 15 degrees, inclusive. The second factor (B) may be based at least partially on the first factor (A) and a gravitational constant (g) such that
Here r0, φ0 and Vx0 are the yaw rate, roll angle and longitudinal velocity, respectively, when the bank angle (β) is zero degrees.
The plurality of wheels includes a first wheel and a second wheel, with the device including a first axle operatively connecting the first wheel and the second wheel. The plurality of predetermined parameters includes a third factor (C), based partly on the first axle. The suspension displacement data includes a first displacement (ΔZLF) between respective coordinates along a z axis of a first corner (z=Z1) of the body and a center (z=zu1) of the first wheel such that ΔZLF=−(Z1−zu1). The suspension displacement data includes a second displacement (ΔZRF) between respective coordinates along the z axis of a second corner (z=Z2) of the body and a center (z=zu2) of the second wheel such that ΔZRF=−(Z2−Zu2). The roll angle (φ) may be defined as
The plurality of wheels may include a third wheel and a fourth wheel, with the device including a second axle operatively connecting the third wheel and the fourth wheel. The plurality of predetermined parameters includes a fourth factor (D), based partly on the second axle. The suspension displacement data may include a third displacement (ΔZLR) between respective coordinates along the z axis of a third corner (z=Z3) of the body and a center (z=zu3) of the third wheel such that ΔZLR=−(Z3−zu3). The suspension displacement data may include a fourth displacement (ΔZRR) between respective coordinates along the z axis of a fourth corner (z=Z4) of the body and a center (z=zu4) of the fourth wheel such that ΔZRR=−(Z4−zu4). The roll angle (φ) may be defined as:
The plurality of predetermined parameters may include a yaw moment of inertia (Izz), a pitch moment of inertia (Iyy), a mass (M) of the device and a distance (Zc) between an overall center of gravity of the device and a center of gravity of a sprung portion of the device. The bank angle (β) is based on the roll angle (φ), the yaw rate (r), the longitudinal velocity (Vx), the plurality of predetermined parameters and a gravitational constant (g) such that:
Controlling operation of the device based partly on at least one of the roll angle (φ) and the bank angle (β) may include transmitting a message if at least one of the roll angle (φ) and the bank angle (β) is above a respective predefined threshold. Controlling operation of the device may include limiting a speed of the device if at least one of the roll angle (φ) and the bank angle (β) is above their respective predefined thresholds.
Also disclosed is a method of controlling operation of a device having a body operatively connected to a plurality of wheels, the plurality of wheels being positioned relative to a banked surface defining a bank angle (β), a suspension system operatively connected to the plurality of wheels and having at least one suspension sensor, and a controller in communication with the at least one suspension sensor. The method enables online estimation of the roll angle (φ) and the bank angle (β) without requiring the following: a roll rate sensor, a lateral accelerometer, an observer, a tire model, tire sensors or road information. The method enables reduced cost and reduced complexity.
The method includes obtaining suspension displacement data from the suspension sensor and obtaining a plurality of predetermined parameters, a yaw rate (r) and a longitudinal velocity (Vx). The plurality of predetermined parameters includes a first factor (A) and a second factor (B). The method includes determining a roll angle (φ) based at least partially on the suspension displacement data and determining the bank angle (β) based at least partially on the roll angle (φ), the yaw rate (r), the longitudinal velocity (Vx) and the plurality of predetermined parameters. Operation of the device is controlled based partly on at least one of the roll angle (φ) and the bank angle (β).
The above features and advantages and other features and advantages of the present disclosure are readily apparent from the following detailed description of the best modes for carrying out the disclosure when taken in connection with the accompanying drawings.
Referring to the drawings, wherein like reference numbers refer to like components,
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It is to be understood that the device 10 may employ any type of suspension and sensor technology available to those skilled in the art. For example, the suspension sensor 36 may include a strain gage configured to vary its electrical resistance with a variation of strain elements at the surface of installation. The strain elements may be defined as the relative displacement of a local segment of spring, shock absorber, or other component of the suspension mount. The resistance change of the strain gage may be measured using a Wheatstone bridge (not shown) or other unit. The suspension sensor 36 may be configured to convert the resistance change of the strain gage into electrical stimuli for transmission to a controller C.
Alternatively, the suspension sensor 36 may include a magnetorheological (MR) or carrier fluid which is filled with micrometer-sized magnetic particles. When subjected to a magnetic field, the magnetic particles increase the viscosity of the fluid, rendering it viscoelastic solid. The suspension sensor 36 may be configured to convert the change in physical properties of the magnetorheological fluid (MR) into electrical stimuli for transmission to a controller C.
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If the device 10 has more than two wheels, the suspension displacement data may further include a third displacement (ΔZLR) (left rear) and a fourth displacement (ΔZRR) (right rear). Referring to
In block 104 of
The plurality of predetermined parameters includes a first factor (A) and a second factor (B). The first factor (A) may be based at least partially on a selected bank angle (βs) and a selected roll angle (φs) corresponding to the selected bank angle (βs) such that
The selected bank angle (βs) is between 0 and 15 degrees, inclusive. The second factor (B) may be based at least partially on the first factor (A) and a gravitational constant (g) such that
Here r0, φ0 and Vx0 are the yaw rate 62, roll angle 48 and longitudinal velocity, respectively, when the bank angle (β) is zero degrees. The first factor (A) and the second factor (B) may be determined in a test cell or under laboratory conditions with the device 10.
The plurality of predetermined parameters may include a yaw moment of inertia (Izz), a pitch moment of inertia (Iyy), a (total) mass (M) of the device 10 and the distance 54 (Zc) between the overall center of gravity 52 of the device 10 and the sprung mass point 50 (center of gravity of the sprung portion of the device 10) (see
Referring to
In block 106 of
For a device 10 with at least two wheels, the roll angle 48 (φ) may be defined as
In block 108 of
Controlling operation of the device 10 based at least partially on at least one of the roll angle 48 (φ) and the bank angle 40 (β) may include: transmitting a message if at least one of the roll angle 48 (φ) and the bank angle 40 (β) is above a respective predefined threshold. The message may include, but is not limited to, a visual message displayed on an instrument panel 66 of the device 10, an audible chime or a haptic alert. If the device 10 is an autonomous vehicle, the message may be transmitted to a fleet operator. The respective predefined thresholds may be selected based on the particular device 10. In one example, the respective predefined thresholds are 5 degrees and 10 degrees, respectively, for the roll angle 48 (φ) and the bank angle 40 (β).
Controlling operation of the device 10 may include limiting the speed of the device 10 if at least one of the roll angle 48 (φ) and the bank angle 40 (β) is above their respective predefined thresholds. The roll angle 48 (φ) and the bank angle 40 (β) play significant roles in the dynamics of the device 10 and may be employed as inputs for various control algorithms, including adaptive cruise control modules and stability control modules, thereby improving the functioning of the device 10. Additionally, the roll angle 48 (φ) and the bank angle 40 (β) may be used in support of autonomous driving functions, particularly when the device 10 is turning and/or when the road surface is rapidly changing. The method 100 enables online estimation of the roll angle 48 (φ) and the bank angle 40 (β) without requiring the following: a roll rate sensor, a lateral accelerometer, an observer, a tire model, tire sensors or road information, thereby enabling reduced cost and reduced complexity.
The controller C of
Look-up tables, databases, data repositories or other data stores described herein may include various kinds of mechanisms for storing, accessing, and retrieving various kinds of data, including a hierarchical database, a set of files in a file system, an application database in a proprietary format, a relational database management system (RDBMS), etc. Each such data store may be included within a computing device employing a computer operating system such as one of those mentioned above, and may be accessed via a network in one or more of a variety of manners. A file system may be accessible from a computer operating system, and may include files stored in various formats. An RDBMS may employ the Structured Query Language (SQL) in addition to a language for creating, storing, editing, and executing stored procedures, such as the PL/SQL language mentioned above.
The detailed description and the drawings or FIGS. are supportive and descriptive of the disclosure, but the scope of the disclosure is defined solely by the claims. While some of the best modes and other embodiments for carrying out the claimed disclosure have been described in detail, various alternative designs and embodiments exist for practicing the disclosure defined in the appended claims. Furthermore, the embodiments shown in the drawings or the characteristics of various embodiments mentioned in the present description are not necessarily to be understood as embodiments independent of each other. Rather, it is possible that each of the characteristics described in one of the examples of an embodiment can be combined with one or a plurality of other desired characteristics from other embodiments, resulting in other embodiments not described in words or by reference to the drawings. Accordingly, such other embodiments fall within the framework of the scope of the appended claims.