Patent Publication Number: US-10322770-B1

Title: Electricity aided bicycle and auxiliary power controlling method thereof

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to an electricity aided bicycle, and particularly relates to an auxiliary power controlling method for an electricity aided bicycle capable of calculating a reliable estimated speed. 
     2. Description of Related Art 
     In the design of control over an auxiliary motor of an electricity aided bicycle in the known art, the velocity is detected and converted into a pedaling torque force based on Newton&#39;s Second Law of Motion (F=ma), and an auxiliary force is supplied at a ratio of 1:1. However, based on such calculation, an unstable detection signal may be obtained through the velocity detection in the known art when the user rides uphill or on an unstable ground. In the obtained detection signal, the acceleration (a) may be discontinuous values, so the pedaling force (F) obtained through calculation is also unstable. Hence, the auxiliary motor of the electricity aided bicycle is unable to output an optimal auxiliary force to properly help the user. Also, when there is a greater error in the calculation of the pedaling force, the auxiliary force output by the auxiliary motor may be excessive, and such power may disturb or even hurt the user. 
     SUMMARY OF THE INVENTION 
     One or some embodiments of the invention provides an electricity aided bicycle and an auxiliary power controlling method thereof capable of providing a stable auxiliary force when a movement velocity is low. 
     An electricity aided bicycle according to an embodiment of the invention includes a driving circuit, a rotating speed detector and a command voltage generator. The driving circuit receives a command voltage, and drives an auxiliary motor of the electricity aided bicycle based on the command voltage. The rotating speed detector generates a detection signal having a plurality of pulses based on a rotation status of a driving gear of the electricity aided bicycle. The command voltage generator is coupled to the rotating speed detector and the driving circuit. The command voltage generator receives the detection signal, and is configured to: calculate times between two adjacent pulses in the detection signal, operate numerical value derivation operation based on the times to generate an estimated velocity value, set an electricity aid strategy table and calculate the command voltage based on the estimated velocity value and the electricity aid strategy table. The electricity aid strategy table records a relation between an electricity aid ratio and the estimated velocity value. 
     An auxiliary power controlling method according to an embodiment of the invention is adapted for an electricity aided bicycle. The controlling method includes: generating a detection signal having a plurality of pulses based on a rotation status of a driving gear of the electricity aided bicycle; calculating a plurality of times between two adjacent pulses in the pulses of the detection signal; performing a numerical value derivation operation based on the times to generate an estimated velocity value; and setting an electricity aid strategy table to calculate the command voltage based on the estimated velocity value and the electricity aid strategy table. In addition, the electricity aid strategy table records a relation between an electricity aid ratio and the estimated velocity value. 
     Based on the above, in the embodiments of the invention, the detection signal is generated by detecting the rotation status of the driving gear, the times between the adjacent pulses in the detection signal are calculated, and the numerical value derivation operation is performed based on the times to obtain the estimated velocity value. In addition, the command voltage is calculated based on the estimated velocity value with reference to the electricity aid strategy table. Accordingly, a stable command voltage may be generated under a condition that the electricity aided bicycle is at a low movement velocity, and the auxiliary motor may generate a stable auxiliary power to make riding more comfortable. 
     To make the above features and advantages of the invention more comprehensible, embodiments accompanied with drawings are described in detail as follows. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
         FIG. 1  is a block diagram illustrating an electricity aided bicycle according to an embodiment of the invention. 
         FIG. 2  is a schematic view illustrating signal detection according to an embodiment of the invention. 
         FIG. 3  is a schematic view illustrating a command voltage generator according to an embodiment of the invention. 
         FIG. 4  is a schematic view illustrating a command voltage generator according to another embodiment of the invention. 
         FIG. 5  is a schematic view illustrating a command voltage generator according to yet another embodiment of the invention. 
         FIG. 6  is a schematic view illustrating an electricity aid strategy according to an embodiment of the invention. 
         FIG. 7  is a schematic view illustrating an electricity aided bicycle according to another embodiment of the invention. 
         FIG. 8  is a flowchart illustrating an auxiliary power controlling method of an electricity aided bicycle according to an embodiment of the invention. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     Reference will now be made in detail to the present preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts. 
     Referring to  FIG. 1 ,  FIG. 1  is a block diagram illustrating an electricity aided bicycle according to an embodiment of the invention. An electricity aided bicycle  100  includes a driving circuit  110 , a rotating speed detector  120 , and a command voltage generator  130 . The driving circuit  110  is coupled to an auxiliary motor MOT of the electricity aided bicycle  100 , receives a command voltage V*, and drives the auxiliary motor MOT of the electricity aided bicycle  100  based on the command voltage V*. The rotating speed detector  120  detects a rotation status of a driving gear C 1  of the electricity aided bicycle  100  and generates a detection signal DS based on the rotation status of the driving gear C 1  of the electricity aided bicycle  100 . Moreover, the detection signal DS has a plurality of pulses. More specifically, when the driving gear C 1  of the electricity aided bicycle  100  rotates through pedaling of a rider, a pulse is generated in the detection signal DS in correspondence to each time when a rotation angle of the driving gear C 1  exceeds a predetermined angle. In other words, a fixed number of pulses are generated in the detection signal DS after one cycle of rotation of the driving gear C 1 . 
     Besides, in the embodiments of the invention, the command voltage generator  130  is coupled to the rotating speed detector  120  and the driving circuit  110 . The command voltage generator  130  receives the detection signal DS through the rotation detector  120 . In addition, the command voltage generator  130  calculates times between two adjacent pulses in the pulses of the detection signal DS and performs a numerical value derivation operation based on the plurality of times obtained, so as to generate an estimated velocity value. The command voltage generator  130  also sets an electricity aid strategy table and calculates the command voltage V* based on the estimated velocity value and the electricity aid strategy table. The electricity aid strategy table records a relation between an electricity aid ratio and the estimated velocity value. 
     To be more specific, referring to  FIGS. 1 and 2 ,  FIG. 2  is a schematic view illustrating signal detection according to an embodiment of the invention. During an initial period when the electricity aided bicycle is being started, or when the electricity aided bicycle is ridden uphill or on a non-flattened ground, the rotation of the driving gear C 1  may not be smooth and may be discontinuous. Thus, in the continuous pulses generated in the detection signal DS, the times between two adjacent pulses are not the same. A detection cycle with a fixed time interval may be set by the command voltage generator  130 . Based on the set detection cycle, the command voltage generator  130  may periodically detect whether a pulse is generated in the detection signal DS. in  FIG. 2 , starting from a detection starting point TS, the command voltage generator  130  may continuously detect whether a pulse is generated in the detection signal DS in a plurality of detection time intervals TD 1  to TDN. In addition, lengths of the time intervals TD 1  to TDN are fixed and equivalent to the set detection cycle. According to an embodiment of the invention, the detection cycle may be set at one millisecond. Of course, in other embodiments of the invention, the detection cycle may be set differently by the designer based on an actual status of the electricity aided bicycle without any specific limitation. 
     In the time interval TD 1 , no pulse is generated in a detection signal DS 1 . In the subsequent time interval TD 2 , a pulse PS 1  is generated in the detection signal DS 1 . Under the circumstance, the command voltage generator  130  may calculate time required from the starting point TS to the time when the pulse PS 1  is generated to obtain a time T K−2 . 
     The command voltage generator  130  may continuously detect the detection signal DS 1 , and detect a second pulse PS 2  of the detection signal DS 1  in a time interval TD M+1 . Then, the command voltage generator  130  may calculate time required between the pulse PS 1  and the pulse PS 2  to obtain a time T K−1 . Then, the command voltage generator  130  continuously detects the detection signal DS 1 , and detect a third pulse PS 3  of the detection signal DS 1  in a time interval TD N . The command voltage generator  130  thus calculates time between the pulse PS 2  and the pulse PS 3  to obtain a time T K . 
     After obtaining the times T K−2 , T K−1 , and T K , the command voltage generator  130  may perform the numerical value derivation operation based on the times T K−2 , T K−1 , and T K  to generate the estimated velocity value accordingly. In an embodiment of the invention, the command voltage generator  130  may calculate an estimated velocity value VE based on the times T K−2 , T K−1 , and T K  and reciprocals (inverse elements of multiplication) of the times T K−2 , T K−1 , and T K . The calculation may be represented in Formula (1) below: 
     
       
         
           
             
               
                 
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     The command voltage generator  130  may continuously detect the detection signal DS. In addition, under a condition that new pulses are continuously generated in the detection signal DS, the command voltage generator  130  may perform the numerical value derivation operation based on the latest three sequential times to generate the latest estimated velocity value VE. 
     Besides, generating the estimated velocity value by performing the numerical value derivation operation based on the three times T K−2 , T K−1 , and T K  is merely described as an example. The numerical value derivation operation in the embodiments of the invention may be performed based on a greater number of times. 
     In the following, details about the electricity aid strategy table are described. The electricity aid strategy table may be set in a memory apparatus, and the memory apparatus may be built in or externally connected to the command voltage generator  130 . In an embodiment, the electricity aid strategy table may be in the form of a lookup table and record the relation between the electricity aid ratio and the estimated velocity value VE. The electricity aid strategy table indicates the amount of auxiliary power that the auxiliary motor MOT is required to generate. When the electricity aid ratio is higher, the auxiliary motor MOT is required to generate more auxiliary power. When the electricity aid ratio is lower, the auxiliary motor MOT is required to generate less auxiliary power. In the electricity aid strategy table, the electricity aid ratio is negatively proportional to the estimated velocity value VE. 
     Referring to  FIG. 3 ,  FIG. 3  is a schematic view illustrating a command voltage generator according to an embodiment of the invention. A command voltage generator  300  includes a processor  310  and a lookup table  320 . The processor  310  receives the detection signal DS and is coupled to the lookup table  320 . The electricity aid strategy table is recorded in the lookup table  320 . The processor  310  detects a pulse generation state in the detection signal DS and obtains a plurality of times between adjacent pulses. Then, the numerical value derivation operation is then performed continuously based on the times, so as to generate the estimated velocity value VE. Based on the estimated velocity value VE, the processor  310  performs a lookup operation in the lookup table  320  and obtains the electricity aid ratio corresponding to the estimated velocity value VE. The processor  310  also generates the command voltage V* based on the electricity aid ratio. 
     Referring to  FIG. 4 ,  FIG. 4  is a schematic view illustrating a command voltage generator according to another embodiment of the invention. A command voltage generator  400  includes a filter  410 , format converters  420  and  450 , a lookup table  430 , and a processor  440 . The filter  410  receives the detection signal DS and filters out noises of the detection signal DS. The filtered detection signal DS is transmitted to the format converter  420  for signal format conversion. In the embodiment, the format converter  420  is an analog-to-digital converter. 
     The processor  440  receives a detection signal in a digital format, and generates the command voltage based on the electricity aid strategy table in the lookup table  430 . The format converter  450  converts the signal format of the command voltage generated by the processor  440  to generate the command voltage V* in an analog format. In the embodiment, the format converter  450  is a digital-to-analog converter. 
     In the embodiments shown in  FIGS. 3 and 4 , the processors  310  and  440  may be processors having a computing capability. Alternatively, the processors  310  and  440  may be hardware circuits designed based on the hardware description language (HDL) or any other digital circuit design methods that people having ordinary skill in the art are familiar with and implemented in the form of field programmable gate array (FPGA), complex programmable logic device (CPLD), or application-specific integrated circuit (ASIC). 
     The lookup tables  320  and  430  may be implemented in any memory apparatuses that people having ordinary skills in the art are familiar with, such as memories in an arbitrary form. The filter  410  may be implemented as a filter circuit that people having ordinary skills in the art are familiar with. Also, the format converters  420  and  450  may be implemented as any analog-to-digital converter circuits and digital-to-analog converter circuits that people having ordinary skills in the art are familiar with. In other words, the invention does not intend to impose a specific limitation on this regard. 
     Referring to  FIG. 5 ,  FIG. 5  is a schematic view illustrating a command voltage generator according to yet another embodiment of the invention. In  FIG. 5 , the command voltage generator  500  may be implemented on a circuit board  510  as a modularized apparatus (e.g., a command voltage generator module  501 ). A connector  520  is disposed on the circuit board  510 . Moreover, the circuit board  510  may be detachably connected to the corresponding electricity aided bicycle through the connector  520 . When at least one of the velocity estimation method or the electricity aid strategy of the electricity aided bicycle requires modification, such modification may be carried out by simply replacing the command voltage generator module  510 . Hence, the manufacture and assembling of the electricity aided bicycle is facilitated. 
     The connector  520  may be a connector in an arbitrary form. The goldfinger-type connector shown in  FIG. 5  merely serves as an example and is not intended to serve to limit the invention. Moreover, other circuit devices may also be disposed on the circuit board  510 . The invention does not intend to impose a specific limitation on this regard. 
     Referring to  FIG. 6 ,  FIG. 6  is a schematic view illustrating an electricity aid strategy according to an embodiment of the invention. In an embodiment of the invention, during setting of the electricity aid strategy, a plurality of reference velocities VR 1  to VR 3  and a plurality of corresponding electricity aid ratios R 1  to R 2  may be set. In an example where the reference velocity VR 1  is less than the reference velocity VR 2 , the reference velocity VR 2  is less than the reference velocity VR 3 , and the electricity aid ratio R 2  is greater than the electricity aid ratio R 1 , when the estimated velocity value is less than the reference velocity value VR 1 , the electricity aid strategy correspondingly provides the relatively greater electricity aid ratio R 2 , and when the estimated velocity value is between the reference velocity values VR 1  and VR 2 , the electricity aid strategy correspondingly provides the relatively lower electricity aid ratio R 1 . When the estimated velocity value is greater than the reference velocity value VR 2 , the corresponding electricity aid ratio in the electricity aid strategy is 0. 
     Referring to  FIG. 7 ,  FIG. 7  is a schematic view illustrating an electricity aided bicycle according to another embodiment of the invention. An electricity aided bicycle  700  includes a command voltage generator  710 , a driving circuit  720 , a voltage detector  730 , a filter  740 , a Hall detector  750 , a rotating speed detector  760 , and operators OP 1  to OP 3 . The command voltage generator  710  generates a command voltage V* and provides the command voltage V* to the driving circuit  720 . The driving circuit  720  includes a multiple phase command voltage generator  721  and a driving signal generator  722 . The multiple phase command voltage generator  721  generates multiple phase command voltages V a *, V b *, and V c * based on the command voltage V*, and provides the multiple phase command voltages V a *, V b *, and V c * to the operators OP 1  to OP 3 . The operators OP 1  to OP 3  respectively perform subtract operations between the multiple phase command voltages V a *, V b *, and V c * and a plurality of feedback signals, and transmit generated operation results to the driving signal generator  722 . 
     The driving signal generator  722  is configured to generate a plurality of driving signals Q 1  to Q 6  and drives a transistor Tx through the driving signals Q 1  to Q 6 , thereby providing a driving voltage to the auxiliary motor MOT. 
     Moreover, the voltage detector  730  is coupled to the auxiliary motor MOT, detects a plurality of driving phase voltages V a , V b , and V c  of the auxiliary motor MOT, and generates the feedback signals. The feedback signals are filtered at the filter  740  to filter out noises, and are provided to the operators OP 1  to OP 3  for the subtract operations. 
     Besides, the Hall detector  750  detects a rotation status θ e  of the auxiliary motor MOT, and transmits the detected rotation status θ e  to the multiple phase command voltage generator  721  as the basis for the multiple phase command voltage generator  721  to generate the multiple phase command voltages V a *, V b *, and V c *. 
     The rotating speed detector  760  detects the rotation status of the driving gear of the electricity aided bicycle  700  and generates the detection signal DS. 
     Referring to  FIG. 8 ,  FIG. 8  is a flowchart illustrating an auxiliary power controlling method of an electricity aided bicycle according to an embodiment of the invention. At Step S 810 , a detection signal having a plurality of pulses is generated based on a rotation status of a driving gear of the electricity aided bicycle. At Step S 820 , a plurality of times between two adjacent pulses in the pulses of the detection signal is calculated. At Step S 830 , a numerical value derivation operation is performed on the times to generate an estimated velocity value. Then, at Step S 840 , an electricity aid strategy table is set, and a command voltage is calculated based on the estimated velocity value and the electricity aid strategy table. 
     Details concerning the respective steps are already described in detail in the above embodiments and thus will not be repeated in the following. 
     In view of the foregoing, in the embodiments of the invention, the rotation status of the driving gear is detected to generate the detection signal having the pulses. In addition, the numerical value derivation operation is performed based on the times between the pulses of the detection signal, so as to generate a stable estimated velocity value. In addition, the electricity aid strategy table is set in the embodiments of the invention to provide the electricity aid ratio. Hence, the auxiliary motor is able to provide an appropriate auxiliary power more effectively, and the convenience of use and the safety of the electricity aided bicycle are facilitated. 
     It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.