Electric stroller improved driving stability and safety

Abstract

The present invention relates to an electric stroller that improves driving stability and safety by automatically driving based on the driving intention, driving speed, and driving direction determined by the magnitude of the force applied by a caregiver, and by stably driving automatically while coping with road surface conditions, left-right inclination of the road surface, and weight imbalance. More specifically, the invention involves installing a motor on each left and right rear wheel to rotate them individually, extracting user force in the forward / backward direction and user force in the rotational direction from the user force applied to the handle to calculate driving speed and turning speed, determining the rotational speed and direction of the left and right rear wheels according to the driving speed and the direction of the user force in the forward / backward direction, and then modifying them according to the turning speed and the direction of the user force in the rotational direction to independently control the rotational speed of the left and right rear wheels, and adjusting the rotational speed of the left and right rear wheels by detecting the left-right inclination of the road surface and the degree of weight imbalance.

Description

Technology Field

[0001] The present invention relates to an electric stroller that improves driving stability and safety by determining the driving intention, driving speed, and driving direction based on the magnitude of the force applied by a caregiver to drive automatically, and by responding to road surface conditions, left-right inclination of the road surface, weight imbalance, etc. to drive stably automatically. Background Technology

[0002] Strollers carrying infants and toddlers require a guardian to push them from behind to move, and since they also carry infant supplies or other heavy loads, they require a lot of effort depending on the road conditions, and it is difficult to turn in the direction the guardian wants when changing the route.

[0003] Accordingly, electric strollers are being developed and sold that drive at least some of the wheels with electric motors and control speed and turning based on the force applied by the caregiver to the handle.

[0004] Conventional technologies applied to such electric strollers included technologies that drive the wheels with individual electric motors to facilitate turning as intended by the caregiver, technologies that appropriately control speed on uphill and downhill slopes to apply force and drive safely as if moving on flat ground, technologies that use a regenerative braking motor to not only control speed on downhill slopes but also charge the battery, technologies that detect the surrounding environment including road surface conditions to appropriately control driving, and technologies that absorb shocks when passing over uneven road surfaces.

[0005] However, conventional technology lacks the ability to handle driving on a road surface inclined to the left or right in a direction perpendicular to the intended driving direction. For example, since sidewalks are generally slightly inclined toward the roadway, when driving in a straight line along the sidewalk, the vehicle may unintentionally veer toward the left or right inclined direction and deviate from the straight line. Consequently, the vehicle must be cumbersomely corrected every time this happens, and such deviation from the driving path can also occur when driving uphill.

[0006] Furthermore, conventional technology lacks the capability to cope with changes in driving posture caused by uneven road surfaces. In particular, when one wheel passes over a groove in the road surface, the stroller suddenly makes a sharp turn and changes its direction of travel; if the groove is deep, there is also a risk of tipping over.

[0007] Furthermore, conventional technology lacks the capability to precisely control turning by separately detecting the steering direction intended by the caregiver. That is, although the rotational speed or direction of each electric motor driving both wheels is configured to be individually controlled based on the magnitude and direction of the force applied to both sides of the handle, allowing the caregiver to adjust the turning angle and speed, it is difficult for the caregiver to control the system because the steering direction is not precisely extracted from the amount of handle operation. Prior art literature

[0008] (Patent Document 0001) KR 10-2283384 B1 2021.07.23.(Patent Document 0002) KR 10-1638242 B1 2016.07.04.(Patent Document 0003) KR 10-2022-0118326 A 2022.08.25.(Patent Document 0004) KR 10-2021-0122949 A 2021.10.13. The problem to be solved

[0009] The objective of the present invention is to provide an electric stroller that allows a caregiver to accurately, easily, and safely adjust the driving speed and direction, and ensures driving safety and stability when driving on roads inclined in the left and right directions and on roads with severe unevenness. means of solving the problem

[0010] To achieve the above objective, the present invention comprises an electric stroller configured such that a front wheel support frame (120) having a front wheel axle mounting part (122) rotatably installed for a front wheel (121) is freely pivotably coupled to both sides in the front width direction, a rear wheel support frame (130) having a rear wheel axle mounting part (132) rotatably installed for a rear wheel (131) is coupled to both sides in the rear width direction, and a handle frame (140) having a handle (141) provided at the top is connected to a seat frame (110) equipped with a seat (111). The invention further comprises: a motor (20) having an encoder (21) for measuring and controlling the rotational speed and a braking device (30) for braking the rear wheel (131), which is coupled to each of the two rear wheels (131) and supported by the rear wheel axle mounting part (130) so that the rear wheels (131) can be individually rotated in forward and reverse directions; and a touch sensor (40) installed on the handle (141) to detect contact. A twisting deformation sensor (50) installed at both ends of the handle (141) to measure the forward and backward pressure applied to both sides of the handle (141) by the user force applied to the handle (141); a battery (70) for power supply; and a control panel (10) for controlling the motor (20) are installed.

[0011] The control panel (10) is used to independently control the motor (20) by adding or subtracting the pressure applied to both sides of the handle (141) by the twisting deformation sensor (50) while contact is detected by the touch sensor (40), and when the user force in the front and rear direction is greater than or equal to a preset first lower limit value, it calculates the driving speed of the motor (20) in proportion to the difference between the user force in the front and rear direction and the first lower limit value, and when the user force in the rotational direction is greater than or equal to a preset second lower limit value, it calculates the turning speed in proportion to the difference between the user force in the rotational direction and the second lower limit value, and after determining the turning speed and turning direction of both rear wheels (131) according to the driving speed and the direction of the user force in the front and rear direction, it increases the turning speed of at least one of the rear wheels (131) or changes the turning direction according to the turning speed and the direction of the user force in the rotational direction.

[0012] The present invention according to one embodiment further includes a user interface (15) for inputting and setting the first lower limit value and the second lower limit value.

[0013] The present invention according to one embodiment includes a load cell (60) installed at the joint where the front wheel axle assembly (122) and the rear wheel axle assembly (132) are joined, for measuring the load applied to the front wheel axle assembly (122) and the rear wheel axle assembly (132); the control panel (10) is equipped with an inertia sensor (14) that detects the driving direction, the front-rear direction tilt, and the left-right direction tilt. When driving in a straight line, if the left-right direction tilt is detected by the inertia sensor (14), the rotational speed of the motor (20) in the tilted direction is accelerated and controlled according to the difference between the total load measured by the load cell (60) and the loads on both sides measured by the load cell (60) installed at the joint of the front wheel axle assembly (122) on both sides, and the rotational speed is adjusted according to the driving direction detected by the inertia sensor (14) to maintain a straight driving path.

[0014] In the present invention according to one embodiment, when the inertia sensor (14) detects a forward / backward tilt, if the difference between the loads on both sides detected by the load cells (60) installed at the joint portions of the rear wheel shafts (132) on both sides is greater than or equal to a preset value, the control panel (10) controls the rotational speed of the motor (20) on the side with the relatively larger load to be reduced.

[0015] In the present invention according to one embodiment, when the control panel (10) detects a momentarily reduced load in one of the load cells (60) installed at the joint portions of the rear wheel shafts (132) on both sides while driving in a straight line, it controls the motor (20) on the side opposite to the side with the reduced load to reduce the load, and then calculates the rotational speed of the motors (20) on both sides to restore the straight-line driving path when it is determined that the driving path has been deviated from according to the change in driving direction detected by the inertia sensor (14), and controls the motors (20) according to the calculated rotational speed.

[0016] In the present invention according to one embodiment, the motor (20) is equipped with a regenerative braking function and can be used as a generator. The control panel (10) charges the battery (70) by using the motor (20) as a generator when the total load measured by the load cell (60) is less than or equal to a preset value and the user force in the forward and backward directions is greater than or equal to the first lower limit value and less than or equal to an additional preset upper limit value, and uses the motor (20) as an electric motor when it exceeds the preset upper limit value.

[0017] According to one embodiment, the present invention comprises: a front wheel damper (80); a damper (91); a damper receiving part (82) that accommodates the damper (81), which is fixed to the front wheel axle mounting part (122) at its lower end and configured as a hollow tube shape with an upper opening, and has the load cell (60) installed at its upper end; and a cap block (83) that is fixed to the front wheel support frame (120), has the damper receiving part (82) inserted into the lower opening of the hollow end to allow pivoting and vertical movement, thereby applying a load to the damper (81); and a damper (91); a damper receiving part (92) that accommodates the damper (91), which is fixed to the rear wheel axle mounting part (132) at its lower end and configured as an upper opening of a square tube shape, and has the load cell (60) installed at its upper end. The rear wheel buffer (80) further comprises a cap block (93) that is fixed to the rear wheel support frame (130) and has a buffer receiving portion (92) inserted into the lower open rectangular internal space to allow only vertical movement so that a load is applied to the buffer (91).

[0018] On the outer surface of the above buffer receiving portion (82, 92), a groove (82a, 92a) having a predetermined width is formed vertically, and the cap block (83, 93) has a structure in which a lower block (83d, 93d) is inserted from above into the buffer receiving portion (82, 92) to surround the lower outer surface of the buffer receiving portion (82, 92), and an upper block (83a, 93a) is formed to receive the upper side of the buffer receiving portion (82, 92) through a side opening (83b, 93b) formed on one side, surround the upper outer surface and upper surface of the buffer receiving portion (82, 92), and is fitted into the groove (82a, 92a) of the buffer receiving portion (82, 92) and has a projection (83c, 93c) formed to prevent detachment so that it can move vertically. Effects of the invention

[0019] The present invention described in claim 1 prevents movement in situations where there is no user intent by driving or turning only when a certain force is applied, and enables accurate driving in accordance with the driving intent by detecting the applied force in separate speed and steering components according to the user's intent and controlling it in proportion to the applied force.

[0020] The present invention described in claim 2 allows anyone to use it without strain by inputting a reference value, which serves as a standard for judging the user's intent regarding speed and steering, into an appropriate value considering the user's physical strength.

[0021] The ball invention described in claim 3 can prevent unintended deviation from the driving path due to weight imbalance when moving on a road surface inclined in the left and right directions by adjusting the rotational speed of the left and right wheels according to the center of gravity imbalance.

[0022] The present invention, as described in claim 4, adjusts the rotational speed of the left and right drive wheels according to the load affecting the traction of the drive wheels, thereby enabling stable maintenance of the driving path, particularly when moving on an inclined surface, and preventing the risk of overturning caused by unintended turning.

[0023] The present invention described in claim 5 prevents rapid turning due to irregular road surface conditions by controlling the speed of one wheel, thereby ensuring stability during driving and automatically maintaining the driving path.

[0024] The present invention described in claim 6 can improve user convenience by determining the intention to charge a battery based on the applied force without user operation.

[0025] The present invention, as described in claim 7, mounts a load cell on a shock absorber to maintain not only cushioning but also more stable grip with the road surface, prevents damage to the load cell, measures a load with reduced instantaneous fluctuations, and utilizes the load measured by the load cell to promote safe and stable driving, while also ensuring ease of assembly and robustness. Brief explanation of the drawing

[0026] FIG. 1 is a front perspective view of an electric stroller according to an embodiment of the present invention. FIG. 2 is a front perspective view of an electric stroller before the seat (111) is installed. FIG. 3 is a rear perspective view of an electric stroller before the seat (111) is installed. FIG. 4 is a block diagram showing components for electric drive. FIG. 5 is an exploded perspective view of the front wheel buffer (80). FIG. 6 is a perspective view and a cross-sectional view of the front wheel buffer (80). FIG. 7 is an exploded perspective view of the rear wheel buffer (90). FIG. 8 is a perspective view and a cross-sectional view of the rear wheel buffer (90). FIG. 9 is a drawing showing various examples of user force in the forward and backward directions and user force in the rotational direction extracted according to the applied force (FL, FR) measured by the twisting deformation sensor (50) at both ends of the handle (141), and the driving trajectory when this force is applied. Specific details for implementing the invention

[0027] Hereinafter, embodiments of the present invention are described with reference to the attached drawings, showing specific examples so that those skilled in the art can easily implement the present invention.

[0028] In describing embodiments of the present invention, well-known components or circuit configurations used for electric drive and control, functions or control methods implemented in a combined form of software and hardware, and typical details are not described in detail, as a person skilled in the art to which the present invention pertains can embody them to implement the present invention.

[0029] In addition, the person pushing and driving the stroller is referred to as the user.

[0030] In addition, the terms 'Front,' 'Rear,' 'Left,' 'Right,' 'Up,' and 'Down,' which express direction, are based on the user pushing the stroller from behind. Specifically, 'Front' refers to the direction of pushing the stroller forward, and 'Rear' refers to the direction of pulling the stroller backward. 'Left' and 'Right' refer to directions parallel to the road surface and perpendicular to the front-rear direction, signifying the left and right directions of the user pushing or pulling the stroller. 'Up' and 'Down' refer to directions perpendicular to the road surface and perpendicular to the front-rear direction, signifying the normal direction to the road surface. In the explanation, the term 'width direction' is also used to mean the left-right direction.

[0031] In addition, the force applied by the user to the handle of the stroller is called the user force, the force of pushing or pulling the handle in the forward and backward directions is called the forward and backward user force, and the force of twisting the handle to rotate it on a plane parallel to the road surface is called the rotational user force.

[0033] As shown in the perspective view of FIGS. 1 to 3, the stroller according to an embodiment of the present invention is configured to include a seat frame (110), a front wheel support frame (120), a rear wheel support frame (130), and a handle frame (140) to provide a seat (111), a front wheel (121), and a rear wheel (131) and to provide a handle (141) that a user can grasp. A front wheel shock absorber (80) and a rear wheel shock absorber (90) are additionally installed on the frame (100) to absorb shock when driving on an irregular road surface.

[0034] And, as illustrated in the block diagram of FIG. 4, the electrically signal-connected state is illustrated, and as illustrated in the perspective views of FIG. 1 to 3, the control panel (10), motor (20), braking device (30), touch sensor (40), twist deformation sensor (50), load cell (60), and battery (70) are additionally installed on the frame (100) to form an electric stroller.

[0036] First, the parts constituting the above frame (100) are described, and the installation location or installation type of the components added for the electric stroller is also described.

[0037] The above seat frame (110) is a frame for mounting a seat (111) to seat an infant. As illustrated in FIG. 1, a seat base (112) made in a shape similar to a vehicle seat can be detachably mounted on the seat frame (110), and a car seat can be mounted on the seat base (112) to be used as a seat (111), but this is not limited thereto. A car seat can be detachably mounted directly on the seat frame (110) to be used as a seat (111), or a seat (111) made specifically for strollers can be fixedly mounted on the seat frame (110).

[0038] A housing housing the control panel (10) and battery (70) can be mounted on the bottom surface of the above seat frame (110).

[0039] The above-mentioned seat frame (110) is integrally formed with a front wheel support frame (120) extending downward in the front, a rear wheel support frame (130) extending downward in the rear, and a handle frame (140) extending upward in the rear. Although not described in detail here, for example, as described in detail in Registered Patent No. 10-2464139, it may be configured as a foldable stroller in which either the front wheel support frame (120) or the rear wheel support frame (130) is folded toward the other, and the handle frame (140) can be folded or lowered, and it may also be equipped with a storage box or pocket for storing infant supplies or the user's belongings.

[0040] At the front end of the above-mentioned front wheel support frame (120), one front wheel buffer (80) is provided on each side in the width direction, and a front wheel axle mounting part (122) installed to allow the front wheel (121) to rotate freely is connected to the front wheel buffer (80).

[0041] Here, the front wheel damper (80) is structured to allow the front wheel axle mounting part (122) to rotate freely with respect to a vertical axis, and has a damping function and a load measuring function, and is described with reference to the exploded perspective view of FIG. 5 and the perspective view (a) and cross-sectional view (b) of FIG. 6.

[0042] The front wheel axle mounting portion (122) rotatably supports the horizontal axis of the front wheel (121) so that the front wheel (121) can roll along the road surface, and the portion formed to extend upward is connected to the front wheel support frame (120) through the front wheel buffer portion (80).

[0043] The above front wheel buffer section (80) is configured in the shape of a hollow tube and includes a buffer receiving section (82) that is vertically connected to or fixed at the top of the front wheel axle section (122), a buffer (81) that expands and contracts vertically and buffers, for example, is configured as a spring, and has the load cell (60) placed at the top, and a cap block (83) that is externally fitted to the buffer receiving section (82) and connected to or fixed to the front wheel support frame (130) by creating a lower open internal hollow that can accommodate the buffer receiving section (82) with a slight gap.

[0044] Accordingly, the buffer receiving portion (82) inserted into the internal hollow of the cap block (83) can pivot and supports the lower end of the internally received buffer (81), and by causing the load cell (60) to be pressed against the ceiling surface of the internal hollow of the cap block (83), the load that is pressed by the front wheel support frame (120) is applied to the load cell (60) while moving up and down. That is, it cushions the impact caused by unevenness of the road surface and also has a load measurement function.

[0045] In order to make it easy to assemble and to construct it compactly and robustly, as shown in the exploded perspective view of FIG. 5, a groove (82a) having a predetermined width in the upper and lower direction is formed around the outer surface of the buffer receiving part (82). Then, the cap block (83) has a structure in which a lower block (83d) is inserted into the buffer receiving part (82) from the top to the bottom direction and surrounds the lower outer surface of the buffer receiving part (82), and an upper block (83a) is inserted through the side opening (83b) to form a side opening (83b) to accommodate the upper side of the buffer receiving part (82) and surrounds the upper surface. Here, on the inner surface of the upper block (83a), a projection (83c) is formed to have a vertical width smaller than the vertical width of the groove (82a), which allows it to move up and down while inserted into the groove (82a) of the buffer receiving portion (82). At this time, it is preferable for the projection (83c) to extend to the side opening (83b) as shown in the illustration.

[0046] Accordingly, the buffer receiving portion (82) is partially exposed through the side opening (83b) as can be seen in FIG. 6(a) with the upper block (83a) and lower block (83d) combined, but can rotate stably, and as can be seen in the exploded perspective view of FIG. 5 and the cross-sectional view of FIG. 6(b), it moves up and down but does not fall out of the cap block (83). Of course, an insert member that blocks the side opening (83b) may also be used.

[0048] At the rear end of the above rear wheel support frame (130), one rear wheel buffer (90) is provided on each side in the width direction, and a rear wheel axle mounting part (132) that supports the rear wheel (131) so as to be rotatable is connected to the rear wheel buffer (90).

[0049] According to the present invention, the motor (20) individually controls and drives each rear wheel (131). In a specific embodiment for this purpose, the motor is configured as an in-wheel motor equipped with an encoder (21) for measuring the rotational speed of the rear wheel (131) and controlling the rotational speed, and is coupled to each rear wheel (131) and mounted on the inside of the rear wheel (131). Additionally, a braking device (30) for braking the rear wheel (131) is integrated with the in-wheel motor and mounted on the rear wheel (131).

[0050] Accordingly, although the structure is publicly known and therefore not described in detail, the rear wheel shaft mounting portion (132) is equipped with a structure that fixes the shaft fixed to the stator of the in-wheel motor so as not to rotate, and includes wiring for supplying driving power to the in-wheel motor, measuring rotational speed using an encoder (21), and operating the braking device (30). In the case of the braking device (30), an electronic braking device may be used, but is not limited thereto; any device for braking the rear wheel (131) is sufficient, and it is sufficient to have components for operating the braking device (30).

[0051] And, the rear wheel buffer (90) has a buffering function and a load measuring function, but does not connect the rear wheel axle mounting part (132) to allow free rotation.

[0052] The rear wheel buffer (90) for this purpose includes, as shown in the exploded perspective view of FIG. 7 and the combined perspective view (a) and cross-sectional view (b) of FIG. 8, a buffer receiving part (92) that accommodates a buffer (91) with the load cell (60) attached to the top, which is connected or fixed in a vertical direction to the rear wheel axle mounting part (132) similar to the front wheel buffer (80), and a cap block (93) that is connected or fixed to the rear end of the rear wheel support frame (130) after being erected in a vertical direction and has a structure that surrounds the side and top surface of the buffer receiving part (92). In addition, the cap block (93) is also configured with a combined structure of an upper block (93a) and a lower block (93b), and the groove (92a) of the buffer receiving part (92), the side opening (93b) and the protrusion (93c) of the upper block (93a) are also formed so that they can be connected in the same way.

[0053] However, the difference from the above-mentioned front wheel buffer (80) is that the outer surface of the buffer receiving portion (92) has the shape of an outer square tube, and the inner surface of the cap block (93) also has the shape of an inner square tube, but with a slight gap from the buffer receiving portion (92). Accordingly, the buffer receiving portion (92) moves up and down inside the cap block (93) but does not rotate around a vertical axis.

[0054] In this way, the present invention, equipped with a front wheel shock absorber (80) and a rear wheel shock absorber (90), absorbs shocks from the road surface applied individually to the front left and right front wheels (121) and the rear left and right rear wheels (131), respectively, and also detects loads applied through the front wheel support frame (120) and the rear wheel support frame (130).

[0056] A handle (141) that a user can grip is provided on the top of the handle frame (140), and a touch sensor (40) for detecting contact of the user's hand gripping the handle (141) is installed on the handle (141).

[0057] And, as shown through the cover interior in FIGS. 2 and FIGS. 3, both ends of the handle (141) are each fixed to the handle frame (140) with a twisting deformation sensor (50). This twisting deformation sensor (50) can be placed on a square piece of wood after connecting the handle (141) and the handle frame (140) with a square piece of wood, as exemplified in FIG. 6 of Registered Patent No. 10-2283384, to measure the applied pressure according to the deformation of the piece of wood. Since this is a known configuration that can be implemented as a force sensor, pressure sensor, torque sensor, etc., as shown in various modified embodiments introduced in Registered Patent No. 10-2283384 and FIG. 8 of Published Patent No. 10-2021-0122949, a detailed description is omitted.

[0058] However, in the present invention, the twisting deformation sensor (50) is installed at each end of the handle (141) to extract the components of the user force in the forward and backward direction and the user force in the rotational direction applied to the handle (141) using the pressure measured at both sides of the handle (141) when the user force is applied to the handle (141).

[0060] The control panel (10) and battery (70), which are the remaining components for electric drive, are shown as being housed in a single enclosure and mounted on the lower part of the seat frame (110), but they may be separated and mounted in an appropriate location according to the structure of the frame (100).

[0061] The above battery (70) is intended to supply power for electric driving and is composed of a rechargeable secondary battery.

[0062] The above control panel (10) includes a controller (11), a motor driver (12), a charger (13), an inertial sensor (14), and a user interface (15).

[0063] The motor driver (12) is connected to each motor (20) individually to drive the motor (20) according to the control signal transmitted from the controller (11) and to control the forward / reverse rotation direction and rotation speed. The rotation speed is controlled so that the rotation speed measured by the encoder (21) converges to the target speed of the control signal.

[0064] The charger (13) is also connected to each motor (20) to charge the battery (70) with the power generated when the motor (20) is operated as a generator. Although not shown, it includes a switching switch that is switched by the control panel (10) to selectively operate either the motor driver (12) or the charger (13) to use the motor (20) as a driver or a generator.

[0065] The above inertial sensor (14) is for detecting the driving direction, forward / backward tilt, and left / right tilt of the stroller, and for this purpose may include an acceleration sensor, an angular velocity sensor, and a geomagnetic sensor.

[0066] The above user interface (15) allows the user to input the first lower limit value, the second lower limit value, and the upper limit value described later and use them as setting values, and may also be installed on the handle (141) for convenience.

[0067] The battery (70), motor driver (12), charger (13), inertial sensor (14), and user interface (15) described above, as well as the circuit configuration for selectively operating the motor driver (12) and charger (13), are components well known in the technical field to which the present invention belongs, so further detailed description is omitted.

[0069] Electric drive operation of both rear wheels >

[0070] Below, the control operation by the above controller (11) is described.

[0071] The above controller (11) includes a sensing unit (11a), a calculation unit (11b), and a control unit (11c), and stores a first lower limit value, a second lower limit value, and an upper limit value received through the user interface (15) to be used as setting values.

[0072] Here, the first lower limit is the minimum force magnitude for driving the motor (20) or using it as a generator, and the second lower limit is the minimum force magnitude for steering the stroller. The upper limit is the force magnitude for switching the motor (20) from being used as a generator to being used as a drive (i.e., an electric motor).

[0073] When user contact is detected through the touch sensor (40), the sensing unit (11a) detects the driving direction, forward / backward tilt, and left / right tilt through the inertia sensor (14), measures the pressure applied to both sides of the handle (141) through the twist deformation sensor (50), and measures the load applied to each front wheel (121) and rear wheel (131) through the load cell (60).

[0074] That is, sensing operations using the inertial sensor (14), twisting deformation sensor (50), and load cell (60) are performed only while user contact is detected.

[0076] The above calculation unit (12b) extracts components of user force in the forward and backward directions and user force in the rotational direction using the pressure measured on both sides of the handle (141).

[0077] If the pressure is used as a vector value, the origin coordinates of the pressure on both sides are aligned with the center of the width direction of the handle (141) and then added to extract the user force in the front-rear direction as a vector value, and the pressure on both sides is aligned with the origin coordinates of the pressure on one side and then subtracted to extract the user force in the rotation direction as a vector value.

[0078] To make it easier to understand, if we treat the applied pressure as an absolute value, it can be extracted as follows.

[0079] This explanation refers to the various examples in Fig. 9.

[0080] As illustrated in FIG. 9(a) and FIG. 9(b), if the pressure direction of both pressure forces (FL, FR) is the same (forward or backward), the pressure force is obtained by adding the pressure forces (FL, FR) on both sides (FL+FR); and as illustrated in FIG. 9(c), if the pressure direction of one pressure force (FR) is forward and the pressure direction of the other pressure force (FL) is backward, the pressure force is obtained by subtracting the relatively smaller pressure force (FL) from the relatively larger pressure force (FR). Of course, if the pressure directions of both pressure forces (FL, FR) are the same, the direction of the user force in the forward direction is determined by that pressure direction, and if they are not the same, the direction of the user force in the forward direction is determined by the pressure direction of the relatively larger pressure force.

[0081] The user force for rotation corresponds to the steering force applied by the user to the handle. As exemplified in FIG. 9(a) and FIG. 9(b), if the direction of pressure of both pressures (FL, FR) is the same (forward or backward), it is calculated as the difference (FR-FL) between the two pressures (FL, FR), and when pressure is applied only with the relatively larger pressure (FR), the direction in which the handle rotates is determined as the turning direction of the stroller. As exemplified in FIG. 9(c), if the direction of pressure of one pressure (FR) is forward and the direction of pressure of the other pressure (FL) is backward, it is determined as the sum of the two pressures (FL, FR) (FL+FR), and when pressure is applied with both pressures (FL, FR), the direction in which the handle rotates is determined as the turning direction of the stroller.

[0083] And, the above calculation unit (12b) calculates the driving speed of the motor (20) in proportion to the difference between the forward / backward user force and the first lower limit value only when the extracted forward / backward user force, as exemplified in FIG. 9(a) and FIG. 9(b), is greater than or equal to the preset first lower limit value. That is, if a forward / backward user force less than the first lower limit value is applied by a user or another object, or if a force intended to rotate is applied as in FIG. 9(c), it is determined that there is no intention to drive at speed, so there is no need to calculate the driving speed, and the driving speed is set to '0'.

[0084] Additionally, the above calculation unit (12b) calculates a turning speed (or steering speed) in proportion to the difference between the turning speed and the second lower limit when the turning speed user force is greater than or equal to the preset second lower limit, as exemplified in FIG. 9(b) and FIG. 9(c). That is, if a turning speed user force less than the second lower limit is applied by a user or another object, or if a force intended to drive in a straight line is applied as in FIG. 9(a), it is determined that there is no intention to turn, so there is no need to calculate the turning speed, and the turning speed is set to '0'.

[0085] However, when both driving speed and turning speed are calculated, since a portion of the force intended for turning is added to the forward and backward user force as a relative value, it is preferable to modify the forward and backward user force by, for example, subtracting the force obtained by subtracting the second lower limit value from the rotational user force, and then recalculating and modifying the driving speed based on the modified forward and backward user force.

[0087] When the above control unit (13c) calculates at least one of the driving speed and turning speed, it determines the rotational speed or rotational direction of both rear wheels (131) according to the calculated value, and controls the motor driver (12) to independently drive the motors (20) on both sides in the determined rotational speed or rotational direction.

[0088] That is, as exemplified in FIG. 9(a), when only the driving speed is calculated, the two motor drivers (12) are controlled according to a control signal that controls the rotational speed of both rear wheels (131) to the same driving speed, thereby driving along a straight driving trajectory. Of course, the rotational direction of both rear wheels (131) for this driving trajectory is determined according to the direction of the user force in the front and rear directions.

[0089] As illustrated in FIG. 9(c), when only the turning speed is calculated, the rear wheel (131) in the direction opposite to the turning direction is rotated, and the two motor drivers (12) are controlled according to a control signal that stops or rotates the rear wheel (131) in the opposite direction, thereby causing the stroller to rotate at a turning speed in place. Of course, the turning direction is determined by the direction of the user's force in the turning direction.

[0090] For example, the sum of the rotational speeds of both rear wheels (131) can be made to correspond to the value of the turning speed calculated according to the user force in the direction of rotation, so that the turning speed when only one rear wheel (131) is rotated and when both rear wheels (131) are rotated can be made almost the same.

[0091] As illustrated in FIG. 9(b), when both driving speed and turning speed are calculated, the rotational speed of both rear wheels (131), which is determined equally according to the driving speed, is modified according to the turning speed, and the two motor drivers (12) are controlled by a control signal to control the modified rotational speed, thereby driving along a trajectory that is driving and turning.

[0092] For example, among the two rear wheels (131) that determine the rotational speed according to the driving speed, only the rear wheel (131) on the side opposite to the turning direction can increase the rotational speed according to the turning speed.

[0094] In summary, the rotational speed and rotational direction of both rear wheels (131) are determined according to the driving speed and the direction of the user force in the front and rear directions, and then modified by increasing the rotational speed of at least one of the rear wheels (131) or changing the rotational direction according to the turning speed and the direction of the user force in the rotational direction (turning direction). Accordingly, when the driving speed is '0', it is determined according to the turning speed, and when the turning speed is '0', it is used as is determined by the driving speed.

[0096] Meanwhile, the control unit (11c) does not calculate both the driving speed and the turning speed, and when it has a value of '0', it controls the braking device (30) to stop the stroller, and also controls the braking device (30) to stop the stroller when no contact from the user is detected by the touch sensor (40). That is, the braking operation of the braking device (30) is released only when a certain force for driving or turning is applied in a situation where contact is detected by the touch sensor (40), and then the stroller is moved according to the driving speed or turning speed.

[0098] In addition, the control unit (11c) ensures safe driving by adaptively controlling the rotational speed of the motor (20) based on the road surface condition determined by the values ​​measured by the load cell (60) and the inertia sensor (14) while driving the stroller. Of course, the rotational speed of the motor (20) is controlled through the motor driver (12).

[0099] First, when driving in a straight line, a control signal is transmitted to the motor driver (12) to modify the rotational speed of both rear wheels (131) according to the change in driving direction detected by the inertia sensor (14), thereby controlling the rotational speed of the motor (20) to maintain a straight driving path. Of course, the control signal can be obtained by calculating the degree of deviation from the straight driving path according to the change in driving direction detected by the inertia sensor (14), and then calculating the rotational speed of both rear wheels (131) to return to the straight driving path.

[0100] Second, when driving in a straight line, safe driving is enabled when tilting to the left or right is detected by the inertia sensor (14).

[0101] Specifically, the total load is obtained by summing the loads measured from each load cell (60), and the degree of weight bias in the left and right tilted direction is obtained according to the difference between the loads measured by the load cells (60) installed in the front wheel buffers (80) on both sides among the load cells (60), and a speed addition amount proportional to the total load and also proportional to the weight bias is calculated, and a control signal is transmitted to the motor driver (12) to accelerate the rotational speed of the motor (20) in the tilted direction by the speed addition amount.

[0102] Accordingly, as the total load and weight bias increase, it prevents the vehicle from leaning to the left or right and avoids the risk of tipping over due to such tilting. Of course, as mentioned in the first method, the method of adjusting the direction according to the driving direction detected by the inertial sensor (14) is a method of adjusting the speed again according to the left or right tilt.

[0104] Third, when driving in a straight line, if the load measured by one of the load cells (60) installed on each of the rear wheel buffers (90) is momentarily reduced, the motor (20) on the side opposite to the side with the reduced load among the rear wheels (131) is decelerated. The amount of instantaneous load reduction that serves as the criterion for judging this situation can be the amount of load reduction that occurs when the rear wheel (131) passes through a groove on the road surface and gets stuck in the groove, causing the road surface grip to be significantly reduced. The amount of reduction in the rotational speed of the motor (20) may be proportional to the amount of load reduction.

[0105] Afterwards, when it is determined that the vehicle has deviated from the straight driving path based on the change in driving direction detected by the inertial sensor (14), the rotational speed of both motors (20) to restore the vehicle to the straight driving path is calculated, and the motors (20) are controlled according to the calculated rotational speed.

[0106] Fourth, when a forward-backward tilt is detected by the inertia sensor (14), if the difference in load measured by the load cell (60) installed on both rear wheel cushioning parts (90) is greater than a preset value, the rotational speed of the motor (20) coupled to the rear wheel (20) in the direction where the load is measured to be relatively larger among the two rear wheels (131) is reduced. In particular, when driving uphill, the load is concentrated on the rear wheel (131), and the road surface gripping force on the rear wheel (131) where the load is relatively larger among the two rear wheels (131) becomes higher than that of the opposite rear wheel. The higher the road surface gripping force, the less slippage occurs with the road surface, and the ratio of the actual driving distance to the rotational distance becomes higher. Accordingly, by reducing the rotational speed of the side with higher road surface gripping force to balance the driving distance by both rear wheels, it is possible to prevent the stroller from turning due to the difference in road surface gripping force between the two rear wheels.

[0108] Additionally, the control unit (11c) sets the load measured from a stroller without an infant or heavy object on it as a preset value, and if the total load obtained from the loads measured by all load cells (60) is less than or equal to the preset value, and the user force in the forward and backward directions obtained above is greater than or equal to the first lower limit value and less than or equal to the upper limit value, the motor (20) is used as a generator to charge the battery (70). Of course, the operation of the motor driver (12) is stopped, and instead the motor (20) is connected to the charger (13) so that the power produced by the motor (20), which rotates by driving with user force, is charged into the battery (70).

[0109] When the user force in the forward and backward directions exceeds the upper limit value, the motor driver (12) is connected to the motor (20), and the motor driver (12) is operated so that the motor (20) is used as an electric motor and driven by controlling the speed according to the user force.

[0110] In this way, by automatically using the motor (20) as a generator according to the load of the stroller and the user's force, there is no need to use it with special caution, and by detecting the user's intention to move by driving quickly as the upper limit value and operating it as an electric motor, it is not necessary to manually switch the operating mode of the motor (20) in this case. Explanation of the symbols

[0111] 10: Control panel 11: Controller 11a: Sensing unit 11b: Calculation unit 11c : Control unit 12: Motor driver 13: Charger 14: Inertia sensor 15 : User Interface 20 : Motor 21 : Encoder 30 : Braking system 40: Touch sensor 50: Torsion deformation sensor 60: Load cell 70 : Battery 80: Front shock absorber 81: Shock absorber 82: Shock absorber housing 82a : Home 83 : Cap block 83a : Top block 83b: Side opening 83c: Protrusion 83d: Lower block 90: Rear shock absorber 91: Shock absorber 92: Shock absorber housing 92a : Home 93 : Cap block 93a : Top block 93b: Side opening 93c: Projection 93d: Lower block 100 : Frame 110 : Seat frame 111 : Seat 112 : Seat base 120: Front wheel support frame 121: Front wheel 122: Front wheel axle mounting section 130: Rear wheel support frame 131: Rear wheel 132: Rear wheel axle mounting section 140: Handle frame 141: Handle

Claims

Claim 1 A stroller configured such that a front wheel support frame (120) with a front wheel axle mounting section (122) rotatably installed for a front wheel (121) is freely pivotally coupled to both sides in the front width direction, a rear wheel support frame (130) with a rear wheel axle mounting section (132) rotatably installed for a rear wheel (131) is coupled to both sides in the rear width direction, and a handle frame (140) with a handle (141) provided at the top is connected to a seat frame (110) on which a seat (111) is mounted, wherein the rear wheels (131) can be individually rotated forward and reverse by being coupled to each of the two rear wheels (131) and supported by the rear wheel axle mounting section (130), and a motor (20) equipped with an encoder (21) for measuring and controlling the rotational speed and a braking device (30) for braking the rear wheels (131); and a touch sensor (40) installed on the handle (141) to detect contact; A twisting deformation sensor (50) installed at both ends of the handle (141) to measure the forward and backward pressure applied to both sides of the handle (141) by the user force applied to the handle (141); a load cell (60) installed at each joint of the front wheel axle assembly (122) and the rear wheel axle assembly (132) to measure the load applied to the front wheel axle assembly (122) and the rear wheel axle assembly (132); a battery (70) for power supply; and a control panel (10) for controlling the motor (20);The control panel (10) is equipped with the above, and while the touch sensor (40) detects contact, it performs a summation or subtraction operation of the pressure applied to both sides of the handle (141) by the twisting deformation sensor (50) to extract the components of the forward / backward direction user force and the rotational direction user force applied to the handle (141); when the forward / backward direction user force is greater than or equal to a preset first lower limit value, it calculates the driving speed of the motor (20) in proportion to the difference between the forward / backward direction user force and the first lower limit value; when the rotational direction user force is greater than or equal to a preset second lower limit value, it calculates the turning speed in proportion to the difference between the rotational direction user force and the second lower limit value; after determining the rotational speed and rotational direction of both rear wheels (131) according to the driving speed and the direction of the forward / backward direction user force, it increases the rotational speed of at least one of the two rear wheels (131) or changes the rotational direction according to the direction of the turning speed and the direction of the rotational direction user force, and uses this to independently control the motor (20), driving direction, forward / backward direction tilt, and left / right direction. An electric stroller equipped with an inertia sensor (14) for detecting tilt, wherein when driving in a straight line, if left-right tilt is detected by the inertia sensor (14), the rotational speed of the motor (20) in the tilted direction is accelerated and controlled according to the difference between the total load measured by the load cell (60) and the load on both sides measured by the load cell (60) installed at the joint of the front wheel axle assembly (122) on both sides, and the rotational speed is adjusted according to the driving direction detected by the inertia sensor (14) to maintain a straight driving path, and when forward-backward tilt is detected by the inertia sensor (14), if the difference between the loads on both sides detected by the load cell (60) installed at the joint of the rear wheel axle assembly (132) on each side is greater than or equal to a preset value, the rotational speed of the motor (20) on the side with the relatively larger load is decelerated and controlled. Claim 2 An electric stroller according to claim 1, further comprising a user interface (15) for inputting and setting the first lower limit value and the second lower limit value. Claim 3 delete Claim 4 delete Claim 5 In claim 1, the control panel (10) controls the motor (20) according to the calculated rotational speed to restore the straight driving path when, during straight driving, it detects a momentarily reduced load in one of the load cells (60) installed at the joint portions of the rear wheel shafts (132) on both sides, and then, when it is determined that the straight driving path has been deviated according to the change in driving direction detected by the inertia sensor (14), it calculates the rotational speed of the motors (20) on both sides to restore the straight driving path. Claim 6 In claim 1, the motor (20) is equipped with a regenerative braking function and can be used as a generator, and the control panel (10) charges the battery (70) by using the motor (20) as a generator when the total load measured by the load cell (60) is less than or equal to a preset value and the user force in the forward and backward directions is greater than or equal to the first lower limit value and less than or equal to an additional preset upper limit value, and uses the motor (20) as an electric motor when it exceeds the preset upper limit value. Claim 7 In claim 1, the front wheel damper (80) comprises: a damper (81); a damper receiving part (82) that accommodates the damper (81), which is fixed to the front wheel axle mounting part (122), configured as a hollow tube shape with an upper opening, and has the load cell (60) installed at the top; and a cap block (83) that is fixed to the front wheel support frame (120), has the damper receiving part (82) inserted into the lower opening, is pivotable, and allows for vertical movement so that a load is applied to the damper (81); a damper (91); and a damper receiving part (92) that accommodates the damper (91), which is fixed to the rear wheel axle mounting part (132), configured as an upper opening square tube shape, and has the load cell (60) installed at the top. A rear wheel buffer (80) comprising: a cap block (93) that is fixed to the rear wheel support frame (130) and has a buffer receiving portion (92) inserted into the lower open rectangular internal space to allow only vertical movement so that a load is applied to the buffer (91); An electric stroller having a structure in which a groove (82a, 92a) having a predetermined width in the upper and lower direction is formed on the outer surface of the shock absorber receiving portion (82, 92), and the cap block (83, 93) is fitted onto the shock absorber receiving portion (82, 92) from above and surrounds the lower outer surface of the shock absorber receiving portion (82, 92), and an upper block (83a, 93a) is formed to receive the upper side of the shock absorber receiving portion (82, 92) through a side opening (83b, 93b) formed on one side, surround the upper outer surface and upper surface of the shock absorber receiving portion (82, 92), and prevent detachment by forming a projection (83c, 93c) that allows it to move up and down while fitted into the groove (82a, 92a) of the shock absorber receiving portion (82, 92).

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