CN110371093B

CN110371093B - Simple automatic actuator for automobile pedal

Info

Publication number: CN110371093B
Application number: CN201910680741.1A
Authority: CN
Inventors: 吴晓东; 乔邦峻
Original assignee: Shanghai Jiaotong University
Current assignee: Shanghai Jiaotong University
Priority date: 2019-07-26
Filing date: 2019-07-26
Publication date: 2021-08-20
Anticipated expiration: 2039-07-26
Also published as: CN110371093A

Abstract

The invention discloses a simple automobile pedal automatic actuator which comprises a first part and a second part which are connected through a pull wire. The first part comprises calipers, an end cover, a steel wire pull wire with an outer sleeve, an L-shaped part, a ball joint bearing, an adjusting rod, a pull wire sleeve rocker arm, a triangular support, a fixing frame and a hexagonal stud. Calliper is located the top of footboard lever, and the end cover is located the left side of calliper, and two bulb joint bearings are located the both ends of adjusting the pole respectively, and L shape part is located the upper end of adjusting the pole, and the cover rocker arm of acting as go-between links to each other with the overcoat of acting as go-between that acts as go-between, and the cover rocker arm of acting as go-between is set up to articulated triangle support, and the mount is located the below of triangle support, and the hexagonal stud is located the below of mount. The second part comprises a steering engine, a rocker arm, a pull wire sleeve fixing shaft and a steering engine fixing seat, wherein the rocker arm is fixed on a steering wheel of the high-torque steering engine, a double-lug head of the pull wire is hinged with the rocker arm, and the pull wire sleeve is hinged on the steering engine fixing seat through the fixing shaft.

Description

Simple automatic actuator for automobile pedal

Technical Field

The invention relates to the field of braking systems, in particular to a simple automatic automobile pedal actuator.

Background

The braking system of the vehicle is used for reducing the running speed of the vehicle according to the requirements of a driver, even maintaining the static state of the vehicle, and the normal work of the braking system is an important guarantee for safe running. The working principle of most brake systems on the market at present is as follows: when a driver steps on a brake pedal, a pedal lever increases the pedal force and then pushes a push rod of a brake main cylinder (a boosting device such as a vacuum booster is generally connected in series between the pedal lever and the push rod to reduce the required pedal force), hydraulic oil in the brake main cylinder is discharged and flows to a brake caliper (corresponding to a disc brake) or a brake wheel cylinder (corresponding to a drum brake) at a wheel through a brake oil pipe, a piston is pushed to enable a brake pad to be in contact with and pressed against a brake disc (or a brake drum), and the kinetic energy of a vehicle is consumed by utilizing the generated friction force and converted into the internal energy of a brake system, so that the vehicle is decelerated.

Since the birth of vehicle brake systems, the basic operation methods are manual treading, and the magnitude of the brake force is mainly controlled by the magnitude of the treading force. With the development of technology, brake systems with electronic assistance technology, such as Antilock Brake Systems (ABS) and active emergency brake systems (AEB), have emerged to further improve driving safety. The former controls the braking force taken by the driver, and the latter can take over the braking operation completely in certain situations. In recent years, the scale of research on automatic driving and remote driving is expanding, and automatic control and line control execution functions of a brake system are modified as necessary preconditions.

Autopilot and telematic studies require that the braking system of the test vehicle possess automatic or remote control capabilities. Currently, the related art implements this generally in a mechanical and electronic manner. An additional mechanical execution device is mechanically installed on an original vehicle braking system, the action of a driver is simulated to operate a brake pedal and the like, the cost is low, but the response is slow, and the following effect is poor; the more complicated mechanism of current scheme has higher requirement to the space of vehicle footboard rear to preventing hot wall, requires that footboard rear space is sufficient, and probably disturbs original manual operation, and the executor design needs have sufficient maximum force/moment output in addition, otherwise is difficult to guarantee to give full play to the original performance of braking system. The electronic control unit equipped by the original vehicle is used for directly controlling the output of the booster and the brake oil pressure by sending corresponding signals; the intelligent level of the vehicle is required to be higher, an additional hydraulic control system or a servo motor driving system is provided for supporting the brake-by-wire, and the implementation threshold and the cost are also higher.

Accordingly, those skilled in the art have endeavored to develop a simple automatic pedal actuator for an automobile.

Disclosure of Invention

In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is how to reduce the cost, and at the same time, the braking response speed is fast, and the vehicle itself is required to have a low level of intelligence, and the original manual operation is not disturbed.

In order to achieve the aim, the invention provides a simple automatic automobile pedal actuator which is characterized by comprising a first part and a second part, wherein the first part is positioned between a brake pedal and a firewall, the second part is positioned around the first part, and the first part and the second part are connected through a steel wire pull wire with a casing;

the first part comprises calipers, an end cover, a pedal lever stay wire, an L-shaped part, a first ball joint bearing, a second ball joint bearing, an adjusting rod, a stay wire sleeve rocker arm, a triangular support, a fixed frame cross beam, a fixed frame vertical beam and a hexagonal stud, the calipers are positioned above the pedal lever, the end cover is positioned on the left side of the calipers, the L-shaped part, the first ball joint bearing and the second ball joint bearing are positioned on the right side of the pedal lever, the first ball joint bearing is positioned at the lower end of the adjusting rod, the second ball joint bearing is positioned at the upper end of the adjusting rod, the L-shaped part is positioned at the upper end of the second ball joint bearing, the stay wire sleeve rocker arm is connected with a stay wire outer sleeve of the stay wire, the stay wire sleeve rocker arm is hinged to the triangular support, and the fixed frame cross beam is positioned below the triangular support, the fixing frame vertical beam is positioned above the fixing frame cross beam, and the hexagonal stud is positioned below the fixing frame vertical beam;

the second part comprises a large-torque steering engine, a steering engine rocker arm, a pull wire sleeve fixing shaft and a steering engine fixing seat, wherein the steering engine rocker arm is fixed on a steering wheel of the large-torque steering engine, double lug heads of the pull wire are hinged to the rocker arm, the pull wire sleeve is connected with the pull wire sleeve fixing shaft, the pull wire sleeve fixing shaft is arranged to be hinged to the steering engine fixing seat, and a rotating shaft of the steering engine fixing seat is parallel to a steering engine shaft.

Further, the caliper and the pedal lever are fixed by side bolts.

Furthermore, the end cover is connected with the caliper through a side bolt, a gap is reserved in the middle, and the pull wire can freely move in the gap.

Furthermore, the caliper and the end cover are provided with a same semicircular notch, and acting force is transmitted between the cylindrical head of the pull wire and the combination of the caliper and the end cover through the semicircular notch.

Further, the pull sleeve rocker arm is provided with a groove for the pull wire to pass through from the side.

Further, the fixed frame cross beam and the triangular support are fixedly connected through bolts.

Furthermore, the fixed frame cross beam and the fixed frame vertical beam are fastened through bolts, and the fixed frame cross beam can adjust the position and the angle relative to the fixed frame vertical beam.

The invention also discloses a control method of the simple automobile pedal automatic actuator, which is characterized by comprising the following steps in the working process:

1) in the automatic execution working condition, when the braking force needs to be increased, the output shaft of the steering engine of the second part rotates clockwise to a required angle to pull the pull wire, and the subsequent work is completed by the first part;

2) the pull wire of the first part is tightened, the calipers are drawn, the pedal lever is driven to rotate towards the direction of the firewall, and a push rod of a brake main cylinder is compressed to exert a braking effect on the wheel;

3) when the braking force needs to be reduced, the output shaft of the steering engine rotates anticlockwise to a required angle, at the moment, the pedal lever of the first part rebounds under the action of the brake main cylinder push rod and the reset spring, and meanwhile, the cylindrical stay wire head is pulled to enable the stay wire to be always kept straight.

Further, the relationship between the angular speed of the steering engine and the linear speed of the pull wire in the step 3) is nonlinear.

Further, when the working condition is manually executed, the stay wire of the first part does not move, the pedal lever rotates towards the direction of the firewall under the action of pedal force, the stay wire head is separated from the caliper at the moment, and the stay wire head and the caliper are not affected with each other.

On the basis of a mechanical type, aiming at the defects, the invention carries out split design on the actuating mechanism, the transmission mechanism and the driving mechanism are independently separated and work through a transmission stay wire, the core driving mechanism part can be randomly placed in a certain range, the requirement on the space behind the pedal is very small, and the invention is compatible with normal manual driving control. In addition, the brake control system does not need to carry out any secondary processing on the original brake assembly, is convenient to disassemble, assemble and debug, has a certain adjusting range of mechanical properties, and is suitable for low-cost modification of the brake control system of a common sample vehicle in automatic/remote driving research.

The cost is greatly reduced, the size is small, and the wire control chassis function transformation of the unmanned vehicle is convenient.

The device is convenient to install, has a structure adjusting function, and can realize the adaptation change of main parameters such as wire pulling travel, force range and the like for different vehicle types;

the actuating mechanism is simple, has the advantages of short response time, high transmission efficiency and the like, and meets the basic requirements of the center line control actuating function of the unmanned vehicle.

The device is compatible with normal manned control after installation, and only needs to return the stroke of the actuator to zero, so that the driving operation of manual braking is not influenced.

The conception, the specific structure and the technical effects of the present invention will be further described with reference to the accompanying drawings to fully understand the objects, the features and the effects of the present invention.

Drawings

FIG. 1 is a front view of a first portion of a simplified automotive pedal automatic actuator according to a preferred embodiment of the present invention;

FIG. 2 is a side view of a first portion of a simplified automotive pedal automatic actuator according to a preferred embodiment of the present invention;

FIG. 3 is a schematic diagram of the arrangement of the short moment arm of the first part of the simplified automatic pedal actuator for an automobile according to a preferred embodiment of the present invention;

FIG. 4 is a schematic diagram of the arrangement of the long moment arm of the first part of the simplified automatic pedal actuator for an automobile according to a preferred embodiment of the present invention;

FIG. 5 is a schematic diagram of the automatic execution state of the first part of the simplified automatic pedal actuator for a vehicle according to a preferred embodiment of the present invention;

FIG. 6 is a schematic diagram of the manual actuation of the first portion of the simplified automotive pedal automatic actuator according to the preferred embodiment of the present invention;

FIG. 7 is a schematic diagram of a second portion of a simplified automotive pedal automatic actuator according to a preferred embodiment of the present invention;

FIG. 8 is a schematic diagram of the motion state of the rocker arm wire-pulling mechanism of the second part of the simple automatic pedal actuator of the vehicle according to the preferred embodiment of the invention at different strokes.

Detailed Description

A preferred embodiment of the present invention will be described below with reference to the accompanying drawings for clarity and understanding of the technical contents thereof. The present invention may be embodied in many different forms of embodiments and the scope of the invention is not limited to the embodiments set forth herein.

In the drawings, structurally identical elements are represented by like reference numerals, and structurally or functionally similar elements are represented by like reference numerals throughout the several views. The size and thickness of each component shown in the drawings are arbitrarily illustrated, and the present invention is not limited to the size and thickness of each component.

Reference herein to "remote driving" refers to a technique in which a driver maneuvers a controlled vehicle away from and in real time. CAN: the controller local area network bus technology is a widely adopted communication method for automobile electronic equipment. PWM: the invention discloses a pulse width modulation signal which is used for controlling the angle of a steering engine.

As shown in fig. 1 and 2, the mechanical structure of the simple automatic pedal actuator for the automobile comprises a first part and a second part, wherein the first part is positioned between a brake pedal and a firewall, the second part can be optionally placed, and the first part and the second part are connected through a steel wire pull wire with a casing (a brake wire or a clutch wire with a proper specification can be used in the existing technology).

The first part comprises calipers 1, an end cover 3, a stay wire cylindrical head 4, a stay wire 5, a first ball joint bearing 6, an adjusting rod 7, an L-shaped part 8, a second ball joint bearing 9, a bent part 11 of a stay wire sleeve, a stay wire sleeve rocker arm 12, a rotating shaft 13, a rotating shaft 14, a triangular support 15, a fixed frame cross beam 16, a fixed frame longitudinal beam 17 and a hexagonal stud 18. The caliper 1 is positioned above the pedal lever 2 and is screwed and fixed through a side bolt. The end cover 3 is located on the left side of the caliper 1, a semicircular notch which is the same as the caliper 1 is formed in the right side of the end cover 3, the end cover 3 is connected with the caliper 1 through a side bolt, a gap is reserved in the middle of the end cover 3, and the pull wire 5 can freely move in the gap. The left upper part of the caliper 1 and the upper part of the end cover 3 are respectively provided with a semicircular gap, the diameter of the semicircular gap is the same as that of the cylindrical head 4 of the steel wire stay wire 5, and the semicircular gap is used for transmitting pressure when the semicircular gap is contacted with the cylindrical head 4. One end of the first ball joint bearing 6 is fixed on the caliper 1. The L-shaped part 8 is sleeved on the hinged pins of the pedal lever 2 and the main cylinder push rod 10 and serves as a base of the second ball joint bearing 9. The two ends of the adjusting rod 7 are respectively connected with the first ball joint bearing 6 and the second ball joint bearing 9, and the adjusting rod has the functions of providing an additional limit to prevent the calipers 1 which are only fixed by friction from sliding relative to the pedal lever 2; secondly, the distance between the two angle irons is adjusted by rotating the middle part of the adjusting rod, so that the force arm of the pull wire 5 is changed, and proper automatic execution sensitivity is obtained. The curved portion 11 of the wire cover is located at one end of the cylindrical head of the wire 5 and is rigid to force the direction of movement of the wire 5 to change by about 90 degrees. The pull wire sleeve rocker arm 12 is used for fixing the bent part 11 of the pull wire sleeve, and one side of the pull wire sleeve rocker arm is provided with a thin groove which is convenient for the pull wire 5 to pass through from the side; the pull wire sleeve rocker arm 12 is hinged to a triangular support 15 through two mutually perpendicular

rotating shafts

13 and 14 and can rotate in the horizontal and vertical directions so as to avoid the stress direction of the pull wire 5 from deviating from the axis of the tail end of the pull wire sleeve, which causes unnecessary friction and abrasion of the wire and the sleeve. The fixing frame for mounting the parts 9-15 on the vehicle comprises a cross beam 16 and two longitudinal beams 17, wherein the cross beam is fixedly connected with the triangular support 15, and the longitudinal beams are fixed on four bolts for connecting the original vehicle brake pedal assembly and the firewall through four hexagonal studs 18. The cross beam 16 and the two longitudinal beams 17 are screwed and fixed by a bolt penetrating through transverse and vertical slotted holes of the cross beam and the longitudinal beams respectively, the height and horizontal deviation of the cross beam can be adjusted in a larger range, and the angle can also be adjusted in a certain range (namely, the cross beam does not need to be horizontally installed) so as to adapt to different pedal assembly designs and adjust the sensitivity by matching with an adjusting rod.

As shown in fig. 3 and 4, the length of the moment arm of the first part of the simple automatic pedal actuator can be adjusted, so as to influence the sensitivity of automatic execution. Fig. 3 is a short moment arm (high sensitivity) setting, where the same pull-off stroke can drive the pedal lever 2 to rotate through a larger angle, i.e., higher sensitivity and faster response speed; but the required wire driving force is also larger and the control accuracy is degraded. Fig. 4 shows a long arm (low sensitivity) setup, with the advantages and disadvantages opposite to the former.

As shown in fig. 5, in the automatic execution state, the pulling wire is tightened, the caliper 1 is pulled, the pedal lever is driven to rotate towards the firewall direction, and the brake master cylinder push rod is compressed to brake the wheel.

As shown in fig. 6, when the working condition is manually executed, the stay wire 5 does not move relative to the outer sleeve, the pedal lever 2 rotates towards the direction of the firewall under the action of the pedal force, the stay wire cylindrical head 4 is separated from the caliper 1 at the moment, and the stay wire cylindrical head and the caliper 1 are not affected with each other (if the stay wire head is fixed on the caliper 1 all the time, the stay wire cylindrical head cannot bear enough tension due to too thin steel wires, the thicker steel wires have stronger toughness and cannot be bent at will, and the forced bending may generate plastic deformation or even fracture and the like).

As shown in fig. 7, the second part comprises a large-torque steering engine 19, a steering engine rocker arm 20, a pull wire 21, a thread 22, a pull wire sleeve fixing shaft 23 and a steering engine fixing seat 24. Big moment of torsion steering wheel 19 has multistage reduction gear group, steering wheel rocking arm 20 is fixed in on big moment of torsion steering wheel 19's the steering wheel, and the ears head of acting as go-between 21 is articulated with rocking arm 20, and the rocking arm 20 of removable different length should generally be adjusted with the cooperation of first part in order to reach the effect that the effective stroke of footboard is enough, act as go-between stroke make full use of, the suitable three of steering wheel effective stroke compromise. The pull wire sleeve of the pull wire 5 is provided with a section of thread 22 and two adjusting nuts, and is used for fixing the pull wire sleeve on a fixed shaft 23 of the pull wire sleeve (the two nuts are tightly attached to two sides of the opening of the fixed shaft), and the relative position of the pull wire sleeve and the fixed shaft can be changed by rotating the two adjusting nuts, so that the pull wire stroke can be more fully utilized, and the effective rotation angle range of the rocker arm 20 can be finely adjusted. The stay wire sleeve fixing shaft 23 is hinged on the steering engine fixing seat 24, and a rotating shaft of the stay wire sleeve fixing shaft is parallel to a steering engine shaft, so that the stay wire 5 is prevented from deviating from the axis of the tail end of the stay wire sleeve in the stress direction, and unnecessary friction and abrasion between the stay wire sleeve and the stay wire sleeve are avoided.

As shown in figure 8, when the simple automatic automobile pedal actuator is used and the braking force needs to be increased, the output shaft of the steering engine rotates clockwise to a required angle, and the pull wire 5 of the second part is pulled, so that the first part is operated to work. When the braking force needs to be reduced, the output shaft of the steering engine rotates anticlockwise to a required angle, at the moment, the pedal lever 2 of the first part rebounds under the action of the main cylinder push rod 10 and the reset spring, and meanwhile, the cylindrical stay wire head is pulled, so that the stay wire 5 is always kept straight. Since the rotation of the rocker arm 20 is converted into the linear motion of the pull wire 5 in the process, the angular velocity of the steering engine is not in a direct proportion relation with the linear velocity of the pull wire 5. Specifically, if the former is guaranteed to be unchanged, the latter will have a slower speed in the initial and final stages of the stroke than in the middle stage. This feature, although it would make the mapping algorithm of the control program more complex, brings some obvious benefits: the adjustment at the beginning of the stroke (i.e. when the pedal force is small) becomes finer and can be used to fine tune the vehicle speed; in the middle of the stroke, the faster movement speed can make the response of the device to the change of the target braking force more sensitive; at the end of the stroke, because the equivalent resistance arm is shortened, the pulling force that the same steering wheel torque can provide can be bigger, so the steering wheel that optional ultimate torque is littleer satisfies the requirement of maximum braking force to reduce weight and cost.

In the aspect of electronic control, after equipment on a controlled vehicle receives a wireless signal of a console, target travel information of a brake pedal is decoded and extracted, the target travel information is sent to a single chip microcomputer which is responsible for controlling an automatic actuator through a CAN bus, and the single chip microcomputer converts the target travel information into a PWM signal and sends the PWM signal to a steering engine. Due to the nonlinear characteristic of mechanism motion transmission, reverse nonlinear transformation needs to be implemented in the process of pedal target travel → CAN signal → PWM signal, and the means CAN be theoretical calculation (plane analytic geometry) or table lookup.

The foregoing detailed description of the preferred embodiments of the invention has been presented. It should be understood that numerous modifications and variations could be devised by those skilled in the art in light of the present teachings without departing from the inventive concepts. Therefore, the technical solutions available to those skilled in the art through logic analysis, reasoning and limited experiments based on the prior art according to the concept of the present invention should be within the scope of protection defined by the claims.

Claims

1. The simple automatic automobile pedal actuator is characterized by comprising a first part and a second part, wherein the first part is positioned between a brake pedal and a firewall, the second part is positioned around the first part, and the first part and the second part are connected through a steel wire pull wire with a casing;

the first part comprises calipers, an end cover, a pedal lever, a stay wire cylindrical head, a first stay wire, an L-shaped part, a first ball joint bearing, a second ball joint bearing, an adjusting rod, a bent part of a stay wire sleeve, a stay wire sleeve rocker arm, a rotating shaft, a triangular support, a fixed frame cross beam, a fixed frame vertical beam and a hexagonal stud, and the calipers are positioned above the pedal lever and are screwed and fixed through side bolts; the end cover is positioned on the left side of the caliper, a semicircular notch which is the same as the caliper is formed in the right side of the end cover, the end cover is connected with the caliper through a side bolt, a gap is reserved in the middle of the end cover, and the first pull wire can freely move in the gap; a semicircular notch is respectively arranged above the caliper and the end cover, the diameter of the semicircular notch is the same as that of the stay wire cylindrical head, and the semicircular notch is used for transmitting pressure when the semicircular notch is contacted with the stay wire cylindrical head; one end of the first ball joint bearing is fixed on the caliper; the L-shaped part is sleeved on the pedal lever and a hinge bolt of a main cylinder push rod and serves as a base of the second ball joint bearing; the two ends of the adjusting rod are respectively connected with the first ball joint bearing and the second ball joint bearing, and the adjusting rod has the functions of providing an additional limit to prevent the calipers which are only fixed by friction from sliding relative to the pedal lever, and adjusting the distance between two angle irons by rotating the middle part of the adjusting rod, so that the force arm of the first pull wire is changed, and proper automatic execution sensitivity is obtained; the bending part of the wire drawing sleeve is positioned at one end of the wire drawing cylindrical head and is rigid so as to force the movement direction of the steel wire drawing wire to change by about 90 degrees; the pull wire sleeve rocker arm is used for fixing the bent part of the pull wire sleeve, and a slot is formed in one side of the pull wire sleeve rocker arm, so that the first pull wire can conveniently penetrate through the slot from the side; the pull wire sleeve rocker arm is hinged to the triangular support through two mutually perpendicular rotating shafts and can rotate in the horizontal and vertical directions so as to prevent the first pull wire stress direction from deviating from the axis of the tail end of the pull wire sleeve, and unnecessary friction and abrasion between the wire and the sleeve are caused; the fixing frame used for mounting the second ball joint bearing, the main cylinder push rod, the bending part of the pull wire sleeve, the pull wire sleeve rocker arm, the two rotating shafts and the triangular support on the vehicle comprises a fixing frame cross beam and two fixing frame vertical beams, the fixing frame cross beam is fixedly connected with the triangular support, and the fixing frame vertical beams are fixed on four bolts used for connecting the original vehicle brake pedal assembly with a firewall through four hexagonal studs; the fixed frame cross beam and the two fixed frame vertical beams are screwed and fixed by respectively penetrating a bolt through the transverse and vertical slotted holes of the fixed frame cross beam and the fixed frame vertical beams, the height and horizontal deviation of the fixed frame cross beam can be adjusted within a larger range, and the angle can be adjusted within a certain range so as to adapt to different pedal assembly designs and coordinate with the adjusting rod to adjust the sensitivity;

the second part comprises a large-torque steering engine, a steering engine rocker arm, a second pull wire, a pull wire sleeve fixing shaft and a steering engine fixing seat, wherein the steering engine rocker arm is fixed on a steering wheel of the large-torque steering engine, a double lug head of the second pull wire is hinged with the rocker arm, the pull wire sleeve is connected with the pull wire sleeve fixing shaft, the pull wire sleeve fixing shaft is arranged to be hinged on the steering engine fixing seat, and a rotating shaft of the steering engine fixing seat is parallel to a steering engine shaft.

2. A control method based on a simple automobile pedal automatic actuator as claimed in claim 1, characterized in that, in the process of working, the control method comprises the following steps:

1) in the automatic execution working condition, when the braking force needs to be increased, the output shaft of the steering engine of the second part rotates clockwise to a required angle to pull the second pull wire, and the subsequent work is completed by the first part;

2) the first pull wire of the first part is tightened, the calipers are drawn, the pedal lever is driven to rotate towards the direction of the firewall, and a push rod of a brake main cylinder is compressed to brake the wheel;

3) when the braking force needs to be reduced, the output shaft of the steering engine rotates anticlockwise to a required angle, at the moment, the pedal lever of the first part rebounds under the action of the push rod of the brake main cylinder and the reset spring, and simultaneously, the pull wire cylindrical head is pulled, so that the first pull wire is always kept straight.

3. The control method according to claim 2, wherein the relationship between the angular velocity of the steering engine and the linear velocity of the second wire in step 3) is non-linear.

4. The control method of claim 2, wherein when the working condition is manually performed, the first portion of the first wire is not moved, the pedal lever is rotated toward the firewall under the action of the pedal force, and the wire pulling cylindrical head is separated from the caliper without mutual influence.