A system and method for controlling braking in a saddle-type vehicle

Abstract

Disclosed is a system (300) and method for controlling braking in a saddle-type vehicle (100). The system (300) includes a force sensor (305) for measuring a force applied on brake lever (320) of vehicle (100), a traction control unit (310) for measuring a traction force experienced by a rear wheel (330b) of the vehicle (100), and a controller (315). The controller (315) is configured for, determining a friction braking torque applied to the rear wheel (330b), determining the traction force experienced by the rear wheel (330b), determining an electric torque for applying to the rear wheel (330b), and adjusting the electric torque based on the friction braking torque applied to the rear wheel (330b) and the traction force experienced by the rear wheel (330b) for controlling the braking in the saddle-type vehicle (100).

Description

A SYSTEM AND METHOD FOR CONTROLLING BRAKING IN A SADDLE- TYPE VEHICLETECHNICAL FIELD

[0001] The present disclosure generally relates to the field of braking in saddle-type vehicles, and more particularly to a system and method for controlling braking in a saddle-type vehicle.BACKGROUND

[0002] A combined braking system, generally known as combi-braking system, is a system that links front and rear brakes of a saddle-type vehicle such as motorcycles and scooters. In combi-braking system, a rider’s action of depressing one of the brake levers applies both front and rear brakes. When a rider depresses the combi-brake lever, for example the left-hand brake lever, the combi-braking system automatically allocates an appropriate amount of force to both the front wheel and the rear wheel based on a preset biasing mechanism. By combining the application of the front brake and the rear brake, the combi-braking system significantly improves the overall braking efficiency and provides better deceleration.

[0003] However, the implementation of combi-braking systems in saddle-type vehicles comes with certain disadvantages. For example, the application of brake force often leads to over-braking if not handled carefully, especially by inexperienced riders. Further, even though the combi-braking systems are better than rear only brake application, the systems still under utilize the total braking potential of the combined front and rear braking systems. Furthermore, the application of the brake force often reduces the amount of energy that can be recaptured using a regenerative braking system. Furthermore, the combi-braking systems activate both the front and the rear brakes, and the regenerative braking is generally less effective at low speeds and during light braking. This may not allow enough force to be directed to the regenerative system, thereby reducing effectiveness and overall energy recovery.

[0004] Hence, there is a need for a solution to overcome above mentioned drawbacks of the conventional combi -braking systems and hence to control braking in a saddle-type vehicle.BRIEF SUMMARY

[0005] This summary is provided to introduce a selection of concepts in a simple manner that is further described in the detailed description of the disclosure. This summary is not intended to identify key or essential inventive concepts of the subject matter nor is it intended for determining the scope of the disclosure.

[0006] To overcome or mitigate at least one of the problems mentioned above, there exists a need for a system and a method for controlling braking in a saddle-type vehicle.

[0007] A system for controlling braking in a saddle-type vehicle is disclosed. The system includes a force sensor configured for measuring a force applied on brake levers of the saddletype vehicle and a traction control unit configured for measuring a traction force experienced by a rear wheel of the saddle-type vehicle. The system further includes a controller communicatively connected to the force sensor and the traction control unit. The controller determines a friction braking torque applied to the rear wheel of the saddle-type vehicle, determines the traction force experienced by the rear wheel and determines an electric torque for applying to the rear wheel of the saddle-type vehicle. Then, the controller adjusts electric torque based on the friction braking torque applied to the rear wheel and the traction force experienced by the rear wheel for controlling the braking in the saddle-type electric vehicle.

[0008] Further disclosed is a method for controlling braking in a saddle-type vehicle. The method includes, determining a friction braking torque applied to a rear wheel of the saddletype vehicle, determining a traction force experienced by the rear wheel, determining an electric torque for applying to the rear wheel of the saddle-type vehicle, and adjusting the electric torque based on the friction braking torque applied to the rear wheel and the traction force experienced by the rear wheel for controlling the braking in the saddle-type electric vehicle.

[0009] To further clarify advantages and features of the present disclosure, a more particular description of the disclosure will be rendered by reference to specific embodiments thereof, which is illustrated in the appended figures. It is to be appreciated that these figures depict only typical embodiments of the disclosure and are therefore not to be considered limiting of its scope. The disclosure will be described and explained with additional specificity and detail with the accompanying figures.BRIEF DESCRIPTION OF THE FIGURES

[0010] The disclosed method and system will be described and explained with additional specificity and detail with the accompanying figures in which:

[0011] Figure 1 illustrates an electric automotive ecosystem including an electric vehicle and a charging infrastructure connected to the electric vehicle;

[0012] Figure 2A illustrates a brake distribution graph representing the relationship between front and rear braking forces of a saddle-type vehicle under different conditions;

[0013] Figure 2B illustrates a brake distribution graph showing ideal braking curve and preset biasing line;

[0014] Figure 3A depicts a block diagram illustrating a system for controlling braking in a saddle-type vehicle, in accordance with an embodiment of the present disclosure;

[0015] Figure 3B depicts a block diagram illustrating the system and other elements of the saddle-type vehicle for controlling braking in the saddle-type vehicle, in accordance with an embodiment of the present disclosure;

[0016] Figure 4A depicts a brake distribution graph illustrating the relationship between front and rear braking forces of a saddle-type vehicle, in accordance with an embodiment of the present disclosure;

[0017] Figure 4B depicts a brake distribution graph illustrating the effect of the positive electric torque, in accordance with an embodiment of the present disclosure;

[0018] Figure 4C depicts a brake distribution graph illustrating the effect of the negative electric torque, in accordance with an embodiment of the present disclosure;

[0019] Figures 5A to 5F depict different brake force distribution ratios between the front wheel and the rear wheel of the saddle-type vehicle, in accordance with an embodiment of the present disclosure; and

[0020] Figure 6 depicts a flowchart illustrating a method controlling braking in a saddle-type vehicle, in accordance with an embodiment of the present disclosure.

[0021] Further, persons skilled in the art to which this disclosure belongs will appreciate that elements in the figures are illustrated for simplicity and may not have been necessarily drawn to scale. Furthermore, in terms of the construction of the joining ring and one or more components of the bearing assembly may have been represented in the figures by conventional symbols, and the figures may show only those specific details that are pertinent to understanding the embodiments of the present disclosure so as not to obscure the figures with details that will be readily apparent to those of ordinary skill in the art having benefit of the description herein.DETAILED DESCRIPTION

[0022] For the purpose of promoting an understanding of the principles of the present disclosure, reference will now be made to the various embodiments and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the present disclosure is thereby intended, such alterations and further modifications in the illustrated system, and such further applications of the principles of the present disclosure as illustrated therein being contemplated as would normally occur to one skilled in the art to which the present disclosure relates.

[0023] It will be understood by those skilled in the art that the foregoing general description and the following detailed description are explanatory of the present disclosure and are not intended to be restrictive thereof.

[0024] Whether or not a certain feature or element was limited to being used only once, it may still be referred to as “one or more features” or “one or more elements” or “at least one feature” or “at least one element.” Furthermore, the use of the terms “one or more” or “at least one” feature or element do not preclude there being none of that feature or element, unless otherwise specified by limiting language including, but not limited to, “there needs to be one or more. . . ” or “one or more elements is required.”

[0025] Reference is made herein to some “embodiments.” It should be understood that an embodiment is an example of a possible implementation of any features and / or elements of the present disclosure. Some embodiments have been described for the purpose of explaining one or more of the potential ways in which the specific features and / or elements of the proposed disclosure fulfil the requirements of uniqueness, utility, and non-obviousness.

[0026] Use of the phrases and / or terms including, but not limited to, “a first embodiment,” “a further embodiment,” “an alternative embodiment,” “one embodiment,” “an embodiment,” “multiple embodiments,” “some embodiments,” “other embodiments,” “further embodiment”, “furthermore embodiment”, “additional embodiment” or other variants thereof do not necessarily refer to the same embodiments. Unless otherwise specified, one or more particular features and / or elements described in connection with one or more embodiments may be found in one embodiment, or may be found in more than one embodiment, or may be found in all embodiments, or may be found in no embodiments. Although one or more features and / or elements may be described herein in the context of only a single embodiment, or in the context of more than one embodiment, or in the context of all embodiments, the features and / or elements may instead be provided separately or in any appropriate combination or not at all. Conversely, any features and / or elements described in the context of separate embodiments may alternatively be realized as existing together in the context of a single embodiment.

[0027] Any particular and all details set forth herein are used in the context of some embodiments and therefore should not necessarily be taken as limiting factors to the proposed disclosure.

[0028] The terms “comprises”, “comprising”, or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process or method that comprises a list of steps does not include only those steps but may include other steps not expressly listed or inherent to such process or method. Similarly, one or more devices or sub-systems or elements or structures or components proceeded by “comprises... a” does not, without more constraints, preclude the existence of other devices or other sub-systems or other elements or other structures or other components or additional devices or additional sub-systems or additional elements or additional structures or additional components.

[0029] Embodiments of the present disclosure will be described below in detail with reference to the accompanying drawings.

[0030] For the sake of clarity, the first digit of a reference numeral of each component of the present disclosure is indicative of the Figure number, in which the corresponding component is shown. For example, reference numerals starting with digit “1” are shown at least in Figure 1. Similarly, reference numerals starting with digit “2” are shown at least in Figure 2.

[0031] Embodiments of the present disclosure disclose a system and a method for controlling braking in a saddle-type vehicle. The system includes a force sensor configured for measuring a force applied on brake levers of the saddle-type vehicle, a traction control unit configured for measuring a traction force experienced by a rear wheel of the saddle-type vehicle and a controller communicatively connected to the force sensor and the traction control unit. In one embodiment, the controller determines friction braking torque applied to the rear wheel of the saddle-type vehicle, determines the traction force experienced by the rear wheel and determines an electric torque for applying to the rear wheel of the saddle-type vehicle. Then the microcontroller adjusts the electric torque based on the friction braking torque applied to the rear wheel and the traction force experienced by the rear wheel for controlling the braking in the saddle-type electric vehicle. Adjusting the electric torque includes providing a negative electric torque and maintaining the negative electric torque within a maximum traction force experienced by the rear wheel, based on the friction braking torque applied to the rear wheel and the traction force experienced by the rear wheel. Further, adjusting the electric torque includes providing a positive electric torque if the traction force experienced by the rear wheel is less than the friction braking torque applied to the rear wheel, for achieving a maximum deceleration rate and to avoid the rear wheel lock up.

[0032] It is important to note that while the elements of the system and functionalities discussed are presented in the context of an electric vehicle, the system and method disclosed herein may be implemented with internal combustion (IC) engine vehicles with minor modifications.

[0033] As the system and its functionalities are discussed within the framework of electric vehicles, Figure 1 is presented to establish this context. Figure 1 illustrates an electric automotive ecosystem including an electric vehicle and a charging infrastructure connected to the electric vehicle. In construction, the electric vehicle (EV) 100 typically includes a battery or battery pack 105 enclosed within a battery casing and includes a Battery Management System (BMS), an on-board charger 110, a Motor Controller Unit (MCU), an electric motor 115 and an electric transmission system 120. The primary functions of the above-mentioned elements are detailed in the following paragraphs: The battery of an EV 100 (also known as Electric Vehicle Battery (EVB) or traction battery) is re-chargeable and is the primary source of energy required for the operation of the EV, wherein the battery 105 is typically charged using the electric power from the grid through a charging infrastructure 125. The battery maybe charged using Alternating Current (AC) or Direct Current (DC), wherein, in case of AC input, the on-board charger 110 converts the AC power to DC power after which the DC power is transmitted to the battery through the BMS. However, in case of DC charging, the on-board charger 110 may be bypassed, and the current transmitted directly to the battery through the BMS. Additionally, the EV 100 may also be equipped with wired or wireless or wired and wireless infrastructure such as, but not limited to Bluetooth, Wi-Fi, controller area network (CAN), Ethernet, Universal Serial Bus (USB), universal asynchronous receiver / transmitter (UART), Local Area network (LIN), Inter-Integrated Circuit (I2C), serial peripheral interface (SPI), Synchronous Serial Interface (SSI) and so on to facilitate wireless communication with the charging infrastructure 125, other EVs or the cloud.

[0034] The battery 105 is made up of a plurality of cells which are grouped into a plurality of modules. The terms “battery”, and “battery pack” may be used interchangeably and may refer to any of a variety of different rechargeable cell compositions and configurations including, but not limited to, lithium-ion (e.g., lithium iron phosphate, lithium cobalt oxide, other lithium metal oxides, etc.), lithium-ion polymer, nickel metal hydride, nickel cadmium, nickel hydrogen, nickel-zinc, silver zinc, or other battery types or configurations. The term “battery pack” as used herein may refer to multiple individual batteries enclosed within a single structure or multi-piece structure. The individual batteries may be electrically interconnected to achieve a desired voltage and current capacity for a desired application. The Battery Management System (BMS) is an electronic system, the primary function of which is to ensure that the battery 105 is operating safely and efficiently. The BMS continuously monitors different parameters of the battery such as temperature, voltage, current and so on, and communicates these parameters to the Electronic Control Unit (ECU) and the Motor Controller Unit (MCU) in the EV using one or more protocols including but not limited to, Controller Area Network (CAN) bus protocol which facilitates the communication between the ECU and MCU and other peripheral elements of the EV 100 without the requirement of a host computer.

[0035] The MCU primarily controls or regulates the operation of the electric motor based on the power transmitted from the vehicle’s battery, wherein the primary functions of the MCU include starting the electric motor 115, stopping the electric motor 115, controlling the speed of the electric motor 115, enabling the vehicle to move in the reverse direction and protect the electric motor 115 from premature wear and tear. The primary function of the electric motor 115 is to convert electrical energy into mechanical energy, wherein the converted mechanicalenergy is subsequently transferred to the transmission system of the EV to facilitate movement of the EV. Additionally, the electric motor 115 also acts as a generator during regenerative braking (that is, kinetic energy of the EV in motion is converted into electrical energy and stored in the battery of the EV). The types of motors generally employed in EVs include, but are not limited to DC series motor, Brushless DC motor (also known as BLDC motors), Permanent Magnet Synchronous Motor (PMSM), Three Phase AC Induction Motors and Switched Reluctance Motor (SRM).

[0036] The transmission system 120 of the EV 100 facilitates the transfer of the generated mechanical energy by the electric motor 115 to the wheels (130a, 130b) of the EV. Generally, the transmission systems 120 used in EVs include single speed transmission system and multispeed (i.e., two-speed) transmission system, wherein the single speed transmission system includes a single gear pair whereby the EV runs at a constant speed ratio between the motor rotational speed and the wheel rotational speed. However, the multi-speed / two-speed transmission system includes different gear ratios which facilitates higher torque and vehicle speed depending on the selected gear ratio.

[0037] In one embodiment, all data pertaining to the EV 100 or charging infrastructure 125 or both, are collected and processed using a remote server (known as cloud) 135, wherein the processed data is indicated to the rider of the EV 100 through a display unit present in the dashboard 140 of the EV 100. In an embodiment, the display unit may be an interactive or touch sensitive display unit. In another embodiment, the display unit may be a non-interactive display unit. It is noteworthy that the electric vehicle, as described with reference to Figure 1, provides a context in which various embodiments of the present disclosure may be described and observed. Subsequently, the embodiments of the present disclosure are described by referring to the essential elements and the structure of an electric vehicle.

[0038] As described, the system for controlling the braking in the saddle -type vehicle includes a force sensor, a traction control unit and a controller communicatively connected to the force sensor and the traction control unit. In one embodiment, the controller determines friction braking torque applied to the rear wheel of the saddle-type vehicle, determines the traction force experienced by the rear wheel and determines an electric torque for applying to the rear wheel of the saddle-type vehicle. Then the microcontroller adjusts the electric torque based on the friction braking torque applied to the rear wheel and the traction force experiencedby the rear wheel for controlling the braking in the saddle-type electric vehicle. Adjusting the electric torque includes providing a negative electric torque and maintaining the negative electric torque within a maximum traction force experienced by the rear wheel, based on the friction braking torque applied to the rear wheel and the traction force experienced by the rear wheel. Further, adjusting the electric torque includes providing a positive electric torque if the traction force experienced by the rear wheel is less than the friction braking torque applied to the rear wheel, for achieving a maximum deceleration rate and to avoid the rear wheel lock up. Hence, the system disclosed in the present disclosure facilitates dynamic brake biasing by adjusting the electric torque applied to the rear wheel of the saddle-type vehicle.

[0039] Before detailing the elements and functionalities of the system, the concepts of the ideal braking curve and brake distribution are explained to establish the context for this disclosure. Figure 2A illustrates a brake distribution graph representing the relationship between front and rear braking forces of a saddle-type vehicle under different conditions. As shown, x-axis represents a front braking force and y-axis represents a rear braking force. The ideal braking curve 205 shows an optimal distribution of braking forces between the front and rear wheels. Following the ideal braking curve 205 allows the saddle-type vehicle 100 to achieve the maximum possible deceleration without wheel lock-up under any loading conditions. Further, negative 45-degree lines labeled with values (0.2g, 0.4g, up to 1g) represent a grid of constant braking force (the sum of front and rear braking forces) and thus constant deceleration. Furthermore, friction coefficient (p) between the tires and the road surface is shown by the dotted lines. Furthermore, two sets of lines 210 and 215 which are truncated where the line of constant friction for the front wheel 130a meets the rear wheel 130b. As shown, the ideal braking curve 205 is the intersection of the two sets of lines 210 and 215 for the front wheel 130a and the rear wheel 130b.

[0040] Considering the conventional combi-braking system with preset biasing disclosed in the background, the braking system's performance is restricted to utilizing only a portion of the maximum potential of the braking system. Referring to Figure 2A, the brake bias is limited to a line that must always be above the ideal braking curve 205. Figure 2B illustrates a brake distribution graph showing ideal braking curve and preset biasing line. As shown, if the brake bias is limited to a maximum forward bias equal to the nominal weight distribution of the vehicle (for example, 70% rear and 30% front), then the system may only apply a maximum of 52% of the total braking force. The line 220 represents a preset biasing line, for example70%rear and 30% front. Hence, the system achieves a portion of the max possible deceleration, whereas with proper utilization of brake distribution, a greater deceleration can be achieved.

[0041] Embodiments of the present disclosure provides a system and a method for achieving maximum deceleration by dynamically adjusting the electric torque applied to the rear wheel 130b of the saddle-type vehicle 100 based on the friction braking torque applied to the rear wheel 130b and the traction force experienced by the rear wheel 130b. To achieve this, the mechanical system is designed to provide friction brakes to the front wheel 130a and the rear wheel 130b such that a line representing the friction brakes always above the ideal braking curve 205. In one embodiment, the same is achieved using a delay mechanism along with standard proportioning mechanism. For example, when a rider activates the brake lever, the delay mechanism ensures that the rear brake is applied first. The delay mechanism may be implemented through hydraulic circuits, mechanical linkages, or electronic controls that prioritize the rear brake. After a predefined delay, the front brake is engaged. The delay allows the rear brake to begin decelerating the saddle-type vehicle 100, which helps in maintaining stability and reduces the risk of the front wheel 130a locking up.

[0042] Figure 3A depicts a block diagram illustrating a system for controlling braking in a saddle-type vehicle, in accordance with an embodiment of the present disclosure. Figure 3B depicts a block diagram illustrating the system and other elements of the saddle-type vehicle for controlling braking in the saddle-type vehicle, in accordance with an embodiment of the present disclosure. Referring to Figures 3A and 3B, the system 300 for controlling braking in the saddle-type vehicle 100 includes a force sensor 305, a traction control unit 310 and a controller 315, wherein the controller 315 is connected to the force sensor 305 and the traction control unit 310. Further, referring to Figure 3B, the other elements of the saddle-type vehicle 100 includes but not limited to a brake lever 320, a motor 325, a front wheel 330a, a rear wheel 330b, friction brakes 335, a throttle sensor 345, and other sensors 350. It is to be noted that the one or more elements described with reference to Figure 1 and Figure 3B may be the same, however, the reference numerals have been changed for the sake of clarity.

[0043] The force sensor 305 is configured to detect an amount of pressure or force applied to the brake lever 320 of the saddle-type vehicle 100. It is to be noted the brake lever 320, as described herein, refers to the left brake lever of the saddle-type vehicle 100, which is used by the combi-braking systems. However, combination of two brake levers (left and right) may be used for dynamically adjusting the electric torque applied to the rear wheel 330b of the saddle-type vehicle 100. For the sake of explanation and understanding, input from the left brake lever of the saddle-type vehicle 100 is considered in the present disclosure.

[0044] The traction control unit 310 is configured for detecting loss of traction and estimating the traction force experienced by the rear wheel 330b. Hence, the traction control unit 310 may include force sensors, wheel speed sensors, throttle position sensors, etc. In one embodiment of the present disclosure, the traction control unit 310 estimates the traction force experienced by the rear wheel 330b and the traction limit. In one implementation, wheel speed sensors are used to monitor the rotational speeds of both the front wheel 330a and the rear wheel 330b. In another implementation, inertial measurement units (IMUs) based sensors are used to detect changes in vehicle dynamics, such as changes in pitch, roll, and yaw angles, which may indicate loss of traction. Further, one or more algorithms may be used to analyze the IMU data to estimate the traction loss experienced by the rear wheel 330b or the traction limit of the rear wheel 330b.

[0045] In one embodiment, the controller 315 is configured for controlling braking in the saddle-type vehicle 100 based on the friction braking torque applied to the rear wheel 330b and the traction force experienced by the rear wheel 330b. Accordingly, the controller 315 may be a motor controller of the saddle-type vehicle 100 configured to control the braking in the saddle-type vehicle 100 or a dedicated controller may be used in conjunction with the motor controller of the saddle-type vehicle 100 for controlling the braking in the saddle-type vehicle 100.

[0046] As described, the system 300 is configured for achieving maximum deceleration of the saddle-type vehicle 100 by dynamically adjusting the electric torque applied to the rear wheel 330b of the saddle-type 100. Referring to Figure 3B, initially, a force applied on the brake lever 320 of the saddle-type vehicle 100 is measured using the force sensor 305 and communicated to the controller 315. It is to be noted that the mechanical system having friction brakes 335 is used to provide friction brakes to the front wheel 330a and the rear wheel 330b such that a line representing the friction brakes is always above the ideal braking curve 205. Figure 4A depicts a brake distribution graph illustrating the relationship between front and rear braking forces of a saddle-type vehicle, in accordance with an embodiment of the present disclosure. As shown, the line 405 represents the friction brakes applied to the front wheel 330a and the rear wheel 330b is above the ideal braking curve 205.

[0047] Then the system 300 measures the traction force experienced by the rear wheel 330b of the saddle-type vehicle 100 using the traction control unit 315. That is, the system 300 measures the traction limit of the rear wheel 330b.

[0048] In one embodiment of the present disclosure, upon measuring the force applied on brake lever 320 and the traction force experienced by the rear wheel 330b, the controller 315 determines a friction braking torque applied to the rear wheel 330b by measuring the load applied to the brake lever 320, wherein the load measurement may performed using a load cell in one embodiment of the present disclosure. Further, the controller 315 determines the traction limit of the rear wheel 330b using the traction control unit 310. Further, in one embodiment of the present disclosure, the microcontroller 315 determines an electric torque for applying to the rear wheel 330b of the saddle-type vehicle 110. In one implementation, the electric torque for applying to the rear wheel 330b is determined based on the friction braking torque applied to the rear wheel 330b and the traction force experienced by the rear wheel 330b, that is, the traction limit. In another implementation, the electric torque is determined based on a force applied on brake lever 320 of the saddle-type vehicle 100 and a lookup table associating brake force values with corresponding electric braking torque values.

[0049] Further, the controller 315 dynamically adjusts the electric torque applied to rear wheel 330b based on the friction braking torque applied to the rear wheel 330b and the traction force experienced by the rear wheel 330b for controlling the braking in the saddle-type electric vehicle 100. Referring to Figure 3B, based on the friction braking torque applied to the rear wheel 330b and the traction force experienced by the rear wheel 330b the controller 315 modulates the electric current supplied to the motor 325, controlling the torque generated, and the motor 325 applies the controlled torque directly to the rear wheel 330b. In another embodiment of the present disclosure, input from the throttle sensor 345 and input from the other sensors of the vehicle (indicating the driving mode, for example) also considered for dynamically adjusts the electric torque applied to rear wheel 330b.

[0050] In one embodiment, adjusting the electric torque includes providing a negative electric torque and maintaining the negative electric torque within the maximum traction force experienced by the rear wheel 330b, based on the friction braking torque applied to the rear wheel 330b and the traction force experienced by the rear wheel 330b. The maximum traction force experienced by the rear wheel 330b as described herein refers to the maximum tractionlimit, beyond which the rear wheel 330b will skid. The term negative electric torque as described herein refers to a positive braking torque or regenerative braking.

[0051] Referring to Figure 4A, the line 405 represents the friction brakes applied to the front wheel 330a and the rear wheel 330b and the line 405 is above the ideal braking curve 205. In one embodiment, the controller 315 provides the negative electric torque and maintains the negative electric torque within the maximum traction limit of the rear wheel 330b, based on the friction braking torque applied to the rear wheel 330b and the maximum traction limit of the rear wheel 330b. Referring to Figure 4A, the controller 315 provides the negative electric torque and maintains the negative electric torque within the maximum traction limit of the rear wheel 330b as shown by the arrows 410. As shown, from p = 0.4 to p = 1, the controller 310 increases the negative electric torque and maintains the negative electric torque within the maximum traction limit of the rear wheel 330b, that is, p = 1. Since regenerative brake may be controlled by the system 300, the arrows 410 may expand and contract to not cross the maximum traction available, that is, p = 1. Hence, the system 300 may apply 75% of the total braking force, achieving a maximum deceleration of only 0.75g.

[0052] As described, in another embodiment, adjusting the electric torque includes providing a positive electric torque if the traction force experienced by the rear wheel 330b is less than the friction braking torque applied to the rear wheel 330b, for achieving a maximum deceleration rate. The term positive electric torque as described herein refers to a positive motor torque for driving the motor 320.

[0053] Figure 4B depicts a brake distribution graph illustrating the effect of the positive electric torque, in accordance with an embodiment of the present disclosure. As shown, the line 405 represents the friction brakes applied to the front wheel 330a and the rear wheel 330b and the line 405 is above the ideal braking curve 205. In one embodiment, the controller 315 provides the positive electric torque to drive the motor 325 as shown by the arrows 415, if the traction force experienced by the rear wheel 330b is less than the friction braking torque applied to the rear wheel 330b, for achieving a maximum deceleration rate.

[0054] As shown, from p = 0.4 to p = 1.0, the controller 310 increases the positive electric torque, which in turn opposes the friction brake, for achieving the maximum deceleration rate, for example 1g.

[0055] As described, the system 300 disclosed in the present disclosure facilitates dynamic brake biasing by adjusting the electric torque applied to the rear wheel 330b of the saddle-type vehicle 100. By adjusting the electric torque applied to the rear wheel 330b, as disclosed in the present disclosure, prevents the wheels from locking up, reduces the risk of skidding, and significantly improves the overall braking efficiency and safety for riders, especially in varied road conditions.

[0056] Further, in one embodiment of the present disclosure, the system 300 disclosed in the present disclosure may be implemented to efficiently utilize the regenerative braking. For example, regenerative braking can be effectively utilized by providing negative electric torque, which significantly contributes to the braking of the saddle-type vehicle 100. Figure 4C depicts a brake distribution graph illustrating the effect of the negative electric torque, in accordance with an embodiment of the present disclosure. As shown, by adjusting the mechanical system such that the line 405 representing the friction brakes is below the ideal braking curve 205, the negative electric torque is provided to the rear wheel 330b to provide the total braking force and bias. Such an implementation facilitates maximizing the overall performance when working with low torque regenerative braking systems.

[0057] In one embodiment of the present disclosure, the system 300 is configured for dynamically adjusting the electric torque applied to the rear wheel 330b of the saddle-type 100 based on the brake bias or a brake force distribution ratio, in addition to the friction braking torque applied to the rear wheel 330b and the traction force experienced by the rear wheel 330b. Figures 5A to 5F depict different brake force distribution ratios between the front wheel and the rear wheel of the saddle-type vehicle, in accordance with an embodiment of the present disclosure. The arrow 505 indicates the brake force distribution ratio between the front wheel 330a and the rear wheel 330b of the saddle-type vehicle 100. Referring to Figure 5A, the arrow 505 indicates a ratio of 15:85, indicating that the 85% of the force being applied to the rear wheel 330b and the remaining 15% of the force being applied to the front wheel 330a. Similarly, the arrow 505 in Figures 5B to 5F represents the brake force distribution ratio of 35:65, 45:55, 55:45, 65:35 and 85: 15 respectively. Referring to Figure 5C, the system 300 provides the negative electric torque and maintains the negative electric torque within the maximum traction force experienced by the rear wheel 330b, as indicated by the lines 510, when the force being applied to the rear wheel 330b is equal to and greater than 45%.

[0058] As described, the system 300 disclosed in the present disclosure facilitates dynamic brake biasing by adjusting the electric torque applied to the rear wheel 330b of the saddle-type vehicle 100. Figure 6 depicts a flowchart illustrating a method controlling braking in a saddletype vehicle, in accordance with an embodiment of the present disclosure. Initially, at step 605, the controller 315 the friction braking torque applied to the rear wheel 330b of the saddle-type vehicle 100. In one embodiment, the friction braking torque applied to the rear wheel 330b is determined by measuring the load applied to the brake lever 320, wherein the load measurement may performed using a load cell.

[0059] At step 610, the controller 315 determines the traction force experienced by the rear wheel 330b. In one implementation, controller 315 utilizes the traction control unit 310 for detecting loss of traction and for estimating the traction force experienced by the rear wheel 330b. The traction control unit 310 may include but not limited to force sensors, wheel speed sensors, throttle position sensors, etc. The traction force experienced by the rear wheel 330b also indicates the traction limit, beyond which the rear wheel 330b will skid.

[0060] At step 615, the controller 315 determines the electric torque for applying to the rear wheel 330b of the saddle-type vehicle 100. In one implementation, the electric torque is determined based on the friction braking torque applied to the rear wheel 330b and the traction force experienced by the rear wheel 330b. In another implementation, the electric torque is determined based on the force applied on brake lever 320 of the saddle-type vehicle 100 and a lookup table associating brake force values with corresponding electric braking torque values.

[0061] At step 620, the controller 315 adjusts the electric torque based on the friction braking torque applied to the rear wheel 330b and the traction force experienced by the rear wheel 330b for controlling the braking in the saddle-type vehicle 100. In one embodiment, adjusting the electric torque includes providing the negative electric torque and maintaining the negative electric torque within the maximum traction force experienced by the rear wheel 330b, based on the friction braking torque applied to the rear wheel 330b and the traction force experienced by the rear wheel 330b. Further, adjusting the electric torque includes providing the positive electric torque if the traction force experienced by the rear wheel 330b is less than the friction braking torque applied to the rear wheel 330b, for achieving the maximum deceleration rate.

[0062] The system and method disclosed in the present disclosure facilitates overall energy recovery by dynamically adjusting the electric torque applied to the rear wheel 130b of thesaddle-type vehicle 100. Even though the present disclosure is directed towards the saddle-type electric vehicle, the system and method may be implanted with saddle-type vehicles with internal combustion (IC) engines with minor modifications.

[0063] While specific language has been used to describe the disclosure, any limitations arising on account of the same are not intended. As would be apparent to a person skilled in the art, various working modifications may be made to the method in order to implement the inventive concept as taught herein.

[0064] The figures and the foregoing description give examples of embodiments. Those skilled in the art will appreciate that one or more of the described elements may well be combined into a single functional element. Alternatively, certain elements may be split into multiple functional elements. Elements from one embodiment may be added to another embodiment. For example, orders of processes described herein may be changed and are not limited to the manner described herein. Moreover, the actions of any flow diagram need not be implemented in the order shown; nor do all of the acts necessarily need to be performed. Also, those acts that are not dependent on other acts may be performed in parallel with the other acts. The scope of embodiments is by no means limited by these specific examples. Numerous variations, whether explicitly given in the specification or not, such as differences in structure, dimension, and use of material, are possible. The scope of embodiments is at least as broad as given by the following claims.

Claims

CLAIMS:

1. A system (300) for controlling braking in a saddle-type vehicle (100), the system comprises: a force sensor (305) configured for measuring a force applied on brake lever (320) of the saddle -type vehicle (100); a traction control unit (310) configured for measuring a traction force experienced by a rear wheel (330b) of the saddle-type vehicle (100); and a controller (315) communicatively connected to the force sensor (305) and the traction control unit (310), wherein the controller (315) is configured for: determining a friction braking torque applied to the rear wheel (330b) of the saddle-type vehicle (100); determining the traction force experienced by the rear wheel (330b); determining an electric torque for applying to the rear wheel (330b) of the saddle-type vehicle (100); and adjusting the electric torque based on the friction braking torque applied to the rear wheel (330b) and the traction force experienced by the rear wheel (330b) for controlling the braking in the saddle-type vehicle (100).

2. The system (300) as claimed in claim 1, wherein the controller (315) determines the electric torque based on the friction braking torque applied to the rear wheel (330b) and the traction force experienced by the rear wheel (330b).

3. The system (300) as claimed in claim 1, wherein adjusting the electric torque, by the controller (315), comprises providing a negative electric torque and maintaining the negative electric torque within a maximum traction force experienced by the rear wheel (330b), based on the friction braking torque applied to the rear wheel (330b) and the traction force experienced by the rear wheel (330b).

4. The system (300) as claimed in claim 1, wherein adjusting the electric torque, by the controller (315), comprises providing a positive electric torque if the traction force experienced by the rear wheel (330b) is less than the friction braking torque applied to the rear wheel (330b), for achieving a maximum deceleration rate.

5. A method for controlling braking in a saddle-type vehicle (100), the method comprising:determining, by a controller (315), a friction braking torque applied to a rear wheel (330b) of the saddle-type vehicle (100); determining, by the controller (315), a traction force experienced by the rear wheel (330b); determining, by the controller (315), an electric torque for applying to the rear wheel (330b) of the saddle-type vehicle (100); and adjusting, by the controller (315), the electric torque based on the friction braking torque applied to the rear wheel (330b) and the traction force experienced by the rear wheel (330b) for controlling the braking in the saddle-type vehicle (100).

6. The method as claimed in claim 5, wherein determining the traction force experienced by the rear wheel (330b) comprises measuring the traction force using a traction control unit (310).

7. The method as claimed in claim 5, wherein the electric torque is determined based on the friction braking torque applied to the rear wheel (330b) and the traction force experienced by the rear wheel (330b).

8. The method as claimed in claim 5, wherein adjusting the electric torque comprises providing a negative electric torque and maintaining the negative electric torque within a maximum traction force experienced by the rear wheel(330b), based on the friction braking torque applied to the rear wheel (330b) and the traction force experienced by the rear wheel (330b).

9. The method as claimed in claim 5, wherein adjusting the electric torque comprises providing a positive electric torque if the traction force experienced by the rear wheel (330b) is less than the friction braking torque applied to the rear wheel (330b), for achieving a maximum deceleration rate.

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