AU671791B1 - Motor-driven vehicle - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Applicant: NABCO LIMITED Invention Title: MOTOR-DRIVEN VEHICLE The following statement is a full description of this invention, including the best method of perf orming it known& to me/us: 4* 4 44 49 4444 4 .4 .9 4 4 44 44 4 4 44 4 *44~ 4 49 44 9 944 4 444* 4 49 499444 4 4 9 L L I-I I Ir I L MOTOR-DRIVEN VEHICLE The present invention relates to a motor-driven vehicle, such as a motor-driven wheelchair.

BACKGROUND OF THE INVENTION An example of prior art motor-driven wheelchairs is shown in FIGURE 1. A wheelchair 2 includes a chair body 4 which is formed by a pipe framework. The body 4 includes handlebars 8 with handlegrips 6, a back 10, a seat 12, armrests 14, and footrests 16.

The chair body 4 is provided with a pair of drive wheels 18 and a pair of follower wheels 20. For each of the drive wheels 18, a motor 20 is used which is coupled through a gear transmission (not shown) to the drive wheel 18. The motors 20 may be geared DC motors. A clutch is provided in association with each motor 20 or each gear transmission, and, when the clutch is operated, the associated drive wheel 18 can be freely rotatable. With the respective clutches operated, an attendant or helper, gripping the 20 handgrips 6, can push or pull the chair body to mrove the wheelchair forward or backward by human power.

A control unit 22 is also provided on the chair body 4. The control unit 22 includes a joystick 24 for use in steering the wheelchair 2. The control unit 22 controls the respective motors 25 20 to move the wheelchair 2 in the direction corresponding to the direction in which the joystick 24 is tilted. A battery 26 is also mounted on the chair body 4 for supplying power to the motors and the control unit 22. The battery 26 may be, for example, an automobile chargeable lead-acid battery.

!1 -r I I t, I I The motor-driven wheelchair 2 is either motor-driven by means of the motors 20 or driven by human power. In the latter case, the clutches are decoupled from the motors.

The motor-driven wheelchair 2 can be used by a person handicapped or weak not only in the lower half of their body, but also in the upper half of the body.

As previously stated, the motor-driven wheelchair 2 shown in FIGURE 1 is either driven by the motors 20 or by an attendant. In the latter case, the clutches are decoupled from the motors However, when a user or handicapped sits on the seat, the sum of the weights of the user and the wheelchair may be a hundred and several tens kilograms and, therefore, an attendant can move the wheelchair i, ith a person sitting only on a horizontal, flat surface.

Accordingly, even when a helper is attending, the motors 20 are very often used to drive the wheelchair 2, and, therefore, the battery power is consumed rapidly, which requires the battery 26 to be frequently charged.

An object of the present invention is to provide a motor-driven vehicle, such as a motor-driven wheelchair, which can be operated S with ease by human power and in which power consumed by motors for driving the vehicle can be reduced by taking advantage of human power given by a person to drive the vehicle, with no increase in burden placed on the person who drives the vehicle.

o 25 SUMMARY OF THE INVENTION 0 According to an aspect of the present invention, a motor-driven vehicle includes a vehicle body having a handlebar, a drive wheel, electrical driving means for driving the drive wheel selectively in forward and reverse directions to thereby move the vehicle body, and manual-driving-force sensing means for sensing a manual-driving- 0 force applied to the handlebar and selectively generating forward and reverse control signals for controlling the driving means. The manual-driving-force sensing means includes a displaceable grip mounted on the end of the handlebar, which grip is displaceable back and forth along the length of the handlebar. The sensing means further includes displacement sensing means for sensing displacement of the displaceable grip and selectively generating the forward control and reverse control signals in accordance with the displacement of the grip, and elastic means disposed within the grip for transmitting force exerted to the displaceable grip to the handlebar. The elastic means transmits to the handlebar, force exerted in the direction toward the handlebar or in the direction opposite thereto.

The manual-driving-force sensing means includes two stop members disposed spaced on and along the length of the displaceable grip. The two stop members are coupled to the handlebar and contacted by respective ones of the two ends of the elastic means.

The sensing means further includes first releasing means for releasing one end of the elastic means from its contact with an 20 associated one of the stop members in response to the displacement of the grip toward the handle and compressing said elastic means in the direction toward the handlebar, and also includes second releasing means for releasing the other end of the elastic means from its contact with the other of the stop members in response to 25 the displacement of the grip in the opposite direction and compressing the elastic means in the opposite direction.

According to another aspect of the invention, a motor-driven vehicle includes a vehicle body having a handlebar, a drive wheel, electrical driving means for driving the drive wheel, and manualdriving-force sensing means for sensing a manual-dr i ving-force applied to the handlebar and generating a control signal for controlling the driving means. The manual-driving-force sensing means includes a displaceable grip displaceable back and forth along the length of the handlebar, displacement sensing means for sensing the displacement of the grip and generating the control signal, and also elastic means disposed along the length direction of the handlebar within the displaceable grip. The elastic means is compressed when force is exerted to the grip, when it is in a neutral position thereof, in the direction toward the handlebar or in the opposite direction, and returns to its neutral position when the force exerted to the grip is removed.

The manual-driving force sensing means includes two stop members disposed spaced within and along the length of the displaceable grip and contacted by respective ones of the two ends of the elastic means. The sensing means further includes first and second actuating members. The first actuating member is responsive to the displacement of the grip toward the handlebar for disengaging the end of the elastic means remote from the handlebar from one of a A the two stop members and compresses the elastic means in the 20 direction toward the handlebar. The second actuating member is responsive to the displacement of the grip in the direction away from the handlebar for disengaging the end of the elastic means closer to the handlebar from the other one of the two stop members and compressing the elastic means in the direction away from the S 25 handlebar.

The elastic means is pre-compressed in such a manner that the two ends of the elastic means are in contact with respective ones of the two stop members when the displaceable grip is not displaced in either directions.

A motor-driven vehicle may be provided with a drive wheel on I I s i r- each of the two opposing sides with electrical driving means provided for each of the drive wheels. The vehicle also includes two handlebars for the respective drive wheels, and manual-drivingforce sensing means is provided for each of the handlebars to thereby generate a control signal for a respective one of the drive wheels.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a perspective view of a prior art motor-driven wheelchair; FIGURE 2 is a perspective view of a motor-driven wheelchair K according to a first embodiment of the present invention; FIGURE 3 is a representation in a block diagram of the motordriven wheelchair shown in FIGURE 2; FIGURE 4 is a right side view of a right-side drive wheel of the motor-driven wheelchair shown in FIGURE 2; FIGURE 5 is a cross-sectional view along a line V-V in FIGURE 4; FIGURE 6 is a left side view of the right-side drive wheel shown in FIGURE 4; FIGURE 7 is a diagram showing the relationship in position between light-emitting diodes and phototransistors used in the motor-driven wheelchair of FIGURE 2; FIGURE 8 shows waveforms of currents in the phototransistors 25 receiving light, and a combined current in the arrangement shown in FIGURE 7; *FIGURE 9 is a longitudinal cross-sectional view of a manualdriving-force sensing unit in its neutral position of the motordriven wheelchair of FIGURE 2, FIGURE 9a is a similar crosssectional view of the manual-driving-force sensing unit of FIGURE 9 L- LL~ I L d I II Tit ~-rSL~illrY when a grip of the wheelchair is pulled, and FIGURE 9b is a similar cross-sectional view of the manual-driving-force sensing unit when the grip is pushed; FIGURE 10 is a diagram showing the relationship between manual driving force applied to the manual-driving-force sensing unit and the displacement of the manual-driving-force sensing unit; FIGURE 11a shows a relationship between manual driving force exerted to the wheelchair of FIGURE 2 and a motor-torque related signal from which a signal to be applied to a motor driving the drive wheel is prepared; FIGURE lib shows a relationship between manual driving force exerted to the wheelchair of FIGURE 2 and acceleration of the wheelchair; FIGURE 12a shows an example of change in velocity of the motordriven wheelchair with time; FIGURE 12b shows an example of change in manual driving force exerted to the motor-driven wheel chair with time; and FIGURE 13 is a flow chart showing the arithmetic processing by a CPU in a signal converting unit of the wheelchair shown in FIGURE 20 3.

o. DETAILED DESCRIPTION OF EMBODIMENTS 5 FIGURE 2 shows a motor-driven vehicle, for example, a motordriven wheelchair 30 according to a first embodiment of the present :.oo 25 invention. The wheelchair 30 includes a chair body 32 built by a pipe framework, for example. The chair body 32 is provided with a V0 a• iback 34, a seat 36, armrests 38, and footrests 40. Handlebars 42R and 42L extend rearward from the right and left sides of the rear of the pipe framework. (Throughout the specification, letters "R" and represent "right" and "left" respectively. Thus, the 6 I 7 handlebar 42R, for example, is the one on the right side of the wheelchair 30.) A pair of right and left follower wheels 44K and 44L are rotatably mounted on the pipe framework on its right and left sides of the front lower portion. In the rear portion of the pipe framework, a pair of right and left drive wheels 46R and 46L are mounted on the right and left sides of the pipe framework. The diameter of the drive wheels 46R and 46L are larger than that of follower wheels 44R and 44L. Outside the respective drive wheels 46R and 46L, annular hand rims 48R and 48L made of pipes are secured via spacers 200R and 200L to the drive wheels. The diameter of the hand rims 48R and 48L is slightly smaller than that of the drive wheels 46R and 46L.

As will be explained later in detail with reference to FIGURE 3, within the respective drive wheels 46R and 46L, there are disposed motors 76R and 76L for selectively driving the drive wheels 46R and 46L in a forward direction to drive the wheelchair forward, for example, and in a reverse direction to drive the wheelchair .0 backward, as well as signal receiver (RX) units 86R and 86L, control (CONT) units 88R and 88L, and driving (DR) units 90R and 20 90L, which are used to control the motors 76R and 76L, respectively, and also batteries 82R and 82L for feeding power to the motors and respective units.

A pair of manual-driving-force sensing units 50R and 50L are provided on the handlebars 42R and 42L. The manual-driving-force sensing unit 50R senses a manual driving force exerted to it and develops an analog electrical signal fiR representative of the magnitude and direction of the exerted manual driving force. The unit 50R also acts to transmit the exerted manual driving force to the handlebar 42R. Similarly, the manual-driving-force sensing unit 50L senses a manual driving force exerted to it and develops I 1 I I-I I 1 an analog electrical signal fIL representative of the magnitude and direction of the exerted manual driving force. The unit transmits the exerted manual driving force to the handlebar 42L.

Indicator lamps 52R and 52L indicating that the wheelchair 30 is moving forward, and indicator lamps 54R and 54L indicating that the wheelchair 30 is moving backward may be mounted on the respective handlebars 42R and 42L.

Beneath the seat 36 of the chair body 32, there is provided a signal converting unit 56 which converts signals from the manualdriving-force sensing units 50R and 50L into motor control signals.

As shown in FIGURE 3, the signal converting unit 56 includes an analog-to-digital converter 92 which converts the analog electrical signal flR and fIL into digital electrical signals DflR and DfiL, respectively. The digital signals Df1R and DfIL are applied to a central processor unit (CPU) 94 where they are converted into digital driving signals or digital motor-torque related signals Df2R and Df2L for the respective motors 76R and 76L. The digital motor-torque related signals Df2R and Df2L are amplified by an amplifier 36. The digital motor-torque related signal Df2R is applied to a transmitter (TX) unit 98R for the drive wheel 46R, and the digital motor-torque related signal Df2L is applied to a transmitter (TX) unit 98L for the drive wheel 46L.

The transmitter units 98R and 98L may be light-transmitter which include light-emitting elements, such as, infra-red light emitting 25 diodes, and transmit light signals, such as infrared signals, to receiver units 86R and 86L, respectively.

The receiver units 86R and 86L may be light-receivers including E light-receiving elements, such as phototransistors, which receive and demodulate light-signals transmitted by the associated I transmitters 98R and 98L and produce the digital motor-torque

I

I II i ii I related signals Df2R and Df2L. The digital motor-torque related signals Df2R and Df2L are applied to the control units 88R and 88L, respectively. The control units 88R and 88L may modulate the pulse widths of voltages which are applied to the motors 76R and 76L, respectively, with the torque-related signals Df2R and Df2L, and apply the pulse-width modulated voltage signals to the driving units and 90L, to thereby vary the values of current to be applied to the motors 76R and 76L so that the torques of the motors 76R and 76L vary. Thus, the driving units 90R and 90L and the control units 88R and 88L form control means. The drive wheels 46R and 46L are independently controlled in accordance with the manual driving forces sensed by the associated manual-driving-force sensing units and 50L, respectively.

As shown in FIGURES 5 and 6, the right-side drive wheel 46R includes an axle 58R secured to the chair body 32. A rotating section 62R is rotatably mounted on the axle 58R with a bearing interposed therebetween. The rotating section 62R includes a hub 64R with the bearing 60R in it, and a plurality of spokes 66R extend radially from the hub 64R and connect at their distal ends to a 20 substantially annular rim 68R. A tire 70R is mounted around the rim 68R.

As shown in FIGURE 5, a gear 72R is fixed coaxial with the axle 58R. Two reinforcement panels 74R1 and 74R2 are disposed within diametrically opposing spaces each defined by two adjacent spokes oo: 25 66R and are secured by clamps 73R to the wheels, and two motors 76R1 and 76R2 are secured by screws 75R to the respective reinforcement i t panels 74R1 and 74R2, as shown in FIGURE 4. More than two motors i may be used, and, in such a case, the motors are disposed on a circle concentric with the axle 58R at angularly equally separated locations. For example, if three motors are used, they are spaced by 120 degrees from each other.

Two pinions 80R1 and 80R2 are coaxially secured to the output shafts 78R1 and 78R2 of the motors 76R1 and 76R2. The pinions 80R1 and 80R2 are in mesh with the gear 72R. As the motors 76R1 and 76R2 are energized to rotate, the pinions 80R1 and 80R2 roll along the periphery of the gear 72R, which results in rotation of the rotating section 62R. The motors 76R1, 76R2, the gear 72R, and the pinions 80R1, 80R2 form electric driving means.

Two batteries 82R1 and 82R2 are mounted by merl' support members 84R1 and 84R2 fitted and secured within spaces each defined by two adjacent spokes 66R. The batteries are disposed on a circle concentric with the axle 58R with the same angular spacing from each other as the angular spacing between the motors. In the illustrated embodiment, the angular spacing is 180 degrees. The battery 82R1 is spaced by 60 degrees from the associated motor 76R1 and by 120 degrees from the other motor 76R2, while the battery 82R2 is spaced from the associated motor 76R2 by 60 degrees, and by 120 degrees from the motor 76R1.

The control unit 88R and the driving unit 90R are disposed within respective spaces each defined by two adjacent spokes 66R.

The angular spacing between the locations where the control unit 88R and the driving unit 90R are disposed is equal to the angular S spacing between the motors 76R1 and 76R2, i.e. 180 degrees in the illustrated case. The spaces where the control unit 88R and the driving unit 90R are disposed are different from those where the motors and batteries are respectively disposed. The control unit 88R and the driving unit 90R may be disposed on plates which, in turn, are fitted within the respective spaces and secured to the respective spokes by means of, for example, clamps (not shown) like the clamps 73R.

i n Ii By arranging the motors 76R1 and 76R2, the batteries 82R1 and 82R2, the control unit 88R, and the driving unit 90R as described above, the drive wheel 46R is balanced. It is noted that the motors 76R1, 76R2, the batteries 82R1, 82R2, the control unit 88R, and the driving unit 90R are positioned substantially in the same single plane within the rotating section 62R which is perpendicular to the axis of the axle 58R, which also facilitates the balancing of the drive wheel 46R.

As shown in FIGURE 5, an outer cover 100R and an inner cover 102R are fixed to the rim 68R so as to enclose the motors 76R1 and 76R2, the gear 72R, the pinions 78R1 and 78R2, etc. therein.

The other, left-side drive wheel 46L is similarly constructed.

Similar components are shown with the same reference numerals with a letter attached at the end instead of and their descriptions are not made.

As shown in FIGURES 5 and 6, the inner cover 102R has a circular opening 104R in its center which is concentric with the axle 58R. Plural, for example, eight, light-receiving elements, such as phototransistors, T1R-T8R which constitute the receiver unit 86R are equidistantly disposed along the periphery of the opening 104R. The phototransistors T1R-T8R are electrically connected in parallel.

Plural, for example, two, light-emitting elements, such alight-emitting diodes, DIR and D2R which constitute the transmitter 25 unit 98R are disposed at predetermined locations which radially outward of the opening 104R. The light-emitting diodes DIR and D2R Sare fixed to a framework pipe of the chair body 32 by means of a mounting member 106R. The light-emitting diodes D1R and D2R are also electrically connected in parallel with each other. The S 30 phototransistors T1R-T8R rotate with the drive wheel 46R and, while h1 1 they are rotating, receive infrared signals from the light-emitting I diodes D1R and D2R.

As shown in FIGURE 7, the spacing P2 between adjacent ones of the phototransistors T1R-T8R is determined such that at any time, one or more of the phototransistors T1R-T8R is present within their detectable range R which, in turn, is determined by the infrared isignal radiation angle 0 1 of the light-emitting diodes D1R and D2R, and the detectable light receiving angle 0 2, the orbit and the sensitivity of the phototransistors TIR-T8R. More specifically, in the illustrated embodiment, it is desirable that the spacing P2 between adjacent ones of the phototransistors T1R-T8R and the spacing P1 between the two light-emitting diodes D1R and D2R be set to be such that P2/P1 1.5-0.5, for example.

In FIGURE 7, when the drive wheel 46R rotates in the direction indicate by an arrow, current I flowing in the receiver unit 86R in response to light received is the combination of currents 11-18 generated in the respective ones of the phototransistors T1R-T8R in response to light received by the respective phototransistors, as shown in FIGURE 8. Thus, although more or less pulsating, the current I always flows. The smaller the ratio P2/P1, the pulsation of the current I is smaller, which is desirable. However, it may S. be compromised with the cost.

I The structures of the receiver unit 86L and the transmitter unit 98L are substantially the same as those of the receiver unit 86R and the transmitter unit 98R, and, therefore, no detailed explanation about them is made.

A manually driven wheelchair may be easily modified into the motor-driven wheelchair 30 by attaching the manual-driving-force sensing units 50R and 50L, the converting unit 56, and the transmitter units 98R and 98L on the wheelchair body 32, and 1 9 1.

mounting the motors 76R and 76L, the receiver units 86R and 86L, t the control units 88R and 88L, the driving units 90R and 90L, and the batteries 82R and 88L within the respective drive wheels 46R and 46L. In this case, the larger the drive wheels 46R and 46L used, the larger space is available for the batteries so that larger capacity batteries can be used.

Each of the manual-driving-force sensing units 50R and senses the magnitude and direction of force exerted to it, and the drive wheels 46R and 46L are driven in accordance with the sensed force, as described above.

One of the manual-driving-force sensing units, namely, the manual-driving-force sensing units 50L is now described in detail with reference to FIGURES 9 and FIGURES 9a and 9b. Although the details and operation of the other manual-driving-force sensing i unit 50R are not shown or described, they are substantially the same as those of the sensing unit The manual-driving-force sensing unit 50L in its neutral position where no force is exerted to it, is shown in FIGURE 9. The sensing unit 50L includes a cylindrical fixed portion 106L which i 20 has its one end inserted into the handlebar 42L formed of a pipe.

iI The portion 106L is fixed to the handlebar 42L by means of screws S, 108L. A cylindrical member l10L having a chamber in which an elastic member 136, such as a spring described later in detail, is housed is threaded at its one end and is screwed over and joined to I 25 the other end of the fixed portion 106L. A grip 112L extending along the length of the fixed portion 106L houses the fixed portion 106L and the spring casing 110L. The grip 112L is displaceable along the length of the fixed portion by virtue of rolling steel balls 113L. The other end or end remote from the handlebar 42L of the grip 112L is provided with a lid 114L which closes the open end I n C C~ of the grip 112L. A stop 116L is formed in the interior of the grip 112L to engage with a recess 118L which is formed in the surface of the fixed portion 106L to extend along the length of the portion 106L. Thus, the grip 112L can be displaced along the length direction of the handlebar 42L within the range equal to the length of the recess 118L.

Displacement sensing means, such as a potentiometer, 120L is disposed within the fixed portion 106L. A fixing ring 124L which is screwed into a poriton 122L having a thread formed in the inside surface of the fixed portion 106L fixes the potentiometer 120L with respect to the fixed portion 106L. A columnar member 123L protrudes from the center of the inner surface of the lid 114 toward the potentiometer 120L. A piston 126L having a diameter smaller than that of the columnar member 123L extends from the member 123L toward the potentiometer 120L along the length of the spring casing 110.

The piston 126L is fixed to the lid 114L by means of a screw 128L.

i As shown in FIGURE 9a, elastic member driving means, such as a step or shoulder 127L is formed in the columnar member 123L at a portion where the piston 126L is joined to the columnar member U 20 123L. The distal end of the piston 126L is formed to have a larger diameter and is provided with elastic member driving means, such as I* t a step or shoulder 129L. As shown in FIGURE 9, the enlaiged distal end of the piston 126L is coupled by a connecting wire 132L and an attachment 134L to a sensing element 130L. Thus, when the grip 112L is displaced to and fro, the piston 126L and, hence, the sensing element 130L, are also displaced, accordingly.

Within the chamber of the spring casing 110L, disposed is an elastic member, such as a spring, 136L. The two ends of the spring 136L are in contact with respective spring holder rings 138L and 140L which are mounted on the piston 126L in such a manner as to be I I FI I~ 1I slidable on the piston 126L. Stops, such as steps, 142L and 144L are provided at opposite ends of the chamber of the spring casing 11OL, so that the spring holder rings 138L and 140L can be contacted with them. The rings 138L and 140L can contact also with the shoulders 127L and 129L of the piston 126L. When the grip 112L is not displaced, i.e. when the grip 112L is in its neutral position, as shown in FIGURE 10, the ring 138L is in contact with the step 142L at the end of the chamber closer to the lid 114L as well as the shoulder 127L of the 'Y:ston 126L, while the ring 140L is in contact with the shoulder 144L of the fixed portion 106L as well as the step 129L of the piston 126L. The distance between the steps 142L and 144L is equal to the distance between the shoulders 127L and 129L, so that the grip 112L is restricted in a predetermined neutral position (shown in FIGURE 9) by the repulsion of the spring 136L, in which position the grip 112L is not actuated and the rings 138L and 140L are in contact with the steps 142L and I: 144L, respectively. In order to retain the grip 112L in this predetermined position, it is desirable that the spring 136L be prei compressed when it is disposed within the chamber of the spring casing llOL.

When manual driving force F1L is exerted to the grip 112L in the neutral position in such a direction that it is displaced toward handlebar 42L of the wheelchair as shown in FIGURE 9b, the spring holder ring 140L does not move since it is in contact with the step 14qL of the spring casing llOL. On the other hand, the spring "holder ring 138L is pushed toward the handlebar 42L by the shoulder 127L of the piston 126L so that the end of the spring 136L is released from its contact with the step 142L, which, in turn, causes the spring 136L to be compressed and, at the same time, causes the piston 126L to push the sensing element 130L toward the handlebar 1 t 42L. At the same time, because the spring 136L has been compressed, its compression force is transmitted via the fixed portion 106L to the handlebar 42L.

When manual driving force FIL is exerted in the opposite direction so that the grip 112L is displaced away from the handlebar 42L as shown in FIGURE 9a, the spring holder ring 138L does not move since it is in contact with the step 142L of the spring casing However, since the ring 140L is in contact with the shoulder 129L of the piston 126L, the piston 126L releases the end of the spring 136L from the contact with the step 144L and is pushed away from the handlebar 42L so that the spring 136L is compressed and the sensing element 130L is pulled out. At the same time, because the spring 136L has been compressed, the compression force is transmitted to the handlebar 42L through the spring casing l10L and the fixed portion 106L.

The manual driving force FIL acting in either direction, i.e.

in the direction toward the handlebar or in the opposite direction, is removed, the repulsion of the single spring 136L brings the grip 112L to its original, predetermined neutral position.

As stated above, depending on the direction of the manual driving force FIL exerted to the grip 112L, the direction of displacement of the sensing element 130L is determined, and the amount of displacement of the sensing element 130L is in proportion to the magnitude of the manual driving force FIL.

A manual-driving-force sensing circuit, such as a Wheatstone S° bridge circuit, in the manual-driving-force sensing unit 50L (FIGURE 3) including the potentiometer 120L senses the direction and magnitude of the manual driving force FIL and develops an analog electrical signal fIL. As shown in FIGURE 10, the analog signal fiL represents the direction, e.g. a forward direction toward the 1 6 i-ir handlebar or a reverse direction away from the handlebar, and magnitude of the force applied to the grip 112L.

In FIGURE 10, a reference numeral 146 denotes a dead zone which is present due to the pre-compression of the spring 136L. Only when the manual driving force FIL exceeds values a and b defining the limits of the dead zone 146, an analog signal fIL is generated.

The width of the dead zone 146 can be adjusted by adjusting the degree of the pre-compression of the spring 136L.

In FIGURE 10, a symbol indicates that the manual driving force FIL is in the direction to push in the grip 112L or to displace it toward the handlebar 42L, ihcretas a symbol indicates that the force FIL is exerted in the direction to pull out the grip 112L or to displace it away from the handlebar 42L.

Although not shown, a similar manual-driving-force sensing arrangement 50R is provided for the right-hand handlebar 42R, and the manual-driving-force sensing unit 50R develops a similar analog electrical signal fiR representing the direction and magnitude of an 1 exerted force F1R.

The signals flR and flL are converted into digital signal DflR and DfIL in the A/D converter 92 in the signal converting unit 56, and, then, converted in the CPU 94 into motor-torque related signal Df2R and Df2L, respectively. The digital motor-torque related signals Df2R and Df2L are applied to the transmitter units 98R and 98L, respectively, for transmission to the receiver units 86R and 86L, as described previously.

:a The relationship between the digital motor-torque related signal Df2R and the manual driving force F1R which is represented by the digital signal DflR which, in turn, is proportional to the manual driving force FIR, is shown in FIGURE lla, and the relationship between the digital signal DfIR and the acceleration i O X I of the motor-driven wheelchair 30 is shown in FIGURE lib.

As will be understood from FIGURE lla, when the manual driving force FIR is within the dead zone 146 in FIGURE 10 and, therefore, the digital signal DflR is within a dead zone, shown in FIGURE Ila, which corresponds to the dead zone 146, and which is defined by values a' and b' that correspond to the values a and b of the manual driving force FIR shown in FIGURE 10, the digital motortorque related signal Df2R remains 0. As the manual driving force FIR increases so that the digital signal DfIR increases beyond the value the digital motor-torque related signal Df2R is expressed as K DfIR- a and is proportional to the digital signal DfIR and, hence, to the manual driving force FIR. When the manual driving force FIR is smaller so that the digital signal DflR is less than the value the digital motor-torque related signal Df2R is expressed as K. DflR+ 3 and is proportional to the digital signal DflR and, hence, to the manual driving force FIR. In the two expressions, K is a coefficient, and a, and are constants.

When, for example, the digital signal DfIR is at a point C in FIGURE lla, that is, when no manual driving force FIR is exerted, the motor-torque related digital signal Df2R is also zero, and, therefore, as shown in FIGURE llb, the acceleration is also zero.

When the digital signal DflR is at a point B which is within the dead zone, the motor-torque related signal Df2R remains zero, but the acceleration increases by an amount corresponding to the manual driving force FIR exerted to the wheelchair by an attendant.

t At a point A, the digital signal DflR is greater than the value a', which means that a manual driving force FIR which exceeds the value a shown in FIGURE 10 is exerted, acceleration is generated by the motor 76R, and the sum of the acceleration produced by the manual driving force FIR exerted by the attendant and the acceleration 18 produced by the motor 76R is given to the wheelchair 30. The points A and B are exemplified to explain cases in which the attendant accelerates the wheelchair.

On the other hand, the digital signals DfIR at points 1) and E correspond to manual driving forces FIR which are exerted to the wheelchair by the attendant to decelerate the wheelchair. The motor-torque related digital signal Df2R and the acceleration exhibit point-symmetry with the point C being a point of symmetry.

At the points A and E, the wheelchair 30 is accelerated by both the manual driving force FIR given by the attendant and the driving force given by the motor 76R, with the motor-torque varying in accordance with the magnitude of the manual driving force FIR.

Thus, the wheelchair 30 is driven by the collaboration of the attendant and the motor 76R.

Also, it is arranged that the same relationship exists between the digital signal DfiL or the manual driving force F1L and the motor-torque related signal Df2L. Thus, the acceleration produced by the motor 76R is controlled in accordance with the manual driving force FIR as sensed by the manual-driving-force sensing unit 50R, and the acceleration produced by the motor 76L is controlled in accordance with the manual driving force F1L as sensed by the manual-driving-force sensing unit FIGURES lla and lib show the motor-torque related signal and the acceleration when the wheelchair 30 is driven on a horizontal, flat path. When the wheelchair 30 is driven to ascend or descend a S"oleo slope, the accelerations provided by the motors 76R and 76L change depending on the magnitudes of the manual driving forces FIR and FiL which are exerted in the direction opposing the gravitational acceleration.

The dead zone is for preventing unstable movement of the I C 1 wheelchair 30 which could be caused if the motors 76R and 76L respond to small manual driving forces FIR and FIL.

The coefficient K, the constants a and 3, the limit values a and b of the dead zone 146 or the values a' and b' of the dead zone of the digital signal DfIR, DflL are so set that desired accelerations can be provided in accordance with the manual driving force FIR, FiL.

Since the motors 76R and 76L are driven in accordance with the manual driving forces FIR and FIL provided by an attendant, as described above, the wheelchair 30 can be driven as driving a manually driven wheelchair. This is described further with reference to FIGURES 12a and 12b.

FIGURE 12a shows variations with time in velocity of the wheelchair 30, and FIGURE 12b shows the manual driving forces FIR and FiL exerted to the manual-driving-force sensing units 50R and which cause the variations in velocity of the wheelchair shown in FIGURE lla, assuming that the manual driving forces FIR and F1L are equal to each other. When the manual driving forces are positive they act in the direction to move forward the wheelchair 30) and their absolute values are large as in a region A in FIGURE 12b, the advancing velocity increases at a high rate as shown in a region A in FIGURE 12a. When the manual driving forces are positive with their absolute values being small as in a region B (FIGURE 12b), the rate of increase of the wheelchair advancing velocity is gradual as shown in FIGURE 12a. When the manual driving forces applied are zero as in a region C in FIGURE 12b, the velocity of the wheelchair 30 does not change and the wheelchair moves forward by inertia as shown in FIGURE 12a in a region C.

When the manual driving forces are negative they act in the direction to move the wheelchair 30 backward) with their :-rm*---annmarrrrm ~nm3rb l sr I L^L I. i absolute values being small as in a region D in FIGURE 12b, the advancing velocity of the wheelchair 30 decreases gradually, as in a region D in FIGURE 12a. If the manual driving forces are negative and their absolute values are large as in a region E, the velocity decreases rapidly. it should be noted that FIGURES 12a and 12b represent an ideal condition in which there is no friction loss.

In the above description, simple acceleration and deceleration of the wheelchair 30 have been described. It should be noted that since the motors 76R and 76L are controlled independently of each other in response to the manual driving forces as exerted to and sensed by the manual-driving-force sensing units 50R and respectively, the wheelchair 30 can change its direction of movement. The direction changing operation of the wheelchair 30 is now described with reference to the following TABLE.

*i 4 441 44 4 *r 4 *4) 0 4 4 O4 4 4 4.r 4 4 h ii i 22.

ii 4

TABLE

Manual Driving Forces Case Movement of Wheelchair FIL FIR 1 0 0 Steady Movement 2 Small Small Small Acceleration 3 Large Large Large Acceleration 4 Small Small Small Deceleration Large Large Large Deceleration 6 Small Large Turning Left 7 Small Large Rapidly Turning Left 8 Large Large Rotating Counterclockwise 9 Large Small Turning Right 10 Large Small Rapidly Turning Right 11 Large Large Rotating Clockwise In Cases 1 through 5 In the TABLE, the manual driving forces ft f *f ftr f ftr QI JJ f ft ft ftftuu fttI ft f FIR and F1L acting on the manual-driving-force sensing units 50R and are equal to each other. Case 1 corresponds to the region C in FIGURE 12a, Case 2 corresponds to the region B, Case 3 corresponds to the region A, Case 4 corresponds to the region D, and Case corresponds to the region E of FIGURE 12a. In each of Cases the magnitude of the manual driving forces FIR and FIL are outside the dead zone 146 shown in FIGURE 10, which are sufficient to develop the electrical signals flR and fiL of magnitudes falling outside the dead zone shown in FIGURE 12a.

In each of Cases 6 through 11, the manual driving forces FIR and F1L differ from each other. In these cases, the motors 76R and 76L help the wheelchair 30 change its direction of movement.

In Case 6, the manual driving force F1L is in the positive direction and the absolute value of its magnitude is small, while the manual driving force FIR is also in the positive direction, but the absolute value of its magnitude is larger. In this case, the acceleration provided by the motor 76L and the acceleration provided by the manual driving force F1L the attendant exerts to the wheelchair 30 are summed and applied to the drive wheel 46L, while the sum of the acceleration provided by the motor 76R and the acceleration provided by the manual driving force FIR exerted by the attendant is applied to the drive wheel 46R. Although both manual driving forces FIR and FIL are in the same direction, the magnitude S of FIR is larger than that of FIL. Accordingly, the acceleration of the drive wheel 46R is larger than that of the drive wheel 46L.

This causes the motor-driven wheelchair 30 to turn left.

In Case 7, the manual driving force FIL is negative and its absolute value is small, while the manual driving force FIR is positive and its absolute value is large. In this case, the acceleration of the drive wheel 46R is similar to that In Case 6.

I9i it9 I I L: I 3 However, the acceleration of the drive wheel 46L is in the opposite direction to that in Case 6. Accordingly, the wheelchair 30 turns left rapidly.

In Case 8 where the manual driving force FIL is negative and large in absolute value, while the manual driving force FIR is positive and large in absolute value, the acceleration of the drive wheel 46R is similar to that in Case 6 and the acceleration of the wheel 46L is in the opposite direction to that in Case 6 and large.

Accordingly, the wheelchair 30 rotates counterclockwise.

In Case 9, the manual driving force F1L is positive and large in absolute value, whereas the manual driving force FIR is negative and small in absolute value. This situation is opposite to Case 6, and, therefore, the wheelchair 30 turns right.

When the manual driving force FIL is positive and large in absolute value, while the manual driving force FIR is negative and small in absolute value, as in Case 10, the wheelchair 30 turns right rapidly, which is opposite to Case 7.

In Case 11, the manual driving force F1L is positive and its absolute value is large, whereas the manual driving force FIR is negative and large in absolute value. This is a case opposite to Case 8, so that the wheelchair 30 rotates clockwise.

As described above, the accelerations of the motors 76R and 76L respectively coupled to the drive wheels 46R and 46L vary in accordance with the manual driving forces FIR and FIL, respectively, In order to control the acceleration and direction of movement of the wheelchair 30 as described, the CPU 94 in the signal converting unit 56 performs arithmetic operations as shown in the flow chart of FIGURE 13.

Immediately after the start of the arithmetic operation, a flag indicating which signal Is to be processed, a signal from the r.

A

manual-driving-force sensing unit 50R or a signal from the manualdriving-force sensing unit 50L, is set to, for example, a value which means that the signal from the unit 50R is to be processed (STEP S2). Next, whether the flag is set to or not is determined (STEP S4). If the flag is set to the judgment made by STEP S4 is YES), the digital signal DflR from the A/D converter 92 is read in the CPU 94 (STEP S6), and is stored therein as data fl for use in the succeeding arithmetic operations (STEP 8).

If it is determined in STEP S4 that the flag is set to "1" the judgment made in STEP S4 is NO), the digital signal DflL is read into the CPU 94 from the A/D converter 92 (STEP S10), and is stored therein as data fl for use in the succeeding arithmetic operations (STEP S12).

After STEP S8 or S12, the magnitude of the data fl is judged (STEP S14). If the data fl is 0, for example, which means that the data fl is within the dead zone, no acceleration is given to the wheelchair by the motor 76R or 76L.

Next, in order to process a signal from the other manualdriving-force sensing unit, judgment is made as to whether the flag is set to or not (STEP S16). If the answer is YES, the flag is o set to in order to next process the signal from the manual- S driving-force sensing unit 50L (STEP S18), and the processing Sreturns to STEP S4.

If the judgment made in STEP S16 is NO, the flag is set to "1" in order to next process the signal from the manual-driving-force sensing unit 50R (STEP S20), and the processing returns to STEP S4.

If the data fl is judged to be larger than 0 in STEP S14, an operation f2 K fl a is carried out (STEP S22). The amplifier 96 is controlled so that the result of the arithmetic operation, i.e. data f2, is developed as the motor-torque related digital signal Df2R (STEP S24).

On the other hand, if the data fl is judged to be less than 0 in STEP S14, an arithmetic operation f2 K fl P is performed (STEP S26), and the amplifier 96 is so controlled that the result of the arithmetic operation, i.e. data f2, is outputted as the motor-torque related digital signal Df2L (STEP S28).

Following STEP S24 or S28, STEPS S16 and S18 or STEPS S16 and are successively performed, and thereafter, STEP S4 is performed, in order to process the signal from the other manualdriving-force sensing unit.

In the manner as stated above, the digital electrical signals DflR and DflL are alternately read into the CPU 94, and the motors 76R and 76L are controlled to produce acceleration as determined by the signals OflR and DflL, respectively.

In the above-described embodiment, two drive wheels are used.

However, it may be arranged that four follower wheels are used at respective four corners of a wheelchair with a single drive wheel disposed intermediate between the two rear follower wheels.

ijKffaa

Claims (6)

1. A motor-driven vehicle comprising: a vehicle body having a handlebar; a drive wheel mounted to said vehicle body; electrical driving means for selectively driving said drive wheel in forward and reverse directions to thereby move said vehicle body; and manual-driving-force sensing means for sensing manual driving force exerted to said handlebar and generating forward and reverse ij control signals for controlling said electrical driving means; Ssaid manual-driving-force sensing means comprising: Sa displaceable grip mounted on an end of said handlebar, said grip being displaceable along the length of said handlebar; displacement sensing means for sensing the displacement of said grip and selectively generating said forward and reverse control signals in response to the sensed displacement of said grip; elastic means disposed within said displaceable grip for S" transmitting force exerted to said grip in the direction toward said handlebar or in the direction opposite thereto to said handlebar. t

2. The motor-driven vehicle according to Claim 1 wherein said manual-driving-force sensing means further comprises two stop members disposed spaced on and along the length of said grip and coupled to said handlebar, said two stop members being contacted by respective ones of the two ends of said elastic means; first releasing means responsive to the displacement of said grip in the direction toward said handlebar for releasing one of the two ends of said elastic means from its contact with an associated one of said two stop members and compressing said elastic means in the direction toward said handlebar; and second releasing means responsive to the displacement of said grip in the direction away from said handlebar for releasing the other of the two ends of said elastic means from its contact with the other of said two stop members and compressing said elastic means in the direction away from said handlebar.

3. A motor-driven vehicle comprising: a vehicle body having a handlebar; a drive wheel mounted to said vehicle body; electrical driving means for driving said drive wheel; and manual-driving-force sensing means for sensing manual driving force exerted to said handlebar in order to move said vehicle body, and generating a control signal for controlling said electrical driving means; said manual-driving-force sensing means comprising: a displaceable grip mounted on an end of said handlebar, said 444 grip being displaceable along the length of said handlebar; 'displacement sensing means for sensing the displacement of said grip and generating said control signal in response to the sensed oS4 displacement of said grip; elastic means disposed within said displaceable grip along the 00, length of said handlebar, said elastic means being compressed when said displaceable grip in its neutral position where said grip is displaced in neither direction, receives force in the direction toward or away from said handlebar, and returning said grip to said neutral position when said force is removed from said grip.

4. The motor-driven vehicle according to Claim 3 wherein said manual-driving-force sensing means further comprises: -I I -r I ~C L~ 1 two stop members disposed spaced from each other within and along the length of said displaceable grip, the respective ends of said elastic means contacting said two stop members; a first actuating member responsive to the displacement of said grip in the direction toward said handlebar for releasing the end of said elastic means remote from said handlebar from the contact with its associated one of said two stop members and compressing said elastic means in the direction toward said handlebar; and Ii a second actuating member responsive to the displacement of said grip in the direction away from said handlebar for releasing the end of said elastic means closer to said handlebar from the j contact with the other one of said two stop members and compressing said elastic means in the direction away from said handlebar. i

5. The motor-driven vehicle according to Claim 4 wherein said I elastic means is compressed with its two ends contacting said respective stop members when said displaceable grip is in its |i neutral position. S 20

6. The motor-driven vehicle according to Claim 5 wherein: said drive wheel is disposed on each side of said vehicle body; said electrical driving means is provided for each of said I drive wheels; i .said handlebar is provided in association with each of said drive wheels; and 'said manual-driving-force sensing means is provided for each of said handlebars and generates said control signal for the associated one of said drive wheels. DATED THIS 17TH DAY OF NOVEMBER 1995 NABCO LIMITED By its Patent Attorneys: GRIFFITH HACK CO. Fellows Institute of Patent Attorneys of AustraLia ABSTRACT OF THE DISCLOSURE A motor-driven vehicle includes a drive wheel mounted on a vehicle body. An electrical drive wheel driving unit, a battery, and a control unit for controlling the driving unit are disposed within the drive wheel. A manual-driving-force sensing unit is mounted on a handlebar of the vehicle, which generates a control signal in accordance with the magnitude and direction of a manual driving force applied to the handlebar. The control signal is fed to the control unit to control the electrical driving unit. s* r