Patent Application
20140316661
This disclosure relates to a seat system for a vehicle. In an X, Y, Z coordinate system, a person can be subject to motion in six degrees of freedom. These degrees of freedom include rotation about the X, Y and Z axes, and translation substantially parallel to each of these axes. When traveling in a vehicle such as a farm tractor or a car, a person can be quite sensitive to vehicle rotations about roll and pitch axes. As such, passengers in vehicles with relatively stiff suspensions (e.g. farm tractors, sports cars) can be made uncomfortable when the vehicle starts rocking side-to-side and/or pitching back and forth due to an uneven surface over which the vehicle is traveling.
U.S. Pat. No. 5,857,535 discloses a low aspect self-propelled vehicle (1) operated by a driver (4) sitting on top of it, has its seat (7) supported from beneath by a flange (12) which is pivoted to tilt about a horizontal axis (15) in the mid-vertical plane of the vehicle. The spacing between the axis (15) and the seat (7) is sufficient to ensure that when the seat is tilted about the axis by operation of a tilt control mechanism (21), the center of seat also displaces a significant extent in the uphill direction of the slope. This reduces the downhill movement of the center-of-gravity (10) of the combination of vehicle plus driver, so that the risk of the vehicle toppling is reduced.
In one aspect, a seat system for a vehicle includes a seat including a seat bottom on which a person can sit. A first imaginary reference vertical centerline passes through a body of a person who is sitting in the seat when both the seat and the vehicle are in a nominal, level horizontal orientation. An intermediate support structure is secured to the seat and the vehicle which allows the seat to move relative to the vehicle. A first actuator can interact with the seat to cause the seat to move relative to the vehicle. One or more sensors can each measure an aspect of motion. A processor can (i) receive input from each of the one or more sensors, and (ii) utilize the input to determine a desired movement of the seat relative to the vehicle such that a combined motion of the seat relative to the vehicle and the vehicle relative to earth results in motion of the person about a virtual pivot point located substantially along the reference vertical centerline.
Embodiments may include one or more of the following features. The motion of the vehicle relative to earth is a rotation of the vehicle about an axis. The virtual pivot point is located above the axis about which the vehicle is rotating. The virtual pivot point is located above a floor of the vehicle. The virtual pivot point is located above a level where relative motion of the seat with respect to the vehicle occurs. The processor controls motion of the seat in order to minimize displacement of the virtual pivot point along the reference vertical centerline as the vehicle is rotated. The virtual pivot point is located about 1-4 feet above a surface of the seat bottom on which the person can sit. The virtual pivot point is located about 2-3 feet above a surface of the seat bottom on which the person can sit. The seat is pivotally connected to the vehicle at or near a floor of the vehicle. The actuator causes the seat to rotate about a second axis in an opposite sense relative to the rotation of the vehicle about the first axis. The seat is able to rotate about a second axis which is non-intersecting with a horizontal plane. The second axis is substantially parallel to a direction in which the vehicle is moving when the vehicle is traveling in a straight line. The second axis is substantially perpendicular to a direction in which the vehicle is moving when the vehicle is traveling in a straight line. The seat system can further include a second actuator. The seat is able to rotate about a third axis which is non-intersecting with the horizontal plane. The first and second actuators are able to cause the seat to rotate about the second and third axes.
Embodiments may also include one or more of the following features. The second axis is substantially parallel to a direction in which the vehicle is moving when the vehicle is traveling in a straight line. The third axis is substantially perpendicular to a direction in which the vehicle is moving when the vehicle is traveling in a straight line. The second and third axes are substantially orthogonal to each other. The seat is able to translate substantially parallel to a second axis which is non-intersecting with a horizontal plane. The second axis is substantially parallel to a direction in which the vehicle is moving when the vehicle is traveling in a straight line. The second axis is substantially perpendicular to a direction in which the vehicle is moving when the vehicle is traveling in a straight line. The seat system further includes a second actuator. The seat is able to translate substantially parallel to a third axis which is non-intersecting with the horizontal plane. The first and second actuators are able to cause the seat to translate substantially parallel to the second and third axes. The second axis is substantially parallel to a direction in which the vehicle is moving when the vehicle is traveling in a straight line. The third axis is substantially perpendicular to a direction in which the vehicle is moving when the vehicle is traveling in a straight line. The one or more sensors include a sensor for detecting a roll rate of the vehicle about the first axis which is substantially parallel to a direction in which the vehicle is moving when the vehicle is traveling in a straight line. The one or more sensors includes a sensor for detecting a roll rate of the seat about a second axis which is substantially parallel to a direction in which the vehicle is moving when the vehicle is traveling in a straight line. The one or more sensors includes a sensor for detecting a lateral acceleration in a direction that is substantially perpendicular to a direction in which the vehicle is moving when the vehicle is traveling in a straight line and non-intersecting with the horizontal plane. The lateral acceleration sensor detects the lateral acceleration of the seat. The lateral acceleration sensor detects the lateral acceleration of the vehicle.
In another aspect, a method of controlling motion of a seat relative to a vehicle to which the seat is connected, includes the steps of receiving input at a processor from one or more sensors which can each measure an aspect of motion, and utilizing the processor to determine from the input a desired motion of the seat about a first axis which is substantially parallel to a direction in which the vehicle is moving when the vehicle is traveling in a straight line. As such, if a person were sitting in the seat, a combined motion of the vehicle relative to earth and the seat relative to the vehicle will result in that person being rotated about a position associated with their head or higher to substantially reduce side-to-side movement of the person's head. A signal is issued from the processor to cause an actuator to rotate the seat about the first axis to achieve the desired motion of the seat about the first axis.
Embodiments may include any of the above features and/or the following. The seat includes a seat bottom and a seat back which is connected to the seat bottom. The one or more sensors includes a sensor for detecting a roll rate of the vehicle about a second axis which is substantially parallel with the first axis. The one or more sensors includes a sensor for detecting a roll rate of the seat about the first axis. The one or more sensors includes a sensor for detecting a lateral acceleration in a direction that is substantially perpendicular to the first axis and non-intersecting with a horizontal plane. The lateral acceleration sensor detects the lateral acceleration of the seat. The lateral acceleration sensor detects the lateral acceleration of the vehicle. The processor receives an input that is indicative of a position of the actuator which is correlated to a position of the seat about the first axis.
In another aspect, a seat system for a vehicle includes a seat having a seat bottom on which a person can sit. An intermediate support structure is secured to the seat and the vehicle which allows the seat to rotate relative to the vehicle. An actuator can interact with the seat to cause the seat to rotate relative to the vehicle. One or more sensors can each measure an aspect of motion. A processor can (i) receive input from each of the one or more sensors, (ii) determine from this input a measure of rotation of the vehicle away from a nominal, level horizontal orientation, and (iii) utilize the input to determine a desired rotation of the seat. An angle that the seat has been rotated away from a nominal, level orientation is more than insubstantially larger than an angle that the vehicle has rotated away from a nominal, level horizontal orientation.
In a still further aspect, a method of controlling motion of a person relative to a vehicle in which the person is located includes providing a seat with a seat bottom on which the person can sit. Motion of the vehicle relative to earth is a rotation of the vehicle about an axis. A first imaginary reference vertical centerline passes through a body of the person who is sitting in the seat when both the seat and the vehicle are in a nominal, level horizontal orientation. The seat is secured to the vehicle. An aspect of motion is measured with one or more sensors. A processor is operated to (i) receive input from each of the one or more sensors, and (ii) utilize the input to determine a desired movement of a first portion of the vehicle relative to a second portion of the vehicle such that a combined motion of the second portion of the vehicle relative to the first portion of the vehicle and the first portion of the vehicle relative to earth results in motion of the person about a virtual pivot point located substantially along the reference vertical centerline.
Embodiments may include any of the above features and/or the following. An intermediate support structure is secured to the seat and the second portion of the vehicle which allows the seat to move relative to the second portion of the vehicle. A first actuator is connected between the seat and the second portion of the vehicle which can be operated to cause the seat to move relative to the second portion of the vehicle. The second portion of the vehicle includes a cab of the vehicle. The seat is able to be moved relative to the cab. The cab is able to be moved relative to the first portion of the vehicle.
The description below relates to a seat system for a vehicle. When a vehicle is rocked from side-to-side and/or fore/aft due to a disturbance in the road surface, the driver of the vehicle also experiences this motion. With the seat system discussed below, when the vehicle is rocked in one direction, the seat is rotated or translated relative to the vehicle in the opposite direction. As a result, acceleration of the driver's head in a horizontal direction is substantially reduced which results in a more pleasing driving experience for the driver.
Turning to
An intermediate support structure 18 is secured to the seat 16 and to a floor 20 of the vehicle 10 (structure 18 may be considered part of the seat 16). The intermediate support structure 18 allows the seat 16 to move/rotate relative to the vehicle about an axis 22 which is substantially parallel to a direction in which the vehicle 10 is moving when the vehicle is traveling in a straight line (if the seat 16 can be rotated so that it is not facing forward, the axis 22 may be skewed relative to this direction). In this example the axis 22 is closer to the floor 20 than to the seat bottom 14, and is preferably non-intersecting with a horizontal plane. The axis 22 can be located lower or higher than shown, but the seat 16 is preferably connected to the vehicle 10 at or near the floor 20. The axis 22 is fixed relative to the vehicle 10. Factors such as the distance it is desired to move the person's head about the axis 22, and sway space requirements (interference between seat parts and other portions of a vehicle cab 11 as the seat rotates) can be considered in choosing the height of axis 22 above the floor 20. The vehicle 10 can roll about an axis 24 which is substantially parallel with the axis 22.
In an alternative example, an asymmetrical seat system may be used. This can occur if, for example, a relatively large user interface for controlling the vehicle is mounted on one of two arm rests of the seat system (e.g. as on some farm tractors). In order to balance the seat over the axis 22, the seat 16 (including the seat bottom 14) will be offset relative to the support structure 18. For example, as viewed in
A distance L1 represents the length between the axis 22 and the axis 24. A distance L2 represents the length between the axis 22 and a center of a head 26 of the driver 12. The distance L2 is preferably assumed to be associated with a human being of above average height who is sitting in the seat 16 as opposed to setting L2 to be associated with a human being of average or below average height who is sitting in the seat 16. Preferably, the top end of L2 will reside at or above a position associated with a person's head who is sitting in the seat. It is preferred that L2 will be in the range of about 3-5 feet.
Referring to
The angle θ2 is calculated as follows by the processor: θ2=θ1×(1+L1/L2). This equation shows why locating the axis 22 close to the floor 20 is preferable. If L1 increases relative to L2 (the axis 22 is moved up away from the floor 20), θ2 increases. This means the seat 16 would have to be rotated through a larger angle to compensate for a fixed amount of vehicle roll as the axis 22 is moved up. This equation also shows that in this example θ2 will always be more than insubstantially larger than θ1. As a result, the person 12 is rotated about a position associated with their head 26 to substantially reduce or minimize side-to-side and/or front/back (discussed below) movement (i.e. acceleration in a horizontal direction) of the person's head. Preferably the head 26 remains substantially on the original vertical centerline 17. It should be noted that if the vehicle rotates through too large an angle (e.g. about axis 24), the seat may be rotated to its travel limit and not be able to rotate further to address the full angle of rotation of the vehicle. This would result in the head 26 of the person 12 not remaining on the vertical centerline 17. In an alternative example, the axis 22 can be located below the floor 20. A hole can be created in the floor, and the support structure 18 can be made longer in a vertical direction. This causes L1 to decrease and to L2 to increase, resulting in a relatively smaller θ2 (see the equation above)
The person 12 has not just been rotated so that they remain in a vertical position: they have been rotated beyond a vertical position. In other words, a combined motion of the seat 16 relative to the vehicle 10 and the vehicle 10 rotating (e.g. about the axis 24) results in motion of the person 12 about a virtual pivot point 33 located substantially along the reference vertical centerline 17. The virtual pivot point 33 is the intersection of the reference vertical centerline 17 with the seat centerline 31 as the seat 16 is displaced in space relative to earth. The virtual pivot point 33 is located at least above the location of the axis 24 (the vehicle rotation center). Preferably, the virtual pivot point 33 is located above the floor 20 of the vehicle 10. Even more preferably, the virtual pivot point 33 is located above the axis 22 (or the level where relative translation of the seat 16 with respect to the vehicle 10 occurs). Still further preferably, the virtual pivot point 33 is located above a position of a torso of the person 12 (assuming this person is of nominal height) when seated in the seat. Yet further preferably, the virtual pivot point 33 is located at or above a position of a center of the head of the person 12 (assuming this person is of nominal height) when seated in the seat. Preferably the virtual pivot point is about 1-4 feet above a surface of the seat bottom 14 on which the person can sit. More preferably the virtual pivot point is about 2-3 feet above a surface of the seat bottom 14 on which the person can sit. In
With reference to
The seat 16 described above has only a single degree of freedom about the axis 22 (a roll axis) relative to the vehicle 10. This single degree of freedom could instead be about a pitch axis. In this case, the axis 22 is oriented side-to-side as viewed in
Turning to
The processor 42 then issues a command to the actuator 36 via a bus 50 which cause the actuator to move to the desired actuator position. By successively repeating these steps, the processor 42 utilizes input from the sensor 44 to determine a desired motion of the seat 16 about the axis 22, and then operates the actuator 36 to cause the desired motion of the seat 16 about that axis. This results in a substantial reduction (or minimizing) of the acceleration of a person's head sitting in the seat 16 in a substantially horizontal direction. Preferably the processor 42 controls motion of the seat 16 in order to reduce displacement of the virtual pivot point 33 along the reference vertical centerline 17 as the vehicle 10 is rotated (e.g. about the axis 24 in
If it is desired to calculate L1 continuously in real time as the vehicle is moving, a lateral accelerometer (not shown) can be provided on, for example, the vehicle 10 or the seat 16. It is preferable that this accelerometer is located at substantially the same height (or location) as the axis 22. The processor 42 receives inputs from the lateral accelerometer and the roll rate sensor 44, and then calculates L1 using the equation L1=lateral velocity/roll rate where the lateral velocity is calculated by integrating the lateral acceleration signal. It should be noted that preferably gravity correction is done on the output of any lateral accelerometers described in this application. This means that the component of gravity coupled into the lateral accelerometer as the vehicle 10 and/or seat 16 rotates is taken into consideration.
In an alternative way of controlling the position of the seat 16 about the axis 22 in
With respect to
The seat system can include a mechanism (not shown in the Figures) to lock the seat 16 in its home position (shown in
In another example, the sensor package 56 is eliminated and a lateral accelerometer (not shown) is placed in a headrest (not shown) of the seat 16. The head rest, as is usual, can be adjusted to the height of the driver's head. The output of the lateral accelerometer is transmitted to the processor 42. The processor 42 uses the output from the lateral accelerometer to operate the actuator 36 in a way that substantially reduces, minimizes or eliminates acceleration of the drivers head in a horizontal direction (in this case, laterally). Gravity correction will need to be done on the output of the lateral accelerometer, and centrifugal forces from vehicle cornering need to be addressed by, for example, providing another accelerometer somewhere on the vehicle that can measure these centrifugal forces.
Referring to
The processor 42 calculates the integral of the roll rate data from the sensor 44 to determine an instantaneous roll angle θ1 (
Next, the processor 42 uses a lookup table to determine the desired actuator positions in order to achieve the calculated θ2 and θ5 angles. Actuators 36 and 64 will change only the angle θ5 when they are moved in unison. Actuators 36 and 64 will change only the angle θ2 when they are moved in opposition at the same velocities. Actuators 36 and 64 will change both the angle θ2 and the angle θ5 when they are moved at different velocities in the same or opposite directions. Note that the processor 42 receives position data from the actuators 36 and 64 by respective buses. The position data is indicative of a position of the actuators which is correlated to a position of the seat about the axes 22 and 62. As such, the processor is informed of the current position (e.g. extension) of the actuators.
The processor 42 then issues a command signal to each of the actuator 36 and 64 via respective buses which cause the actuators to move to the desired actuator positions. Note that the roll and pitch control signals for each actuator are combined by the processor 42 and then sent to the respective actuator 36 and 64. By successively repeating these steps, the processor 42 utilizes input from the sensors 44 and 66 to determine a desired motion of the seat 16 about the axes 22 and 62, and then operates the actuators 36 and 64 to cause the desired motion of the seat 16 about the axes. This example is advantageous in that it (a) is substantially insensitive to lateral accelerations caused by turning (when the vehicle makes a left or right turn) and gravity, as well as fore/aft accelerations caused by accelerating and braking the vehicle 10, and (b) requires minimal motion sensors. Note that the axes 22 and 62 are substantially orthogonal to each other. These axes can be oriented to be other than orthogonal to each other (i.e. other than 90 degrees offset from each other).
Turning to
The processor then plugs θ1 into the equation ΔXhead=(L1+L2)×θ1, where ΔXhead is the distance a person's head sitting in the seat 16 needs to be moved side-to-side to counteract rolling of the vehicle about the axis 24. For example, when the vehicle has rotated counter-clockwise (e.g. about the axis 24 in
The processor then plugs θ4 into the equation ΔYhead=(L4+L2)×θ4, where ΔYhead is the distance a person's head sitting in the seat 16 needs to be moved forwards or backwards to counteract pitching of the vehicle about the pitch axis. Next, the processor 42 uses a lookup table to determine the desired position of the actuator 76 in order to achieve the calculated ΔYhead. The processor 42 then issues a command to the actuator 76 which cause the actuator 76 to move to the desired actuator position. By successively repeating these steps, the processor 42 utilizes input from the sensor 66 to determine a desired motion of the seat 16 substantially parallel to the axis 22, and then operates the actuator 76 to cause the desired motion of the seat 16 substantially parallel to that axis. This example is advantageous in that it (a) is substantially insensitive to accelerations and decelerations caused by pressing the gas pedal or brake pedal of the vehicle 10, and gravity, and (b) requires minimal motion sensors. This arrangement assumes that there is a stationary pitch center height (i.e. L4 does not vary). If it is desired to use a time varying L4, a fore-aft accelerometer can be used as described above.
In
The roll rate sensor 44 provides a vehicle roll rate about the axis 24 to the processor 42. The pitch rate sensor 66 provides a vehicle pitch rate about the pitch axis (
A number of implementations have been described. Nevertheless, it will be understood that additional modifications may be made without departing from the spirit and scope of the inventive concepts described herein, and, accordingly, other embodiments are within the scope of the following claims. For example, another embodiment can include a seat that is both translated and rotated. This can be accomplished by modifying the seat shown in
In another version of a seat that is both translated and rotated, the seat system in
In all of the examples described above, the vehicle roll axis 24 was always shown located below the axis 22 about which the seat 16 is rotated (or below the level on which the seat is translated). The arrangements described above can also be used where a vehicle roll axis is located above a seat rotation axis or translation level. This can occur in a tram where a vehicle is suspended from a cable located above the vehicle.
In another example, the axis 22 (see
In a further example, the cab 11 is moved relative to another portion of the vehicle (e.g. the frame or fenders) in order to keep the virtual pivot point 33 located substantially along the reference vertical centerline 17. Such movement of the cab 11 can be in place of moving the seat 16 (in this case the seat 16 is secured in place relative to the cab 11), or in addition to moving the seat 11 (in this case the seat 16 is moved relative to the cab 11 and the cab 11 is moved relative to another portion of the vehicle 10). In the former case, the cab is moved by one or more of ΔXhead, ΔYhead, θ2 and θ4 as described above relative to another portion of the vehicle. In the latter case, the combined motion of the seat 16 relative to the cab 11, and the cab 11 relative to another portion of the vehicle is set to be one or more of ΔXhead, ΔYhead, θ2 and θ4 as described above. In this latter case the seat and cab move in the same direction which provides more travel room for the seat relative to the cab. U.S. Pat. No. 5,044,455, incorporated herein by reference, discloses actively moving a cab of a truck to address pitching of the truck as the truck travels over a road. The cab 11 can be moved as described in the '455 patent to address pitch and/or roll motions of the vehicle 10 under the control scheme described above.
The examples described above may include a processor with computer components and computer-implemented steps that will be apparent to those skilled in the art. For example, it should be understood by one of skill in the art that computer-implemented steps of a processor may be stored as computer-executable instructions on a computer-readable medium such as, for example, floppy disks, hard disks, optical disks, Flash ROMS, nonvolatile ROM, and RAM. Furthermore, it should be understood by one of skill in the art that the computer-executable instructions may be executed on a variety of processors such as, for example, microprocessors, digital signal processors, gate arrays, controllers, discrete logic, ASICs or other programmable logic device, or may be performed by analog circuitry, or by a combination of analog and digital circuitry.
