Abstract:
A system and method for providing a haptic device in a vehicle. The system comprises a foot operated pedal of a vehicle. A sensor is coupled to the pedal and is configured to sense a position of the pedal during use. The sensor is configured to output a sensor signal associated with the position of the pedal. A processor is coupled to the sensor and is configured to receive the sensor signal. The processor outputs a control signal upon the pedal moving past a threshold position. An actuator is coupled to the processor, wherein the actuator is configured to output a haptic feedback force to the pedal upon receiving the control signal from the processor.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation of U.S. patent application Ser. No. 11/493,858, filed Jul. 25, 2006 which is a continuation of U.S. patent application Ser. No. 10/975,051, filed Oct. 28, 2004, now U.S. Pat. No. 7,096,852 which claims the benefit of U.S. Provisional Patent Application Ser. No. 60/516,187, filed on Oct. 30, 2003, entitled “Self-Regulating Resistive Actuator For Automotive Throttle Pedal Force Feedback,” commonly owned herewith. 
    
    
     BACKGROUND 
     The present relates generally to haptic feedback systems, and more particularly, to a haptic feedback system associated with an automotive throttle actuator. 
     Control of a vehicle through the use of electronically-controlled mechanisms rather than mechanically-controlled mechanisms has been implemented in different forms. Typically called “steer-by-wire,” “drive-by-wire,” or “control-by-wire,” electronically-controlled mechanisms direct electric motors and/or hydraulic or pneumatic control systems, to perform mechanical operations rather than a user directly performing the mechanical operations using a mechanical interface. For example, in a standard mechanical steering system in an automobile, the user moves a steering wheel, which mechanically rotates rods, gears, and other mechanical elements to turn the front wheels based on the motion of the steering wheel. In a drive-by-wire system, the user rotates the steering wheel (or moves some other type of manipulandum) to generate control signals to control one or more electric motors, hydraulic actuators, etc., which turn the front wheels. No mechanical linkage between steering wheel motion and wheel motion exists (unlike power assisted steering). A processor (microprocessor, etc.) can be used to sense motion of the steering wheel and correlate it with motor control to achieve the corresponding steering of the wheels. 
     Another vehicle control system that is typically now electronically-controlled rather than mechanically-controlled is the vehicle throttle control. Automotive throttle pedals historically provided a characteristic force against a driver&#39;s foot as a function of pedal displacement. In the past, this force was associated with mechanical linkages and a cable connecting the throttle pedal to the throttle valve in the engine. Rather than direct pedal control of throttle position, newer Electronic Throttle Control (ETC) systems use servo-valves. 
     In ETC systems, the throttle pedal provides only a sensor input to the ETC and, in the absence of the inherent friction associated with traditional mechanical throttle valve linkages, the characteristic force feedback to the driver must be recreated by other means. The force profile associated with known throttle control generally includes an increasing reaction force against the driver&#39;s foot the farther the pedal is depressed. This increased physical effort applied by the driver is consistent with the increased effort associated with the vehicle to achieve the desired acceleration. 
     Known mechanical systems that reproduce and/or simulate the necessary friction, however, are not ideal due to variation in the friction output associated with various parameters including system component inconsistencies, mechanical wear of system components, and variation in operating environment (e.g., temperature, humidity, atmospheric pressure, etc.). 
     A need exists for improvements in feedback to throttle controls using throttle-by-wire systems to produce desired haptic effects. 
     OVERVIEW 
     A system and method for providing a haptic device in a vehicle. The system comprises a foot operated pedal of a vehicle. A sensor is coupled to the pedal and is configured to sense a position of the pedal during use. The sensor is configured to output a sensor signal associated with the position of the pedal. A processor is coupled to the sensor and is configured to receive the sensor signal. The processor outputs a control signal upon the pedal moving past a threshold position. An actuator is coupled to the processor, wherein the actuator is configured to output a haptic feedback force to the pedal upon receiving the control signal from the processor. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic representation of a haptic throttle device according to an embodiment. 
         FIG. 2  is a schematic representation of a haptic throttle device according to another embodiment. 
         FIG. 3  is a schematic representation of a haptic throttle device according to a further embodiment. 
         FIG. 4  is a graph illustrating an example of a relationship between force feedback provided to a throttle interface and the position of the throttle interface according to an embodiment. 
         FIG. 5  is a graph illustrating an example of force feedback provided to the interface device of  FIG. 2  over a period of time according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     An apparatus is disclosed that includes a sensor configured to be coupled to a throttle interface. The sensor is configured to output a sensor signal associated with a condition of the throttle interface. A first brake element has a first friction surface, and a second brake element has a second friction surface. The second brake element is configured to be coupled to the throttle interface. The friction surface associated with the first brake element is positioned opposite the friction surface associated with the second brake element. The first brake element is configured to move relative to the second brake element. An actuator is coupled to the first brake element and is configured to output haptic feedback to the throttle interface via the first brake element based on the sensor signal. 
     In other embodiments, a method includes receiving a first input signal from a throttle interface and outputting a sensor signal associated with the input signal, the sensor signal being associated with the first input signal. Haptic feedback associated with the sensor signal is output via an actuator. A second input signal is received at a processor, the second input signal being associated with information independent of an operation of the throttle interface. Haptic feedback associated with the second input signal is output. 
     A related control-by-wire embodiment is “shift-by-wire,” in which an automobile or other vehicle having a driving transmission is shifted through its transmission gears using electronic control rather than direct mechanical control. Thus, instead of the user moving a shift lever to predetermined mechanical positions to mechanically change gears, the user can manipulate an electronic control and the electronic system can change the actual transmission gears. A shift-by-wire system is disclosed in U.S. patent application Ser. No. 10/116,237 now U.S. Pat. No. 6,904,823. 
     Referring to  FIG. 1 , a schematic illustration of a haptic throttle device is illustrated. The haptic throttle device  10  includes a throttle interface  20 . A sensor  30  is configured to output a sensor signal associated with a condition of the throttle interface  20 . For example, sensor  30  can be a position sensor configured to measure a relative or absolute position of the throttle interface, a strain gauge to measure a strain associated with input received from the throttle interface, and/or a force sensor configured to measure a magnitude of a force input from the throttle interface  20 . 
     Sensor  30  can include, for example, optical encoders that provide signals to measure the movement of the throttle interface  20 . Other types of sensors can also be used such as, for example, a potentiometer, a Hall effect sensor, a resolver, a load cell, a force sensitive resistor, a MEMS micro strain sensor, a resistive sensor, a piezoelectric sensor, a Linear Variable Displacement Transducer (LVDT), a Rotational Variable Displacement Transformer (RVDT), a capacitive sensor, or other analog or digital sensor. The sensor  30  can be an absolute or relative sensor. 
     The signal output from the sensor  30  is transmitted to a processor  40 . In some embodiments, the processor includes a processor readable medium. The processor  40  is configured to receive signals from the sensor  30  and output signals to an actuator  50 . In some embodiments, the processor  40  can receive and process signals associated with information independent of an operation of the throttle interface. For example, the processor  40  can receive signals from peripheral devices and/or systems  60  as will be discussed below. 
     The processor  40 , according to some embodiments, can be a commercially available microprocessor or combination of microprocessors. Alternatively, the processor  40  can be an application-specific integrated circuit (ASIC) or a combination of ASICs, which are designed to achieve one or more specific functions, or enable one or more specific devices or applications. In yet another embodiment, the processor  40  can be an analog or digital circuit, or a combination of multiple circuits. 
     In some embodiments, the processor  40  includes or is coupled to the processor readable medium. The processor readable medium can include, for example, one or more types of memory. For example, the processor readable medium can include a read only memory (ROM) component and a random access memory (RAM) component. The processor readable medium can also include other types of memory that are suitable for storing data in a form retrievable by the processor  40 . For example, electronically programmable read only memory (EPROM), erasable electronically programmable read only memory (EEPROM), flash memory, as well as other suitable forms of memory can be included within the processor readable medium. The processor  40  can also include a variety of other components, such as for example, co-processors, graphics processors, etc., depending upon the desired functionality of the interface device  10 . 
     The processor  40  can store data in the processor readable medium or retrieve data previously stored in the processor readable medium. The components of the processor  40  can communicate with peripheral devices  60  external to the processor  40  by way of an input/output (I/O) component (not shown). According to some embodiments, the I/O component can include a variety of suitable communication interfaces. For example, the I/O component can include, for example, wired connections, such as standard serial ports, parallel ports, universal serial bus (USB) ports, S-video ports, local area network (LAN) ports, small computer system interface (SCSI) ports, and so forth. Additionally, the I/O component can include, for example, wireless connections, such as infrared ports, optical ports, Bluetooth® wireless ports, wireless LAN ports, or the like. 
     The actuator  50  is configured to output haptic feedback to the throttle interface  10  based on at least the sensor signal. The actuator  50  is configured to simulate friction that would be output by known gear and cable throttle systems. The actuator  50  can be for example, an electromagnetic actuator such as a solenoid, a voice coil, a DC motor, a linear actuator, a moving magnet actuator, a piezoelectric actuator, an electroactive polymer (EAP), a resistive actuator (e.g., a brake), a pneumatic actuator, etc. As will be discussed in greater detail, passive actuators, such as brakes, output a resistance to inhibit motion of the throttle interface, rather than outputting an active force on the throttle interface independently of the input as with active actuators. In some embodiments, the actuator  50  can include more than one actuator. 
     Referring to  FIG. 2 , in another embodiment, a device  100  includes a throttle interface  200 , a sensor  300 , an actuator assembly  500  and a processor or controller  400 . The actuator assembly  500  includes a brake element  510  that has a friction surface  511 , and a brake element  520  that has a friction surface  521 . The friction surfaces  511 ,  521  can be, for example, metal (coated or uncoated), asbestos or other fibrous material, and/or a bushing material (e.g., sintered bronze and/or hard plastic). The friction surfaces  511 ,  521  need not include the same materials. A film or coating (not shown), a lubricant, or other fluid can be disposed between the friction surfaces  511 ,  521  (e.g., lubricating oil or grease, or dry film lubrication including mineral oil, natural or synthetic lubricants, molybdenum disulfide, PTFE, graphite, etc.) to enhance or control friction, mechanical wear or other desired properties. 
     The brake element  520  is coupled to the throttle interface  200 . The friction surface  511  associated with the brake element  510  is positioned opposite the friction surface  521  associated with the brake element  520 . The brake element  510  is configured to move relative to the brake element  520 . For example, the brake element  510  and brake element  520  can be parallel plates that move with respect to each other in a linear or rotary direction. An actuator  550  is coupled to the brake element  510  and is configured to output haptic feedback to the throttle interface  200  via the brake elements  510 ,  520  based on a sensor signal received from the sensor  300 . The components of actuator assembly  500  can be mounted to a housing  250  or some other mechanical ground (e.g., a vehicle body in which the device  100  is disposed). For example, brake elements  510 ,  520  can be coupled, either directly or indirectly, to the housing  250 . 
     The actuator  550  is configured to output a force substantially normal to the brake element  510  and the brake element  520 . The force output by the actuator  550  causes a friction force between the friction surface  511  and the friction surface  521 . For example, the actuator  550  can be a voice coil-type actuator and can urge the brake element  510  towards the brake element  520  to cause the friction surfaces  511 ,  521  to move together, thereby resulting in a friction force as the brake element  520  moves with respect to brake element  510 . Depending upon the magnitude of the force output by the actuator  550 , the resulting friction force will be modified. As illustrated in  FIG. 2 , the brake element  520  is coupled to the throttle interface  200 . When a force is input to the throttle interface  200  by a user, the brake element  520  moves with respect to the brake element  510 . Depending upon the friction force that is applied, the haptic feedback felt by the user will vary. For example, as the throttle interface  200  is depressed by a user, the further the throttle interface  200  is depressed, the greater the magnitude of the haptic feedback output. 
     The processor  400  is configured to receive signals from the sensor  300  associated with inputs from the throttle interface  200 . The processor  400  defines the control signal output to the actuator to modify the haptic feedback output to the throttle interface  200 . In some embodiments, the processor  400  receives input signals from peripheral devices  600 . For example, the peripheral devices  600  can include, for example, vehicle control systems such as the transmission, engine control systems, cruise control systems, driver preference systems such as climate control, weather sensing systems, vehicle fluid sensing systems, etc. 
     A graph illustrating an example of a relationship between the magnitude of the force feedback provided to the throttle interface  200  and the position of the throttle interface is shown in  FIG. 4 . Although not illustrated in  FIG. 4 , it is understood that when the position of the throttle interface  200  is maintained constant over time, the magnitude of the force feedback provided to the throttle interface is substantially constant. 
     In some embodiments, the processor  400  can receive a signal associated with peripheral devices  600  and indicating, for example, that a predetermined threshold has been reached with respect to vehicle speed or engine RPM, or that the vehicle is approaching a barrier, etc. In such a situation, the actuator  550  can cause an increase in the friction force between the friction surfaces  511 ,  521  to prevent the throttle interface  200  from being pushed further. 
     Other peripheral devices  600  from which the processor  400  can receive signals include, for example, a wireless device such as a mobile phone, a Personal Digital Assistant (PDA), a radio, a CD player, and MP3 player, etc. In some embodiments, the processor  400  can receive signals from external sensors that detect allowable speed limits, global position, etc. 
       FIG. 5  is a graph illustrating an example of the magnitude of the force feedback provided to the interface device  200  over a period of time. Haptic effects  900  are output at certain times based on sensor signals received from peripheral devices  600 . The illustrated haptic effects  900  are provided by way of example only. As discussed below, any haptic effect can be output based on the sensor signal. As a result of the output of haptic effects  900 , the user engaging the throttle will receive a particular feedback depending upon the peripheral device  600  with which the particular signal is associated. 
     In some embodiments, compliant element  700 , such as a mechanical spring, is coupled between the throttle interface  200  and the housing  250 . The compliant element  700  is configured to provide further resistance against movement of the throttle interface to simulate known mechanical throttle assemblies. 
     In some embodiments, the actuator assembly  500  includes a compliant element  750  that biases the brake elements  510 ,  520  together to generate a preset amount of force between the friction surfaces  511 ,  521 . The compliant element  750  can be coupled in series and/or in parallel with the actuator  550 . The compliant element  750  generates a substantially fixed amount of force, while the actuator  550  is configured to provide a variable amount of force as discussed above. This configuration allows the actuator assembly  550  to regulate the amount of force output to the throttle interface  200 . 
     In some embodiments, an actuator device  100 ′ includes a throttle interface  200 ′, a throttle condition sensor  300 ′ and an actuator assembly  500 ′ as illustrated in  FIG. 3 . The actuator assembly  500 ′ includes a compliant element  700 ′ coupled to the throttle interface  200 ′ and a housing  250 ′; a resistive actuator  550 ′ coupled to the throttle interface  200 ′ and the housing  250 ′; and an active actuator  580  coupled to the throttle interface  200 ′ and the housing  250 ′. A processor  400 ′ is coupled to the resistive actuator  550 ′ and the active actuator  580  and is configured to receive signals from the sensor  300 ′ and output control signals to the active actuator  580  and the resistive actuator  550 ′. 
     The active actuator  580  actively provides a controllable amount of force to the throttle interface  200 ′ in addition to the controllable amount of force resistively provided by the resistive actuator  550 ′. The active actuator  580  actively pushes the throttle interface  200 ′ based on input signals received from processor  400 ′, which in turn is based on signals received from sensor  300 ′ and peripheral inputs  600 ′. 
     A number of force sensations can be output via the actuators such as actuators  50 ,  550 ,  550 ′,  580 . Force effects output on the throttle interface  200 ,  200 ′ can include, for example, springs, dampers, textures, vibrations, detents, jolts or pulses, inertia, friction, obstructions (barriers), or dynamic force effects. Many of these effects are described in U.S. Pat. Nos. 5,734,373; 6,147,674; 6,154,201; and 6,128,006. 
     While various embodiments have been described above, it should be understood that they have been presented by way of example only, and not limitation. Thus, the breadth and scope should not be limited by any of the above-described embodiments, but should be defined only in accordance with the following claims and their equivalents. 
     The previous description of the embodiments is provided to enable any person skilled in the art to make or use the system. While the embodiments have been particularly shown and described with reference to embodiments thereof, it will be understood by those skilled in art that various changes in form and details may be made therein without departing from the spirit and scope of the claims. 
     For example, although the above embodiments are described as including only one sensor, in alternative embodiments any number of sensors may be used to detect various conditions of the throttle interface and or various vehicle conditions. 
     Although the above embodiments are described as receiving signals from peripheral devices at a processor, in alternative embodiments the haptic throttle device can include local sensors that are configured to actively detect various conditions of peripheral devices. 
     Although the actuator  550  is described above as being configured to output a force substantially normal to the brake element  510  and the brake element  520 , in alternative embodiments, the force need not be normal to the brake elements  510 ,  520 .