Abstract:
An apparatus and a system include an actuator assembly configured for controlling a movement of a manual mechanical linkage shaft in a manual brake system for a vehicle wheel. An electric motor drives the actuator assembly wherein a manually applied force to the manual mechanical linkage shaft is modulated or pulsed. A lock and release assembly is configured for engaging and disengaging the actuator assembly to and from the manual mechanical linkage shaft. Means actuates the lock and release assembly to engage the actuator assembly to the manual mechanical linkage shaft, and disengage the actuator assembly from the manual mechanical linkage shaft. An electronic controller controls the electric motor during a braking of the vehicle wheel to mitigate skidding of the vehicle wheel during the braking

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present Utility patent application claims priority benefit of the U.S. provisional application for patent Ser. No. 61/325,237 and entitled “Antiskid System For General Aviation Aircraft”, filed on 16 Apr. 2010 under 35 U.S.C. 119(e). The contents of this related provisional application are incorporated herein by reference for all purposes.] 
     
    
     FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not applicable. 
       REFERENCE TO SEQUENCE LISTING, A TABLE, OR A COMPUTER LISTING APPENDIX 
       [0003]    Not applicable. 
       COPYRIGHT NOTICE 
       [0004]    A portion of the disclosure of this patent document contains material that is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or patent disclosure as it appears in the Patent and Trademark Office, patent file or records, but otherwise reserves all copyright rights whatsoever. 
       FIELD OF THE INVENTION 
       [0005]    The present invention relates generally to brake systems for general aviation aircraft. More particularly, the invention relates to a low cost, antiskid brake system. 
       BACKGROUND OF THE INVENTION 
       [0006]    Electronic controlled antiskid systems are found on many wheeled vehicles including most cars, large airplanes and some motorcycles. These vehicles have powered hydraulic or pneumatic brake systems that work in conjunction with the antiskid system. These electronic controlled antiskid systems use wheels speed sensors, an electronic controller and control valves to regulate the brake pressure in the powered brake systems to reduce tire skids. These electronic controlled antiskid systems increase safety by improving directional control and shortening the stopping distance of the vehicle by reducing tire skids when braking These electronic controlled antiskid systems are also referred to as Antilock Brake Systems (ABS). 
         [0007]    Manual brake systems use the force from an operator&#39;s feet and/or hands to provide the energy to actuate and power hydraulic or mechanical brakes. These vehicles do not have powered hydraulic or pneumatic brakes. Examples of wheeled vehicles with manual brakes include general aviation aircraft, motorcycles, and bicycles. Although there are a large number of vehicles with manual brakes that would benefit from an electronic controlled antiskid system, to date there are few if any practical electronic controlled antiskid systems available for these vehicles. It is therefore an objective of the present invention to provide an antiskid brake system that is practical for use on these types of vehicles. 
         [0008]    Almost all electronic controlled antiskid systems in use today on wheeled vehicles require a powered hydraulic or pneumatic brake system for their operation. Power for these brake systems is generally provided from a hydraulic or pneumatic pump coupled to the vehicle&#39;s engine or an electric motor that gets its power from the vehicle&#39;s electrical system. 
         [0009]      FIG. 1  is a schematic diagram showing a powered hydraulic brake system with an electronic controlled antiskid system for an aircraft with two main wheels  115 , in accordance with the prior art. Hydraulic fluid is directed from a reservoir  100  to a hydraulic pump  102  via a hydraulic pipe  101 . Pump  102  is driven by a vehicle engine  103  or an electric motor  104  that is powered by the vehicle&#39;s electrical system. Hydraulic fluid is directed from pump  102  through a hydraulic pipe  105  to a relief valve  106  that ensures that the maximum hydraulic system pressure is not exceeded. The hydraulic fluid is directed to left and right metering valves  108  through hydraulic pipes  107 . 
         [0010]    An aircraft brake system allows the pilot to apply the brakes independently to left and right main wheels  115  by pressing on left and right brake pedals  109 . Left and right brake pedals  109  are connected to their respective metering valves  108 . When the pilot pushes on brake pedals  109 , metering valves  108  modulate the pressure of the hydraulic fluid through pipes  110  to brake cylinders  111 . Brake pistons  112  inside brake cylinders  111  are connected to brake pads  113 . When the pilot pushes on brake pedals  109 , brake cylinders  111  cause brake pads  113  to push against brake discs/drums  114  creating the friction to slow the turning brake discs/drums  114  that are connected to wheels  115 . This action slows or stops the aircraft. A back up system is required for some vehicles so they can be stopped if there is a loss of power to the brake system. On a powered hydraulic brake system, this can be accomplished by adding a hydraulic accumulator  124  to the brake system. 
         [0011]    The electronic controlled antiskid system needs to monitor the rotation of wheels  115  to determine when a skid is occurring or about to occur. This is done with wheel speed sensors  116  located at each wheel  115 . A tone ring  117  turns with wheel  115  and creates a magnetic field disruption that can be detected by wheel speed sensors  116 . Wheel speed sensor  116  and tone ring  117  are typically integrated into a single unit and located inside the axle on large aircraft. The wheel speed signals are sent to an electronic controller  119  using electrical cables  118 . Using the speeds from wheel speed sensors  116 , electronic controller  119  determines when a skid condition is occurring and sends a signal to required control valves  122  through electrical cables  120  to reduce the brake pressure. Hydraulic fluid is released from brake cylinders  111  through pipes  121 , through control valves  122  and through pipes  123  back to reservoir  100 . When controller  119  determines that the skid event is over, it commands required control valves  122  to close, and the brake system returns to its normal braking mode. 
         [0012]      FIGS. 2A and 2B  illustrate manual brake systems, according to the prior art.  FIG. 2A  is a schematic diagram showing a manual hydraulic brake system for a general aviation aircraft, and  FIG. 2B  is a schematic diagram showing a manual mechanical brake system for a motorcycle or bicycle. Manual brake systems use the force from the operator&#39;s feet and/or hands to provide the energy to actuate and power the hydraulic or mechanical brakes. Manual hydraulic brake systems are common on general aviation aircraft, motorcycles, and bicycles. These vehicles do not have powered hydraulic or pneumatic brakes. These vehicles use a separate hand or foot lever for each wheel that has a brake. 
         [0013]    Referring to  FIG. 2A , a manual hydraulic brake system for a right main wheel  115  is shown for a general aviation (GA) aircraft. There is also a duplicate manual hydraulic brake system for the left main wheel on the GA aircraft. The pilot provides the power for the actuation of the brakes by pushing on a brake pedal  200  with his foot. Brake pedal  200  is coupled to an input shaft  201  that is inserted into a hydraulic master cylinder  202 . Input shaft  201  is connected to a master cylinder piston  203  located inside master cylinder  202 . When the pilot pushes on brake pedal  200 , hydraulic fluid is moved out of master cylinder  202  and into a brake pipe  204  that is connected to a brake cylinder  111 . Fluid in brake pipe  204  is pushed into brake cylinder  111  thus moving a brake piston  112 . Brake piston  112  is connected to a brake pad  113 , which is pushed against a brake disc/drum  114  creating the friction to slow the turning brake disc/drum  114  that is connected to wheel  115 . This action slows or stops the aircraft. 
         [0014]    Manual mechanical brake systems are common on motorcycles and bicycles. These vehicles use a separate hand and/or foot lever for the front and rear wheels, which each have a brake. Referring to  FIG. 2B , a manual mechanical brake system for a motorcycle or bicycle is shown. Only the brake system for the rear wheel is shown. There is normally a manual mechanical brake system for the front wheel as well on motorcycles and bicycles. The vehicle operator provides the power for the actuation of the brakes by pushing or pulling on a brake lever  200  with his hand and/or foot. Brake lever  200  is coupled to a mechanical lever  206  with a rod or cable  205 . When the operator pushes or pulls on brake lever  200 , mechanical lever  206  pulls or pushes on a rod or cable  207  that is connected to a mechanical lever  208  that is connected to a brake pad  113 , which is pushed against a brake disc/drum  114  creating the friction to slow the turning brake disc/drum  114  that is connected to a wheel  115 . This action slows or stops the vehicle. The number and arrangement of rods, cables and levers in different manual mechanical brake systems varies depending on the geometry of the vehicle. 
         [0015]    Hybrid manual brake systems exist that combine hydraulic and mechanical linkages to couple the operator&#39;s hand and/or foot movements to operate and power the brake mechanism. The brake pads in these hybrid manual brake systems can be mechanically or hydraulically actuated. 
         [0016]    There are currently known electronically controlled antiskid systems for manual hydraulic brake systems for motorcycles, however, there are no electronically controlled antiskid systems for manual mechanical brakes like those used on motorcycles and bicycles. As illustrated by way of example in  FIG. 1 , today&#39;s electronically controlled antiskid systems are not well suited for vehicles with manual brakes since a power source for the brake system must be added to the vehicle. This is typically not practical due to the added weight, cost and the difficulty of mounting the many needed components. This is the reason there are so few electronically controlled antiskid systems today for wheeled vehicles with manual brakes. There are several currently known mechanical antiskid devices, not systems, for bicycles with manual brakes. However, these mechanical devices offer reduced antiskid performance when compared to electronically controlled antiskid devices. 
         [0017]    In view of the foregoing, there is a need for improved techniques for providing a low cost, electronically controlled antiskid system that may be implemented in a practical manner on manual brakes. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]    The present invention is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings and in which like reference numerals refer to similar elements and in which: 
           [0019]      FIG. 1  is a schematic diagram showing a powered hydraulic brake system with an electronic controlled antiskid system for an aircraft with two main wheels, in accordance with the prior art; 
           [0020]      FIGS. 2A and 2B  illustrate manual brake systems, according to the prior art.  FIG. 2A  is a schematic diagram showing a manual hydraulic brake system for a general aviation aircraft, and  FIG. 2B  is a schematic diagram showing a manual mechanical brake system for a motorcycle or bicycle; 
           [0021]      FIGS. 3A ,  3 B and  3 C are schematic diagrams showing an exemplary manual brake system for one wheel on a vehicle, in accordance with an embodiment of the present invention.  FIG. 3A  is an overall view of a simple hydraulic system with three alternate locations for a lock and release assembly and an actuator assembly, and  FIG. 3B  is a close-up view of a fourth alternate location for the lock and release assembly and the actuator assembly in the simple hydraulic system.  FIG. 3C  is an overall view of a more complex mechanical system with six alternate locations for the lock and release assembly and the actuator assembly; 
           [0022]      FIGS. 4A and 4B  are schematic diagrams illustrating an exemplary electronic controller for an antiskid system for manual brakes, in accordance with an embodiment of the present invention.  FIG. 4A  shows the electronic control as an On/Off switch, and  FIG. 4B  shows the electronic control with the addition of a rheostat; 
           [0023]      FIG. 5  is a schematic diagram of an exemplary electronic controller in an electronically controlled antiskid system installed on two wheels of a vehicle, in accordance with an embodiment of the present invention; 
           [0024]      FIGS. 6A through 6K  illustrate eleven different exemplary methods to drive an actuator assembly, in accordance with embodiments of the present invention.  FIG. 6A  shows a piston.  FIG. 6B  shows a bellows actuator.  FIG. 6C  shows an inflatable accumulator.  FIG. 6D  shows a motor with a screw.  FIG. 6E  shows the motor with helical gears.  FIG. 6F  shows the motor with a worm gear.  FIG. 6G  shows the motor with a gear and a gear rack.  FIG. 6H  shows the motor with scissor arms.  FIG. 6I  shows the motor with a cam.  FIG. 6J  shows the motor with a lever arm.  FIG. 6K  shows an electric solenoid; 
           [0025]      FIGS. 7A through 7J  illustrate ten different exemplary methods of connecting a lock and release assembly to a brake linkage shaft, in accordance with embodiments of the present invention.  FIG. 7A  shows a locking tab method.  FIG. 7B  shows a locking clamp method.  FIG. 7C  shows a wire lock method.  FIG. 7D  shows a tapered wedge method.  FIG. 7E  shows a dual cam lock method.  FIG. 7F  shows a strap clamp method.  FIG. 7G  shows a locking collar method.  FIG. 7H  shows an external fork method.  FIG. 7I  shows an iron particle method, and  FIG. 7J  shows a hydraulic piston method; 
           [0026]      FIG. 8  is a side view of an exemplary electric master cylinder (EMC) with an integrated actuator assembly, in accordance with an embodiment of the present invention; and 
           [0027]      FIG. 9  is a side view of an exemplary wheel speed sensor attached to a brake caliper located on a main wheel, in accordance with an embodiment of the present invention. 
       
    
    
       [0028]    Unless otherwise indicated illustrations in the figures are not necessarily drawn to scale. 
       SUMMARY OF THE INVENTION 
       [0029]    To achieve the forgoing and other aspects and in accordance with the purpose of the invention, an apparatus and a system for mitigating wheel skidding in a manual brake system is presented. 
         [0030]    In one embodiment an apparatus includes means for controlling a movement of a manual mechanical linkage shaft in a manual brake system for a vehicle wheel, and means for directing the actuator assembly to control the movement of the manual mechanical linkage shaft during a braking of the vehicle wheel where the control of the movement mitigates skidding of the vehicle wheel during the braking Another embodiment further includes means for engaging and disengaging the controlling means to and from the manual mechanical linkage shaft. Yet another embodiment further includes means for driving the controlling means where a manually applied force to the manual mechanical linkage shaft is modulated to mitigate the skidding of the vehicle wheel during the braking Still another embodiment further includes means for actuating the engaging and disengaging means. Another embodiment further includes means for forming a unit suitable for replacing a manual hydraulic master cylinder of the manual brake system. Yet another embodiment further includes means for enabling the apparatus to be added to a hydraulic line of the manual brake system. 
         [0031]    In another embodiment an apparatus includes an actuator assembly configured for controlling a movement of a manual mechanical linkage shaft in a manual brake system for a vehicle wheel. An electronic controller directs the actuator assembly to control the movement of the manual mechanical linkage shaft during a braking of the vehicle wheel where the control of the movement mitigates skidding of the vehicle wheel during the braking Another embodiment further includes a lock and release assembly configured for engaging and disengaging the actuator assembly to and from the manual mechanical linkage shaft. In yet another embodiment the apparatus is configured as an addition to the manual brake system. Still another embodiment further includes an electric servomotor for driving the actuator assembly where, under direction of the electronic controller, a manually applied force to the manual mechanical linkage shaft is modulated to mitigate the skidding of the vehicle wheel during the braking In another embodiment the actuator assembly includes a cam and cam followers disposed about the manual mechanical linkage shaft for moving the manual mechanical linkage shaft. In yet another embodiment the lock and release assembly includes a locking tab including a hole configured for engaging the actuator assembly to the manual mechanical linkage shaft. Still another embodiment further includes an electric solenoid for actuating the lock and release assembly to engage the actuator assembly to the manual mechanical linkage shaft, and a release spring for disengaging the actuator assembly from the manual mechanical linkage shaft. Another embodiment further includes a master cylinder joined to the actuator assembly, electric servomotor, lock and release assembly, and the electric solenoid for forming a unit suitable for replacing a manual hydraulic master cylinder of the manual brake system, thereby adding the apparatus to the manual brake system. In yet another embodiment the actuator assembly, electric servomotor, lock and release assembly, and the electric solenoid are centrally located about a linkage shaft joined to the master cylinder enabling the actuator assembly, electric servomotor, lock and release assembly, and the electric solenoid to be positioned in a plurality of positions for facilitating adding the apparatus to the manual brake system. Still another embodiment further includes a hydraulic cylinder having a mechanical linkage suitable for engaging the lock and release assembly and the actuator assembly for enabling the apparatus to be added to a hydraulic line of the manual brake system. 
         [0032]    In another embodiment a system includes means for controlling a movement of a manual mechanical linkage shaft in a manual brake system for a vehicle wheel, means for driving the controlling means wherein a manually applied force to the manual mechanical linkage shaft is modulated or pulsed, means for engaging and disengaging the controlling means to and from the manual mechanical linkage shaft, means for actuating the engaging and disengaging means, and means for controlling the driving means during a braking of the vehicle wheel to mitigate skidding of the vehicle wheel during the braking Another embodiment further includes means for generating a signal including rotational information of the wheel. Yet another embodiment further includes means for automatically activating or deactivating the system in response to changes in force or pressure. Still another embodiment further includes means for powering the system. Another embodiment further includes means for engaging and disengaging the system, and for varying a frequency of the pulsed force. 
         [0033]    In another embodiment a system includes an actuator assembly configured for controlling a movement of a manual mechanical linkage shaft in a manual brake system for a vehicle wheel. An electric motor drives the actuator assembly wherein a manually applied force to the manual mechanical linkage shaft is modulated or pulsed. A lock and release assembly is configured for engaging and disengaging the actuator assembly to and from the manual mechanical linkage shaft. Means actuates the lock and release assembly to engage the actuator assembly to the manual mechanical linkage shaft, and disengage the actuator assembly from the manual mechanical linkage shaft. An electronic controller controls the electric motor during a braking of the vehicle wheel to mitigate skidding of the vehicle wheel during the braking Another embodiment further includes a tone ring and a wheel speed sensor for generating a signal including rotational information of the wheel, the tone ring and the wheel speed sensor being configured for joining to an outside of the wheel&#39;s axel. In yet another embodiment the tone ring includes a gear shape on a circumference of a disc. In still another embodiment the electronic controller uses GPS information to determine ground speed of the vehicle. In another embodiment the electronic controller includes a portable computing device. In yet another embodiment the portable computing device provides a vehicle&#39;s operator with audio and/or visual signals during a skidding event. Still another embodiment further includes at least one switch for automatically activating or deactivating the system in response to changes in force or pressure. Another embodiment further includes a portable battery supply for powering the system. Yet another embodiment further includes an operator control for engaging and disengaging the system, and for varying a frequency of the pulsed force. 
         [0034]    Other features, advantages, and aspects of the present invention will become more apparent and be more readily understood from the following detailed description, which should be read in conjunction with the accompanying drawings. 
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0035]    The present invention is best understood by reference to the detailed figures and description set forth herein. 
         [0036]    Embodiments of the invention are discussed below with reference to the Figures. However, those skilled in the art will readily appreciate that the detailed description given herein with respect to these figures is for explanatory purposes as the invention extends beyond these limited embodiments. For example, it should be appreciated that those skilled in the art will, in light of the teachings of the present invention, recognize a multiplicity of alternate and suitable approaches, depending upon the needs of the particular application, to implement the functionality of any given detail described herein, beyond the particular implementation choices in the following embodiments described and shown. That is, there are numerous modifications and variations of the invention that are too numerous to be listed but that all fit within the scope of the invention. Also, singular words should be read as plural and vice versa and masculine as feminine and vice versa, where appropriate, and alternative embodiments do not necessarily imply that the two are mutually exclusive. 
         [0037]    The present invention will now be described in detail with reference to embodiments thereof as illustrated in the accompanying drawings. 
         [0038]    Detailed descriptions of the preferred embodiments are provided herein. It is to be understood, however, that the present invention may be embodied in various forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, but rather as a basis for the claims and as a representative basis for teaching one skilled in the art to employ the present invention in virtually any appropriately detailed system, structure or manner. 
         [0039]    It is to be understood that any exact measurements/dimensions or particular construction materials indicated herein are solely provided as examples of suitable configurations and are not intended to be limiting in any way. Depending on the needs of the particular application, those skilled in the art will readily recognize, in light of the following teachings, a multiplicity of suitable alternative implementation details. 
         [0040]    At least some preferred embodiments of the present invention provide an electronically controlled antiskid system for wheeled vehicles with manual brakes to increase safety by improving directional control and shortening the stopping distance by reducing tire skids while braking when compared to conventional manual brake systems. At least some preferred embodiments are used with manual brake systems where the vehicle&#39;s operator uses their hands and/or feet to actuate and power the mechanical or hydraulic brakes. At least some preferred embodiments do not use any hydraulic or pneumatic power to apply the brakes. Instead, at least some preferred embodiments use an electronic controller and a wheel speed sensor to detect a tire skidding event on a wheeled vehicle and command an actuator to move the brake linkage to reduce the brake force that the operator is applying to the brake pads of the skidding wheel and thus reduce the tire skids. In at least some preferred embodiments, electrical power from the vehicles&#39; electrical system is used to power the antiskid system, including the actuators. At least some preferred embodiments can operate on either DC or AC power. In addition, some embodiments can operate on portable battery power, which is ideal for bicycle applications that have no on-board electrical systems. 
         [0041]    As illustrated by way of example in  FIG. 1 , today&#39;s electronically controlled antiskid systems are not well suited for vehicles with manual brakes because a power source for the brake system must be added to the vehicle. This is not practical due to the added weight, cost and the difficulty of mounting the many needed components. At least some preferred embodiments of the present invention provide the same safety benefits for vehicles with manual brake systems without the need for all of the additional components required for a vehicle with powered brakes. Antiskid systems according to at least some preferred embodiments weigh and cost less and are more compact than antiskid systems for powered brakes since there is no need for a hydraulic or pneumatic pump, a drive motor, control valves, relief valves and piping. In at least some preferred embodiments, the actuator that moves the brake linkage can be located anywhere in the brake linkage system. This can reduce the cost of retrofitting the antiskid system into vehicles already in use. At least some preferred embodiments may also reduce maintenance costs by extending tire life by reducing tire skids and tire blowouts and may reduce the cost of vehicle insurance by reducing the number of accidents caused by loss of directional control when braking 
         [0042]    In typical use of at least some preferred embodiments, the manual brake system already in place and certified on a vehicle is not impacted by the addition of the antiskid system. All elements of a manual brake system, shown by way of example in  FIGS. 2A and 2B , remain operational on the vehicle when the electronically controlled antiskid system is not operating. This is important for aircraft where re-certifying the entire brake system is impractical due to the added cost and the need to comply with the most current certification requirements. At least some preferred embodiments can be retrofit on vehicles already in operation or may be installed in new production vehicles as they are being manufactured. In some cases, a retrofit can be performed by replacing the current master cylinder with a plug and play replacement called an electric master cylinder. 
         [0043]    In at least some preferred embodiments, the electronic controller of the antiskid system for manual brakes can be adapted from electronic controllers for antiskid systems for powered brakes. This includes both analog and digital controller designs that are available today. In addition, antiskid software algorithms for powered brake systems can also be adapted to be used in at least some preferred embodiments. Adapting current antiskid electronics and software for the electronic controller in at least some preferred embodiments is attractive to perspective manufacturers in the antiskid brake business as it can reduce both the development time and cost to manufacture. 
         [0044]    Most currently known antiskid controllers compare the wheel speeds of all of the wheels on the vehicle to determine if a skidding event is occurring or about to occur with one or more of the wheels. Some electronic controllers use software algorithms to estimate the vehicle&#39;s “reference” or ground speed. Other antiskid controllers use inputs from other systems on board the vehicle to determine the estimated ground or reference speed. A function that can be added to some embodiments of the present invention is a Global Positioning System (GPS) capability that calculates the ground speed of the vehicle using GPS satellite data. 
         [0045]    At least some preferred embodiments of the present invention may be implemented with an advanced controller for aircraft and motorcycles applications or a basic controller sufficient for bicycle applications. For example, without limitation, a simple version of the electronic controller may be used on off road bicycles when a cyclist needs to maintain maximum braking and directional control when riding down a step dirt hill. In this non-limiting example, the electronic controller is an ON/OFF switch that the cyclist holds “ON” to engage the antiskid actuator in a “pulse the brakes mode” when the antiskid function is needed. 
         [0046]    At least some preferred embodiments of the present invention may utilize either type of automotive wheel speed sensors: the variable-reluctance or the magneto-resistive type of sensor. These sensors are environmentally rugged, lightweight, compact and low cost, and magneto-resistive wheel speed sensors can operate down to zero wheel speeds. Furthermore, wheel speed sensors in at least some preferred embodiments are not mounted inside the axle of the wheel. Wheel speed sensors typically use a gear shaped device called a tone ring to disrupt the magnetic field around the wheel speed sensor. Aircraft wheel speed sensors integrate the tone rings with the senor into a single unit that is mounted inside the aircraft&#39;s axle. This is not practical on general aviation aircraft due to the small axle diameters. The wheel speed sensor used in at least some preferred embodiments is located outside the axle. In addition in at least some preferred embodiments, the tone ring can be integrated into the brake disc for vehicles that utilize a disc brake. This is done by forming a gear shape in the outside or inside diameter of the brake disc. This can be done on aircraft, motorcycles or bicycles and can reduce weight and system complexity. 
         [0047]    There are several groups of people that could benefit from an electronically controlled antiskid system for vehicles with manual brakes in accordance with at least some preferred embodiments of the present invention. Pilots of general aviation (GA) aircraft can utilize at least some preferred embodiments to increase safety and reduce operating costs. The landing phase of flight has the highest accident rate and loss of direction control is the biggest accident factor in this category. Having an antiskid system available for GA aircraft pilots could improve aircraft safety and increase pilots&#39; peace of mind. Flight schools may also be interested in having the antiskid function according to at least some preferred embodiments on their GA aircraft since they typically experience two blown tires a year per aircraft from excessive braking by students. Manufacturers of GA aircraft with manual brake systems may also be interested in at least some preferred embodiments, as they could create more sales. With at least some preferred embodiments, manufacturers of aircraft brakes and antiskid systems would be able to enter the untapped retrofit market with over 200,000 GA airplanes flying today with manual brakes and no antiskid system available for these aircraft. Motorcycle manufactures may be interested in at least some preferred embodiments for motorcycles with manual brakes as many motorcycle manufacturers continue to provide more safety features on their vehicles, similar to cars to promote safety and increase sales. At least some preferred embodiments would be particularly beneficial for motorcycles that are operated in wet or icy conditions. With at least some preferred embodiments manufacturers of motorcycle brakes would also be able to enter the untapped retrofit market with millions of motorcycles in use today with manual brakes and no antiskid system available for these vehicles. Bicycle manufactures may be interested in at least some preferred embodiments for bicycles operated in wet and icy conditions and for bicycles operated by off-road cyclists that need enhanced skid and directional control when riding their bicycles in the dirt or mud. With at least some preferred embodiments manufacturers of bicycle brakes would be able to enter the untapped retrofit market with millions of bicycles in use today with manual brakes and no antiskid system available for these vehicles. 
         [0048]    In a basic embodiment of the present invention, an antiskid system uses an actuator assembly to move a brake linkage to reduce the force that an operator is applying to a brake pad. The actuator assembly that moves the brake linkage utilizes a pulsing motion to reduce the average force that is being applied to the brake pad to reduce or eliminate tire skid. In this basic embodiment, the antiskid system also uses an electronic controller that is an On/Off switch that is actuated by the vehicle&#39;s operator to turn on the actuator assembly that pulses the manual brake linkage to reduce or eliminate tire skid. A typical application this embodiment is on a bicycle. 
         [0049]    In an advanced embodiment of the present invention, an antiskid system uses an actuator assembly that can set and hold a position of a manual brake linkage to modulate the force on a brake pad. Wheel speed sensors and optional GPS data are used by an electronic controller to detect a skidding event. When a skidding event is detected, the electronic controller automatically commands the actuator to modulate the brake force to reduce tire skid. This advanced embodiment provides more efficient antiskid protection than a basic embodiment. A typical application for the present embodiment is on GA aircraft and motorcycles. 
         [0050]      FIGS. 3A ,  3 B and  3 C are schematic diagrams showing an exemplary manual brake system for one wheel on a vehicle, in accordance with an embodiment of the present invention.  FIG. 3A  is an overall view of a simple hydraulic system with three alternate locations for a lock and release assembly and an actuator assembly, and  FIG. 3B  is a close-up view of a fourth alternate location for the lock and release assembly and the actuator assembly in the simple hydraulic system.  FIG. 3C  is an overall view of a more complex mechanical system with six alternate locations for the lock and release assembly and the actuator assembly. The present embodiment may be used on vehicles with two main wheels each with a separate brake and an independent hand or foot brake lever that is used by an operator to actuate and power the brakes. The wheels may be located in the front and rear of these vehicles such as in motorcycles and bicycles, or they may be located on the left and right side of these vehicles such as in GA aircraft. 
         [0051]    Referring to  FIG. 3A , the brake system uses the force applied to a brake lever  200  by the operator&#39;s hand or foot to create the hydraulic brake pressure. Hydraulic pressure is created by transferring the force from the operator&#39;s hand or foot to brake lever  200  to an input shaft  201  that is connected to a piston  203  in a hydraulic master cylinder  202 . Hydraulic piston  203  is contained in a cavity within master cylinder  202  in such a manner that hydraulic pressure is created in proportion to the force applied to brake lever  200  by the operator&#39;s hand or foot. A hydraulic pipe  204  connects master cylinder  202  to a hydraulic brake cylinder  111 . Hydraulic brake cylinder  111  comprises a brake piston  112  that is connected to a brake pad  113 , which is pushed against a brake disc/drum  114  creating the friction to slow the turning disc/drum  114  that is connected to a wheel  115 . This action slows and stops the vehicle. 
         [0052]    In the present embodiment, the antiskid system comprises a lock and release assembly, an actuator assembly and an electronic controller. The actuator assembly may comprise a gearmotor and pulses the brake linkage to reduce the average force on the brake pads. The lock and release assembly connects the actuator assembly to the brake linkage when the antiskid function is needed and disconnects the actuator assembly from the brake linkage when the antiskid function is not needed or if there is a loss of electrical power. There is a lock and release assembly for each actuator assembly. The actuator assembly and the lock and release assembly can be powered by the vehicle&#39;s electrical system or by a portable battery. The lock and release assembly and the actuator assembly can be located in several positions through out the manual hydraulic brake linkage system. For example without limitation, a lock and release assembly  301 A and an actuator assembly  302 A are shown mounted at brake lever  200 , a lock and release assembly  301 B and an actuator assembly  302 B are shown mounted near input shaft  201 , and a lock and release assembly  301 C and an actuator assembly  302 C are shown mounted near brake pad  113 . 
         [0053]    Referring to  FIG. 3B , a fourth exemplary location of a lock and release assembly  301 D and an actuator assembly  302 D is shown mounted in hydraulic piping  204  using a hydraulic cylinder  304 . Lock and release assembly  301 D may be located anywhere along hydraulic piping  204 . In some hydraulic brake system there is limited access to the mechanical linkage. When this is the case, a hydraulic cylinder  304  can be placed any convenient location in the brake line  204  as shown in  FIG. 3B . The shaft on the hydraulic cylinder  304  provides a mechanical linkage for connecting actuator assembly  302 D and lock and release assembly  301 D. 
         [0054]    In the present embodiment, the electronic controller used on the manual hydraulic and mechanical brake system is an On/Off Switch that is actuated by the vehicle&#39;s operator to turn on actuator assembly  302 A,  302 B,  302 C, or  302 D that pulses the manual brake linkage to reduce or eliminate tire skids. The switch also turns on lock and release assembly  301 A,  301 B,  301 C, or  301 D to connect actuator assembly  302 A,  302 B,  302 C, or  302 D to the brake linkage. A typical application for an electronic controlled antiskid system utilizing an On/Off switch is on a bicycle. 
         [0055]    In an alternate embodiment, the system comprises an actuator assembly with a gearmotor that pulses the brake linkage to reduce the average force on the brake pads without a lock and release assembly. There may be an actuator assembly for one or both wheels. The actuator assembly may be powered by the vehicle&#39;s electrical system or by a portable battery. The lock and release assembly may be eliminated when the configuration of the brake linkage enables the actuator assembly to engage and disengage the brake linkage without the need for a connection device. This is the case on some bicycle brake systems where the actuator assembly moves the scissor type brake linkages at the brake pads or when the actuator assembly moves the brake handle. When there is no lock and release assembly, a position switch is required to turn off the actuator assembly at its most refracted position. 
         [0056]    Referring to  FIG. 3C , the manual mechanical brake system for a motorcycle or bicycle is shown. These vehicles have two main wheels each with a separate brake and an independent hand or foot brake levers that are used by the operator to actuate and power the brakes. Only the brake system for the rear wheel is shown; although, there may also be a manual mechanical brake system for the front wheel on motorcycles and bicycles. 
         [0057]    In the present embodiment, the vehicle operator provides the power for the actuation of the brakes by pushing or pulling on brake lever  200  with his hand or foot. Brake lever  200  is coupled to a mechanical lever  206  with a rod or cable  205 . When the operator pushes or pulls on brake lever  200 , mechanical lever  206  pulls or pushes rod or cable  207  that is connected to a mechanical lever  208  that is connected to brake pad  113  by a rod or cable  207 . Brake pad  113  is pushed against brake disc/drum  114  creating the friction to slow the turning brake disc/drum  114  that is connected to wheel  115 . This action slows or stops the vehicle. In alternate embodiments the number and arrangement of rods, cables and levers may vary depending on the particular geometry of the vehicle. 
         [0058]    In the present embodiment, a lock and release assembly, an actuator assembly and an electronic controller is added to the manual mechanical brake system. As in the simple system, the lock and release assembly and the actuator assembly can be located in several positions through out the manual mechanical brake linkage system. For example, without limitation, a lock and release assembly  301 E and an actuator assembly  302 E are shown mounted near brake lever  200 , a lock and release assembly  301 F and an actuator assembly  302 F are shown mounted along rod or cable  205 , a lock and release assembly  301 G and an actuator assembly  302 G are shown mounted on mechanical lever  206 , a lock and release assembly  301 H and an actuator assembly  302 H are shown mounted along rod or cable  207 , a lock and release assembly  301 I and an actuator assembly  3021  are shown mounted on mechanical lever  208 , and a lock and release assembly  301 J and an actuator assembly  302 J are shown mounted near brake pad  113 . 
         [0059]    Hybrid manual brake systems exist that combine hydraulic and mechanical linkages to couple the operator&#39;s hand and/or foot movements to operate and power the brake mechanism. The brake pads in these hybrid manual brake systems can be mechanically or hydraulically actuated. In alternate embodiments the features and functions described above for the manual hydraulic and manual mechanical brake systems can be used in their respective locations in these hybrid systems. 
         [0060]      FIGS. 4A and 4B  are schematic diagrams illustrating an exemplary electronic controller for an antiskid system for manual brakes, in accordance with an embodiment of the present invention.  FIG. 4A  shows the electronic control as an On/Off switch  400 , and  FIG. 4B  shows the electronic control with the addition of a rheostat  407 . Referring to  FIG. 4A , an electricity source  401  is connected to On/Off switch  400  by an electrical cable  402 . Electricity source  401  may be various different types of electricity sources such as, but not limited to, a vehicle power source, batteries, etc. On/Off switch  400  supplies a lock and release assembly  301  and an actuator assembly  302  with electrical power through an electrical cable  403 . When an operator closes On/Off switch  400 , lock and release assembly  301  connects to the brake linkage and actuator assembly  302  pulses the brakes. When the operator opens On/Off switch  400 , actuator assembly  302  stops pulsing the brakes and lock and release assembly  301  disconnects from the brake linkage. 
         [0061]    In alternate embodiments the functionality of the electronic controller may be increased by replacing On/Off Switch  400  with other types of switches. One alternate embodiment comprises a force switch that is mounted in the brake linkage and closes when a specific brake force is reached. This turns on the actuator assembly and the lock and release assembly connecting the actuator assembly to the brake linkage. When the brake force drops below a specific level, the force switch opens and the actuator assembly stops pulsing the brakes and the lock and release assembly disconnects from the brake linkage. In this embodiment, a separate force switch is required for each actuator assembly. 
         [0062]    In another alternate embodiment, a pressure switch is mounted in the hydraulic circuit and closes when a specific brake pressure is reached. This turns on the actuator assembly and the lock and release assembly connecting the actuator assembly to the brake linkage. When the brake pressure drops below a specific level, the pressure switch opens and the actuator assembly stops pulsing the brakes and the lock and release assembly disconnects from the brake linkage. The pressure switch only works with manual hydraulic brake systems. In this embodiment, a separate pressure switch is needed for each actuator assembly. 
         [0063]    In another alternate embodiment, an inertia switch is mounted to the vehicle and closes when a specific deceleration level is reached. This switch turns on the actuator assembly and the lock and release assembly connecting the actuator assembly to the brake linkage. When the vehicle&#39;s deceleration drops below a specific level, the inertia switch opens and the actuator assembly stops pulsing the brakes and the lock and release assembly disconnects from the brake linkage. Only one inertia switch is needed for all of the actuator assemblies in this embodiment. 
         [0064]    In yet another alternate embodiment, On/Off Switch  400  is replaced with a rheostat that is actuated by the vehicle&#39;s operator in order to turn on the actuator assembly that pulses the manual brake linkage to reduce or eliminate tire skids. The rheostat enables the operator to vary the voltage, which in turn varies the frequency of the pulses from the actuator assembly. The rheostat also activates and disengages the lock and release assembly. In the present embodiment, a rheostat is need for each actuator assembly. 
         [0065]    Referring to  FIG. 4B , rheostat  407  is used in the present embodiment in combination with a switch  404 . In order to function properly with rheostat  407 , switch  404  is preferably a force switch, a pressure switch, or an inertia switch. The vehicle&#39;s operator manually controls the speed of the actuator assembly that varies the frequency of the pulses to the brake linkage using rheostat  407 . Rheostat  407  is used after switch  404  automatically turns on the actuator assembly. In the present embodiment, a rheostat is needed for each actuator assembly. 
         [0066]    In the present embodiment, the electronic controller uses On/Off switch  400  actuated by the vehicle&#39;s operator or automatic switch  404  to turn on actuator assembly  302  that pulses the manual brake linkage to reduce or eliminate tire skids. Once actuator assembly is turned on, rheostat  407  may be actuated by the operator to control the pulsing of actuator assembly  302 . Switch  400  or  404  also turns on lock and release assembly  301  to connect actuator assembly  301  to the brake linkage. A typical application for an electronic controlled antiskid system in accordance with the present embodiment is in a bicycle. 
         [0067]    Alternate embodiments of the present invention may incorporate an electronic controller that increases its functionality by incorporating a wheel speed sensor and a tone ring for each wheel that is coupled to a computing device such as, but not limited to, a smart phone by a wire or wireless connection. The tone ring and brake disc can be integrated into one assembly by making a gear shape on the inside or outside diameter of the brake disc. The wheel speed sensor and tone ring are preferably mounted outside the axle rather than inside the axle. The computing device may also comprise a GPS capability like those found on smart phones. With the use of application software, the computing device may interpret the wheel speed and compare it to the GPS ground speed calculated by the computing device. The electronic controller includes brake release switches for each wheel that enable the operator to manually turn the gearmotors in the actuator assemblies on or off to pulse the brake linkages or to stop the pulsing. Earphones located on the operator&#39;s left and right ears are connected to the computing device by wire or wireless connection. When the computing device determines that a wheel is skidding or about to skid, the computing device sends a tone to the left or right ear corresponding to the brake release switch that needs to be turned on to pulse the appropriate brake. The tone continues until the skidding stops to alert the operator to turn off the pulsing. In alternate embodiments a visual signal may be sent to the operator to warn the operator of wheel skidding, for example, without limitation, a flashing light on a control panel. In the present embodiment, the electronic controller can be powered by the vehicle&#39;s electrical system or by a portable battery. In some embodiments rheostats can be used instead of On/Off switches to vary the frequency of the pulses to the brake linkage. 
         [0068]    The embodiments described in the foregoing are directed to relatively basic implementations of an electronically controlled antiskid system for manual hydraulic and mechanical brake systems. However, the embodiments illustrated by way of example in  FIGS. 3A ,  3 B and  3 C may also be implemented as a more advanced system by incorporating an electronic controller with advanced functions. 
         [0069]      FIG. 5  is a schematic diagram of an exemplary electronic controller  500  in an electronically controlled antiskid system installed on two wheels  115  of a vehicle, in accordance with an embodiment of the present invention. In the present embodiment, the system comprises an actuator assembly  302  to set and hold a position of the brake linkage. This enables advanced electronic controller  500  to modulate the force from the brake pads on brake discs/drums  114 . Modulating the force from the brake pads is more effective at preventing tire skids than pulsing the brake pads, which is done in the foregoing embodiments. 
         [0070]    In the present embodiment, a switch is not required to actuate the antiskid system. Instead, advanced electronic controller  500  monitors the speed of wheels  115  as detected by wheel speed sensors  116  to determine if one wheel is rotating at a slower speed than the other wheel. Advanced electronic controller has electronic circuitry that can provide the electrical power for wheel speed sensors  116  and receive the wheel speed data for each wheel  115  through electric cables  118 . In alternate embodiments the advanced electronic controller may be connected to the wheel speed sensors through a wireless connection. In the present embodiment, a tone ring  117  turns with wheel  115  and creates a magnetic field disruption that can be detected by wheel speed sensors  116  to enable wheel speed sensor  116  to determine the wheel speed. In alternate embodiments, the tone ring and the brake disc/drum can be integrated into one assembly by making a gear shape on the inside or outside diameter of the brake disc/drum. In the present embodiment, wheel speed sensor  116  and tone ring  117  are mounted outside the axle. Based on the difference in wheels speeds and the rate of change of the wheel speeds, advanced electronic controller  500  determines if a skid event is occurring or about to occur. Advanced electronic controller  500  also may use an optional Global Positioning Signal (GPS) to calculate the vehicle&#39;s ground or reference speed. This feature enhances the ability of advanced electronic controller  500  to detect and control skidding events. 
         [0071]    When advanced electronic controller  500  detects a skidding event, it automatically commands a lock and release assembly  301  to connect actuator assembly  302  to the brake linkage system. Advanced electronic controller  500  then commands actuator assembly  302  to move the brake linkage a specific distance. When the brake linkage is moved, the force on the brake pads is reduced. No matter how hard the vehicle&#39;s operator pushes or pulls on the brake lever, it cannot be converted into a force on the brake pads because the brake linkage is generally prevented from moving. Once the skid is prevented, reduced or eliminated, advanced electronic controller  500  de-energizes lock and release assembly  301 , which disconnects actuator assembly  302  from the brake linkage system, and actuator assembly  302  is commanded by advanced electronic controller  500  to return to its home position. With the antiskid system in its standby mode, the manual hydraulic or mechanical brake system remains fully functional until a new skid event is detected and the antiskid process is repeated again. The antiskid system remains in standby mode as long as the antiskid function is not needed or if there is a loss of electrical power. In an alternate embodiment, an advanced electronic controller may be used to pulse the actuator assembly rather than modulating the force on the brake pads. 
         [0072]    An advantage of the advanced form of electronic controller  500  for an antiskid system for manual brakes is that electronic controller  500  can be adapted from the electronic controllers for antiskid systems for powered brakes. This includes both analog and digital controller designs that are available today. In addition, antiskid software algorithms for powered brake systems can also be adapted to be used with electronic controller  500 . Adapting current antiskid electronics and software for electronic controller  500  makes it attractive to perspective manufacturers in the antiskid business as it will reduce both the development time and cost if they are licensed to produce an antiskid system according to the present embodiment. Advanced electronic controller  500  also has the computing power to capture and annunciate faults with the antiskid system. Advanced electronic controller  500  also provides an interface connection with the antiskid control panel located at the operator&#39;s station. Advanced electronic controller  500  may be powered by the vehicle&#39;s electrical system or by a portable battery. 
         [0073]    In the present embodiment, actuator assembly  302  moves the brake linkage to reduce the force that is being applied to the brake pads and thus reduce or eliminate the tire skid. Actuator assembly  302  must have enough power to overcome the input force being applied by the operator&#39;s hand or foot. As shown by way of example in  FIGS. 3A ,  3 B and  3 C, actuator assembly  302  can be located in several locations throughout the hydraulic or mechanical brake linkage system. The power needed to overcome the mechanical leverage depends on where actuator assembly  302  is located in the brake linkage system. Actuator assembly  302  only needs to move the brake pad a small distance to reduce the force on brake disc/drum  114 . For example, without limitation, testing has shown that when actuator assembly  302  is connected to the input shaft of the master cylinder, the input shaft must only move 0.07 inches to reduce the pressure from 400 PSI to 50 PSI. 
         [0074]    Electricity is the primary source of power for actuator assembly  302 . Power may be provided from the vehicle&#39;s electrical system, the vehicle&#39;s battery, or a portable battery through advanced electronic controller  500 . Advanced electronic controller  500  is connected to lock and release assembly  301  and actuator assembly  302  through an electric cable  501 . Vehicles with manual brake systems that have an electrical system usually have a Direct Current (DC) system. Consequently, actuator assembly  302  typically uses DC electricity. However, Alternating Current (AC) electricity can also be used with actuator assembly  302  by converting the vehicle&#39;s DC electrical power to AC electrical power for the antiskid system. Actuator assembly  302  is typically driven by an electric motor; however, a hydraulic or pneumatic motor can also drive actuator assembly  302 . When a hydraulic or pneumatic motor is used, an electric motor drives a hydraulic or pneumatic pump that in turn drives the hydraulic or pneumatic motor that drives actuator assembly  302 . Power can also be provided from an accumulator or tank that contains compressed gas that can drive a hydraulic or pneumatic motor. The accumulator can directly power a hydraulic or pneumatic cylinder. The motors that drive actuator assembly  302  in most implementations use a gearbox to reduce the speed and increase the torque of the output shaft of the motor. The gearbox can be integral with the motor or can be independent from the motor. The function of actuator assembly  302  is to move the brake linkage a small distance to reduce the force on the brake pad. Therefore, the electric, hydraulic or pneumatic motors, with and without gearboxes, in some cases must convert their rotary output motion into a linear motion. 
         [0075]      FIGS. 6A through 6K  illustrate eleven different exemplary methods to drive an actuator assembly, in accordance with embodiments of the present invention.  FIG. 6A  shows a piston.  FIG. 6B  shows a bellows actuator  602 .  FIG. 6C  shows an inflatable accumulator  603 .  FIG. 6D  shows a motor  604  with a screw  606 .  FIG. 6E  shows motor  604  with helical gears  608 .  FIG. 6F  shows motor  604  with a worm gear  609 .  FIG. 6G  shows motor  604  with a gear  612  and a gear rack  613 .  FIG. 6H  shows motor  604  with scissor arms  616 .  FIG. 6I  shows motor  604  with a cam  617 .  FIG. 6J  shows motor  604  with a lever arm  619 .  FIG. 6K  shows an electric solenoid  621 . Any of these methods can be used with an electronically controlled antiskid brake system for manual brakes to drive the actuator assembly. 
         [0076]      FIGS. 6A through 6C  show three methods for converting hydraulic or pneumatic power into a linear motion. Referring to  FIG. 6A , a cylinder  600  comprises a piston inside to drive an output shaft  601  in a linear motion. Referring to  FIG. 6B , bellows actuator  602  expands or contracts with the hydraulic or pneumatic power exerted onto it to convert this power into a linear motion. Referring to  FIG. 6C , inflatable accumulator  603  converts hydraulic or pneumatic power into a linear motion in the same manner as bellows actuator  602 . 
         [0077]      FIGS. 6D through 6J  use motor  604  to drive the actuator assembly. Motor  604  can be electric, hydraulic or pneumatically powered. Motor  604  uses a gearbox  605  to reduce the speed of the output shaft and increase the torque; however, all of these methods may be implemented without a gearbox. Motor  604  turns continuously and has the ability to reverse its rotation. Motor  604  and gearbox  605  convert the rotary motion of the output shaft of motor  604  into a linear motion to move the brake linkage. Referring to  FIG. 6D , a nut  607  moves along screw  606  to convert the rotary motion of screw  606  into linear motion. Referring to  FIG. 6E , two helical gears  608  interconnect so that the rotation of one helical gear  608  translates into the linear motion of the other helical gear  608 . Referring to  FIG. 6F , worm gear  609  interconnects with a worm wheel  610  to drive a connecting rod  611  in a linear motion. Referring to  FIG. 6G , gear  612  and gear rack  613  interconnect so that the rotation of gear  612  moves gear rack  613  in a linear motion. Referring to  FIG. 6H , scissor arms  616  are connected to motor  604  with a screw  615  and a nut  614 . As screw  615  rotates, nut  614  moves along screw  615  and scissor arms  616  move up and down. Referring to  FIG. 6I , cam  617  rotates, moving a cam follower  618  in a linear motion. Referring to  FIG. 6J , lever arm  619  drives a connecting rod  620  in a linear motion. 
         [0078]    Referring to  FIG. 6K , electric solenoid  621  pulls or pushes an armature  622  with a magnetic field. Armature  622  moves the brake linkage. 
         [0079]    Those skilled in the art, in light of the present teachings, will readily recognize that a multiplicity of other suitable means may be used to drive the actuator assembly in alternate embodiments. For example, without limitation, an electric servomotor may be used to drive the actuator assembly. The servomotor utilizes an electric motor coupled to a gearbox that has an electronic sensor that monitors the rotation and position of the output shaft of the gearbox. With the use of an electronic servo controller, the output shaft of the servomotor can be commanded to rotate a specific distance and hold that position. 
         [0080]    In other non-limiting examples, the actuator assembly may utilize the independent elements described above and couple them together in various configurations. These elements can include, without limitation, combinations of electric motors, hydraulic or pneumatic pumps and motors, many different devices to convert rotary to linear motion, solenoids, hydraulic or pneumatic actuators and servomotors. These elements may also be integrated into sub-assemblies or complete assemblies to form the actuator assembly. 
         [0081]    At least some preferred embodiments of the present invention may utilize one of two types of actuator assemblies. For example, without limitation, in a basic implementation, the actuator assembly  302  pulses the brakes by moving the brake linkage back and forth a short distance at a rate of several times a second. The linear actuators described above by way of example with respect to  FIGS. 6D through 6H  can pulse the brake linkages by reversing motor  604  several times a second. If a hydraulic or pneumatic cylinder is used to pulse the brake linkage as shown by way of example in  FIGS. 6A through 6C , a control valve is needed to change the linear direction of cylinder  600 . When a cam is used to convert the rotary motion of the output shaft of motor  304  into a linear motion as shown by way of example in  FIG. 6I , motor  304  does not need to be reversed to pulse the brake linkage. Electric solenoid  621  can be used to pulse the brake linkage by turning solenoid  621  on and off. In more advanced implementations, the actuator assembly utilizes a servomotor that the electronic controller can command to move the brake linkage a specific distance and hold a position. When the brake system linkage is moved, the force on the brake pads is reduced. No matter how hard the vehicle&#39;s operator pushes or pulls on the brake lever, the force cannot be converted into a force on the brake pads because the brake system linkage is generally prevented from moving. 
         [0082]    In at least some preferred embodiments the lock and release assembly connects the actuator assembly to the brake linkage. This connection is made when the antiskid function is needed to reduce the force on the brake pads to reduce or eliminate tire skids. The lock and release assembly must have enough power to connect it to the brake linkage and support the force applied by the actuator assembly. As shown by way of example in  FIGS. 3A ,  3 B and  3 C, the lock and release assembly can be located in several locations throughout the hydraulic or mechanical brake linkage. The power required to overcome the mechanical leverage depends on where the lock and release assembly is located in the brake linkage. Testing has shown that when the actuator assembly is connected to the input shaft of the master cylinder, the lock and release assembly must support a maximum force of approximately 225 pounds, which equates to 600 PSI. This is roughly 50% more pressure than the maximum operating pressure of the manual hydraulic brake system. When the antiskid function is no longer needed, the lock and release assembly disconnects the actuator assembly from the brake linkage. This enables the normal manual brake operation to resume. On some vehicles, the release function must occur even when there is a power failure. In these cases a spring release is used that operates under the maximum load conditions. This is referred to as a fail-safe mode. 
         [0083]      FIGS. 7A through 7J  illustrate ten different exemplary methods of connecting a lock and release assembly to a brake linkage shaft  201 , in accordance with embodiments of the present invention.  FIG. 7A  shows a locking tab method.  FIG. 7B  shows a locking clamp method.  FIG. 7C  shows a wire lock method.  FIG. 7D  shows a tapered wedge method.  FIG. 7E  shows a dual cam lock method.  FIG. 7F  shows a strap clamp method.  FIG. 7G  shows a locking collar method.  FIG. 7H  shows an external fork method.  FIG. 7I  shows an iron particle method, and  FIG. 7J  shows a hydraulic piston method. Referring to  FIG. 7A , a hole in a locking tab  700  connects locking tab  700  to brake linkage shaft  201  when one end of locking tab  700  is moved in a parallel direction to brake linkage shaft  201 . The diameter of the hole is slightly larger than brake linkage shaft  201 . The thickness of locking tab  700  is preferably sized to create enough locking force while providing enough material not to deform under load. A pivot edge  701  partially establishes the force that is required to release locking tab  700 . Varying the distance from brake linkage shaft  201  to pivot edge  701  changes the force required to release locking tab  700 . 
         [0084]    Referring to  FIG. 7B , two jaws made of metal or other high strength material connect to brake linkage shaft  201  when the jaws are moved towards each other to create a locking clamp  702 . A pivot point  703  located close to brake linkage shaft  201  creates additional leverage when the other end of the jaws of locking clamp  702  are brought together. 
         [0085]    Referring to  FIG. 7C , a wire lock  704  is created by wrapping a coil of wire around brake linkage shaft  201  and pulling tightly on both ends of the wire. Referring to  FIG. 7D , a tapered wedge  705  is inserted into a tapered groove  706  to make a firm connection with brake linkage shaft  201 . Referring to  FIG. 7E , a dual cam lock  707  firmly connects to brake linkage shaft  201  when the cams are rotated. Referring to  FIG. 7F , the ends of a strap  708  are pulled tight in relation to a support collar  709  to connect to brake linkage shaft  201 . Referring to  FIG. 7G , a locking collar  711  is connected to brake linkage shaft  201  by inflating a ring  710  with air or fluid. 
         [0086]    Referring to  FIG. 7H , a tapered fork  712  is placed over the outside diameter of brake linkage shaft  201 . The outside diameter of brake linkage shaft  210  and the inside surface of tapered fork  712  may have matching grooves  713  to increase the integrity of the connection. 
         [0087]    Referring to  FIG. 7I , brake linkage shaft  201  comprises a piston  715  attached to brake linkage shaft  201  inside a cylinder  719 . Also inside cylinder  719  are iron particles  714  that become rigid when electrified. When iron particles  714  are electrified, cylinder  719  locks to piston  715  and brake linkage shaft  201 . 
         [0088]    Referring to  FIG. 7J , a hydraulic piston  716  connects to brake linkage shaft  201 . This is done by preventing hydraulic fluid  720  from flowing freely in interconnected pipes  717  when a valve  718  is closed. Piston  716  connected to brake linkage shaft  210  is unable to move when fluid  720  is locked in place. 
         [0089]    Those skilled in the art, in light of the present teachings, will readily recognize that a multiplicity of different suitable means may be used to connect the lock and release assembly the brake linkage, which enables the actuator assembly to move the brake linkage and reduce the force on the brake pads. 
         [0090]    The lock and release assembly in at least some preferred embodiments requires an actuator to connect and disconnect it from the brake linkage. Electricity is the primary source of power for the lock and release assembly. Power may be provided from the vehicle&#39;s electrical system, the vehicle&#39;s battery, or a portable battery. Vehicles with manual brake systems that have an electrical system typically have a Direct Current (DC) system. Therefore, the lock and release assembly normally uses DC electricity. However, alternating current (AC) electricity can also be utilized to power the lock and release assembly. The lock and release assembly can be driven by an electric motor. A hydraulic or pneumatic motor can also drive the lock and release assembly. When a hydraulic or pneumatic motor is used, an electric motor drives a hydraulic or pneumatic pump that in turn drives the hydraulic or pneumatic motor that drives the lock and release assembly. Power can also be provided from an accumulator or tank that contains compressed gas that can drive a hydraulic or pneumatic motor. The accumulator can also directly power a hydraulic or pneumatic cylinder to operate the lock and release assembly. 
         [0091]    When motors are used to drive the lock and release assembly, the motors in most cases use a gearbox to reduce the speed and increase the torque of the output shaft of the motor. The gearbox can be integral with the motor or it can be independent from the motor. The lock and release assembly may use an electric, hydraulic or pneumatic motor, with or without a gearbox, and in some cases the rotary output motion of the motor must be converted into a linear motion.  FIGS. 6D through 6J  illustrate seven exemplary methods for converting the rotary motion of the output shaft of a motor or gearbox to a linear motion. Any of these methods or other methods may be used with the lock and release assembly to convert the rotary motion of a motor or gearbox to a linear motion to move the brake linkage. For example, without limitation, when a hydraulic or pneumatic source of power is available, a hydraulic or pneumatic cylinder can be used to operate the lock and release assembly. These cylinders can utilize a piston, bellows or inflatable bag to convert the hydraulic or pneumatic energy into a linear motion, as shown by way of example in  FIGS. 6A through 6C . An electric solenoid can also be used to operate the lock and release assembly by applying electrical power to a coil, which moves an armature with its magnetic field to move the lock and release assembly, as illustrated by way of example in  FIG. 6K . The lock and release assembly can utilize the independent elements described above and couple them together in various different combinations. These elements may include, without limitation, combinations of electric motors, hydraulic or pneumatic pumps and motors, many different devices to convert rotary to linear motion, solenoids, hydraulic or pneumatic actuators and servomotors. These elements can also be integrated into sub-assemblies or complete assemblies to form the lock and release assembly. 
         [0092]    As described in foregoing, there are many methods for incorporating the lock and release assembly and the actuator assembly for an electronically controlled antiskid system for vehicles with manual brakes in accordance with at least some preferred embodiments of the present invention. The following description outlines a preferred method of incorporating the lock and release assembly and the actuator assembly in a manual hydraulic brake system. On manual hydraulic brake systems, the master cylinder, the lock and release assembly and the actuator assembly can be combined into an integrated package that is referred to herein as an electric master cylinder (EMC). The master cylinder in the integrated package maintains the same geometry and retains the same functions as the manual master cylinder that has been certified for the vehicle. This enables the original manual brake system to remain certified and fully functional when the electronic controlled antiskid system is not operating. 
         [0093]      FIG. 8  is a side view of an exemplary electric master cylinder (EMC) with an integrated actuator assembly  302 , in accordance with an embodiment of the present invention. In the present embodiment, the EMC comprises a motor  800  to control the movements of an input shaft  201 . Motor  800  in the EMC may one of two different types of electrical motors. The first type is a servomotor that supports an advanced implementation because the servomotor can rotate an output shaft  802  to a specific position as directed by an electronic controller. This controls the distance that input shaft  201  moves, giving the system the ability to modulate the hydraulic brake pressure. This pressure modulation feature increases the efficiency of the antiskid system. 
         [0094]    The second type of motor that can be used on the EMC is a gearmotor. When energized, the gearmotor rotates continuously. This in turn rotates a cam  803  continuously raising and lowering input shaft  201  a set distance. The gearmotor “pulses” the brakes to reduce tire skidding. Because the hydraulic brake pressure cannot be modulated, the gearmotor configuration is a less efficient antiskid system compared to the servomotor configuration. A position switch is required to stop the gearmotor when the cam is in its lowest position. 
         [0095]    In the present embodiment, electric motor  800  is attached to a master cylinder  202 . Attached to output shaft  802  of motor  800  is a drive train  804 . Drive train  804  couples output shaft  802  of motor  800  to cam  803 . Several different types of drive trains can be used such as, but not limited to, gears (as shown), sprockets and chain, belts and pulleys, etc. Any of these drive trains may be used with either a servomotor or a gearmotor. In addition, the servomotor can use a push/pull rod to connect output shaft  802  to cam  803  because the output shaft of a servomotor only rotates approximately  90  degrees. 
         [0096]    One end of drive train  804  is centrally located about output shaft  802  of motor  800  and the other end is centrally located about input shaft  201  of master cylinder  202 . Mounted under cam  803  is a thrust bearing  805 . Thrust bearing  805  reduces the friction and torque in drive train  804  from the force applied to input shaft  201  from a brake lever by an operator&#39;s hand or foot. Attached to drive train  804  and located at input shaft  201  is cam  803 . Cam  803  uses ramps to raise and lower cam followers  806  when drive train  804  is rotated by motor  800 . Cam  803  has one ramp for each cam follower  806 . The slope of the ramps determines the rate and amount of modulation or pulsing on the brake system&#39;s hydraulic pressure. In the present embodiment, actuator assembly  302  comprises motor  800 , output shaft  802 , cam  803 , drive train  804 , and thrust bearing  805 , and these items can be located radially in any position about input shaft  201  to create a compact design to facilitate the retrofit replacement of the manual master cylinder  202  with the integrated EMC in the vehicle. 
         [0097]    In the present embodiment, a lock and release assembly  301  is also integrated into the EMC. Lock and release assembly  301  comprises cam followers  806  an electric lock solenoid  807 , a mounting block  808 , axles  809 , a pivot edge  810 , a lock tab  811 , a lock solenoid armature  812 , a nut  813 , a washer  814  a release spring  815 , a fastener  816 , and anti-rotation ears  817 . Lock and release assembly  301  can be located radially in any position about input shaft  201  to create a compact design to facilitate the retrofit replacement of the manual master cylinder  202  with the EMC. Lock and release assembly  301  connects actuator assembly  302  to input shaft  201  when there is a skidding situation. Electric lock solenoid  807  is energized by the electronic controller when lock and release assembly  301  needs to connect to input shaft  201  when the brake pressure must be lowered to generally prevent, reduce or eliminate a tire skid. The electrically actuated lock solenoid  807  is used in the present embodiment so that, if there is a loss of electrical power, the antiskid system automatically disconnects from input shaft  201  and the manual brake system remains fully operational. However, in alternate embodiments the lock and release assembly may use other connection means such as, but not limited to, those shown by way of example in  FIGS. 6A through 6J . In the present embodiment, lock and release assembly  301  is integrated with manual master cylinder  202  and is centrally located about input shaft  201  of master cylinder  202 . Lock and release assembly  301  comprises at least two cam followers  806  equally spaced around input shaft  201 . Multiple cam followers  806  are needed to generally prevent side loading of input shaft  201  when cam  803  is rotated and input shaft  201  is raised and lowered. Cam followers  806  ride on the ramps of cam  803 . When cam  803  is rotated by motor drive assembly  804 , cam followers  806  are raised and lowered by rolling up and down the ramps of cam  803 . 
         [0098]    A mounting block  808  is required to secure cam followers  806  and lock solenoid  807  together as a single unit. Mounting block  808  has a vertical hole through it that centrally locates it about input shaft  201 . Rocking of mounting block  808  about input shaft  201  is preferably minimized by having a close tolerance hole for input shaft  201  with a sufficient length to diameter ratio. Protruding from mounting block  808  are axles  809 , which are used to attach cam followers  806  to mounting block  808 . Mounting block  808  comprises pivot edge  810  located a short distance from input shaft  201 . This distance partially determines the lock and release loads for lock tab  811 . Also attached to mounting block  808  is lock solenoid  807 . Lock tab  811  comprises a hole that centrally locates lock tab  811  about input shaft  201 . The diameter and thickness of the hole are sized to create the necessary lock and release loads of lock tab  811 . Lock tab  811  comprises a feature at one end to facilitate the attachment of lock solenoid armature  812 . In the present embodiment, lock solenoid  807  is attached to mounting block  808  in such a way that lock solenoid  807  can be adjusted vertically to create the desired pull force with lock solenoid armature  812 , which is attached to lock tab  811 . When electrical power is applied to lock solenoid  807 , a magnetic force is created that pulls lock solenoid armature  812  into lock solenoid  807 . This pulls lock tab  811  towards lock solenoid  807 , which secures lock tab  811  to input shaft  201 . 
         [0099]    A hold down spring  819  is centrally located about input shaft  201 . Hold down spring  819  is retained on input shaft  201  with nut  813  and washer  814 . Hold down spring  819  generally ensures that lock tab  811  remains seated against pivot edge  810  in both the locked and released modes of operation. Hold down spring  819  also generally ensures that lock and release assembly  301  returns to its lowest position when lock solenoid  807  is de-energized. Release spring  815  located between solenoid mounting block  808  and lock tab  811  generally ensures that lock tab  811  releases from input shaft  201  when lock solenoid  807  is de-energized. Release spring  815  is retained in the proper position by placing it over lock solenoid armature  812 . Release spring  815  provides a fail-safe mode when used in conjunction with electric solenoid  807 . The movement of lock tab  811  is restricted by fastener  816 . Anti-rotation ears  817  are part of master cylinder  202  and generally prevent lock and release assembly  301  from rotating about input shaft  201  when the actuator assembly  302  is operating. 
         [0100]    In some embodiments the hydraulic cylinder, shown by way of example in  FIG. 3B , may use the same elements of the EMC to create an integrated package combining the hydraulic cylinder  304 , the lock and release assembly  301  and the actuator assembly  302 . 
         [0101]    Testing of a prototype EMC has shown that  38  watts of electrical power is used to operate both lock and release assembly  301  and actuator assembly  302 . This level of power consumption is achieved at a proof pressure of 600 PSI, which is 50% higher than the maximum operating pressure of master cylinder  202 . Actuator assembly  302  and lock and release assembly  301  work against a force on input shaft  201  of 225 pounds to attain the 600 PSI of brake pressure. Testing of the prototype EMC has also revealed that hydraulic brake pressure may be modulated at a rate of 1000 PSI per second and the pressure may be set within 10 PSI using a servomotor. The total weight for lock and release assembly  301  and actuator assembly  302  in the present embodiment is less than one pound. 
         [0102]    In at least some preferred embodiments, the function of a wheel speed sensor is to provide a signal to an electronic controller that can be used to determine the speed that the wheel is turning. There are two types of wheel speed sensors that can be used in an electronically controlled antiskid system for vehicles with manual brakes. The first type is a variable-reluctance sensor. The disadvantage of the variable-reluctance sensor is the decreasing signal strength as the wheel rotation slows. This means that the antiskid function cannot operate below a vehicle speed of approximately 10 miles per hour due to an insufficient signal from the wheel speed sensor. The second type of wheel speed sensor is an active or magneto-resistive sensor. This type of sensor cannot generate a signal on its own and needs input power from the electronic controller to operate. However, an advantage of the magneto-resistive type of wheel speed sensor is that it can operate down to zero wheel speed. This means the antiskid function can work down to zero vehicle speed making the antiskid function available during both high and low speeds. 
         [0103]      FIG. 9  is a side view of an exemplary wheel speed sensor  116  attached to a brake caliper  900  located on a main wheel  115 , in accordance with an embodiment of the present invention. In the present embodiment, wheel speed sensor  116  is connected to brake caliper  900  using a bracket  901 . Bracket  901  can be an integral part of brake caliper  900  or it can be a separate item that is attached to brake caliper  900 . An electrical cable  118  with suitable conductors and shielding transmits electrical power from an electronic controller to wheel speed sensor  116 . The same electrical cable  118  transmits the wheel speed signal from sensor  116  to the electronic controller. 
         [0104]    The variable-reluctance and magneto-resistive types of wheel speed sensors both require a gear-shaped tone ring to operate. When the tone ring rotates near a wheel speed sensor of either type, a magnetic field fluctuates around the sensor. The electronic controller interprets the voltage and frequency variation sent from sensor  116  and converts this information into a speed of rotation of wheel  115 . In the present embodiment, the tone ring is incorporated into a brake disc  902  by cutting a gear shape into the outside circumference of brake disc  902 . This enables brake disc  902  to perform the function of a tone ring. In alternate embodiments the gear shape may be cut into the inside diameter of the brake disc. In the present embodiment, wheel speed sensor  116 , attached to brake caliper  900 , and brake disc  902 , which functions as a tone ring, are externally mounted to the axle of wheel  115 . 
         [0105]    Having fully described at least one embodiment of the present invention, other equivalent or alternative methods of providing an electronically controlled antiskid braking system for vehicles with manual brakes according to the present invention will be apparent to those skilled in the art. The invention has been described above by way of illustration, and the specific embodiments disclosed are not intended to limit the invention to the particular forms disclosed. For example, the particular implementation of the antiskid system may vary depending upon the particular type of vehicle used. The vehicles described in the foregoing were directed to two wheeled implementations; however, similar techniques are to provide antiskid systems for vehicles with manual brakes that have fewer or more wheels such as, but not limited to, unicycles, tricycles, three wheeled motorcycles, all terrain vehicles (ATVs), etc. Non-two wheeled implementations of the present invention are contemplated as within the scope of the present invention. The invention is thus to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the following claims. 
         [0106]    Claim elements and steps herein have been numbered and/or lettered solely as an aid in readability and understanding. As such, the numbering and lettering in itself is not intended to and should not be taken to indicate the ordering of elements and/or steps in the claims.