Patent Description:
Mobile imaging systems, such as mobile x-ray devices, are often mounted on motorized mobile drive systems such as carts that are drivable to a patient's location. The cart typically has four wheels, including a pair of wheels that are driven by a motor to move the system. The imaging assembly (such as an x-ray source or tube) may be encased in a horizontal tube arm, which may be mounted on a column proximate the front of the cart.

Mobile imaging systems, such as a mobile x-ray unit, may include an expandable tube arm attached to a column. Additionally, at the end of the tube arm opposite to the column, an imaging assembly, such as an x-ray tube and collimator, may be attached. The tube arm may contain several nested segments, which may extend and contract in a telescoping fashion. The column may rotate with respect to the cart, causing the tube arm to rotate with respect to the cart while fixed in relation to the column; additionally, the tube arm may radially extend and collapse, and translate linearly upwards and downwards along the column. The column may also contain multiple, nested segments which may extend to a point of maximal extension, and may collapse to a lowest, end position. In order to secure the tube arm for moving the mobile imaging system form one location to another, such as from one patient to another on a hospital floor, after operation of the mobile x-ray system, the tube arm may be placed in a parked position, and the column may be placed in a first collapsed position. Additionally, the column may further transition from the first collapsed position to an end position. Parking the tube arm and collapsing the column to an end position may make the mobile x-ray system more compact, and hence may allow for ease of transport for an operator of the mobile x-ray system.

In order to manipulate the imaging assembly and the tube arm, there may be a hand-actuatable component such as a first handle attached to the imaging assembly. Using the first handle, the operator may rotate the imaging assembly with respect to the tube arm and orient the tube arm in order to image a patient. In order to transport the mobile imaging system, the cart may have a second hand-actuatable component such as a second drive handle at the rear of the cart for the operator to push on. Using the second handle, the operator can drive the cart to a location, position the cart proximate to a patient's bed, and position the imaging assembly to image an anatomy of interest.

<CIT> describes a mobile radiography system including sensors to detect a tilt angle and or pitch angle of the system to prevent deployment of the extendable boom and/or column and/or prevent activation of a motor drive if the tilt angle or pitch angle exceeds a pre-set boundary.

The present disclosure relates to a mobile imaging system that allows a column of the mobile imaging system to be collapsed concurrently while allowing an operator to drive the mobile imaging system. An example embodiment of a mobile imaging system is given in <FIG>, in particular showing a column containing two, nested segments. <FIG> shows a system architecture in a block diagram form for the mobile imaging system of <FIG>. <FIG> shows an example orientation of the tube arm with respect to a cart of the mobile imaging system of <FIG>. <FIG> show example positions of the mobile imaging system in the process of transitioning from a first, operating position, to a fifth, fully collapsed position. In particular, <FIG> illustrate the tube arm containing two, nested segments. <FIG> show a flowchart illustrating an example method for transitioning the mobile imaging system from a first position as illustrated in <FIG> to a fifth position as illustrated in <FIG>.

As part of operating the mobile imaging system, in order to scan an anatomy of a patient, the operator may align the tube arm and a collimator mounted at the end of the tube arm at a particular orientation in relation to the patient. As an example, as part of aligning the mobile imaging system in relation to the patient, the mobile imaging system may be positioned proximate to the patient's bed. Further, the column may be in a fully extended position, the tube arm may be radially fully extended, and the tube arm (in conjunction with the column) may be rotated axially. After the operator has finished the imaging process, it may be desired to shift the system to a different location. The mobile imaging system may be reoriented from the operating position to a fully collapsed position, which may be efficient for transportation of the cart. The fully collapsed position may include the tube arm being fully radially retracted, being fixed to a cart of the mobile imaging system via a latch in a parked position, and the column being collapsed to a lowest, end position.

As part of the transition of the mobile imaging system from an imaging orientation to a fully collapsed position for transport, the operator may have to wait for the tube arm to first return to a fully parked position before the column begins to fully collapse. After the tube arm is parked and the column is fully collapsed in an end position, the operator may begin to drive the cart. This process may be time consuming in an environment where the operator may have many patients to attend within strict time constraints (e.g. in an intensive care unit or emergency room environment).

In one example, parking of the tube arm is initiated by exerting force on a first handle coupled to the imaging assembly. An imaging assembly may be coupled to the column via a rotatable and extendable tube arm, with a column coupling the tube arm to a drive system. Tube arm parking may be carried out by rotation of the tube arm to an origin position, retraction of the tube arm towards the column to a fully retracted position, and driving the tube arm vertically downwards along the column. Further, the retraction of the tube arm may be based on a first input from a first position sensor coupled to the column indicating a radial position of the tube arm, the driving of the tube arm vertically may be based on a second input from a second position sensor coupled to the tube arm indicating a vertical position of the tube arm relative to the column, and the rotation of the tube arm may be based on a third input from a third position sensor coupled to the column indicating an angular displacement of the column and the tube arm relative to the origin position. Each of the column and the tube arm may be moved linearly downwards even after the operator releases the first handle. While the tube arm is transitioned to a parked position and the column is transitioned to a first collapsed position, the operator may initiate movement of the cart by application of force to a second handle. After the tube arm and column are in a parked position, the operator may then initiate collapsing of the column to an end position via either a drive handle switch or by continuing to exert force on the second handle while driving the cart. As an example, the motion of the column from a parked position to a fully collapsed position may be carried out concomitantly while driving the cart forward. While the column may collapse at a constant speed, the speed of movement of the cart may be adjusted based on force feedback from the second handle.

In this way, by not waiting for the column to fully collapse before starting to drive the cart, the mobile imaging system may be transported faster to a desired location, thereby saving valuable time in a hospital floor. Tube arm parking actuation in response to an initial operator input to a first handle even after release allows the system to more efficiently transition to a position where the tube arm is secured for travel. In addition, the operator may initiate movement during tube arm parking, allowing a quicker transition from imaging to transport. Collapsing the column while concurrently driving the cart may provide a timesaving mechanism while still minimizing any visual impediment caused by the column. Overall, by expediting parking of the tube arm and collapsing of the column to the end position without waiting to drive the cart, workflow of the user may be made more efficient.

<FIG> illustrates an example <NUM> of a mobile imaging system <NUM> that may be used in the medical field or in other fields. The mobile imaging system <NUM> has a drive assembly <NUM> and an operator console <NUM> that may be supported by the drive assembly <NUM>. The drive assembly <NUM> comprises a frame <NUM> (also referred to herein as a cart) and two rear drive wheels <NUM> (one wheel is shown) coupled to the frame at a rear end <NUM> of the mobile imaging system <NUM> and two front wheels <NUM> (one wheel is shown) coupled to the frame at a front end <NUM> of the mobile imaging system <NUM>.

A column <NUM> is attached to, and extends upwardly from, the frame of drive assembly <NUM> and rotates or swivels with respect to the drive assembly <NUM>. Column <NUM> contains an outer segment <NUM>, and an inner segment <NUM>, which is nested within the outer segment <NUM>. The inner segment <NUM> is fixed to the cart <NUM>, while the outer segment <NUM> may telescope outwards from the inner segment <NUM> in response to operator manipulation. The outer segment may have a range of motions defined by a maximum focal point (where the column <NUM> is fully extended and the segments <NUM> and <NUM> have a minimal overlap) and a minimum focal point (where column is fully collapsed in an end position, with the outer segment fully encapsulating the inner segment). A tube arm <NUM> is fixed to the column <NUM>, extending perpendicular to the column. The tube arm <NUM> may be vertically adjustable relative to the column <NUM>, and may be otherwise fixed in its position relative to the column. In other words, the tube arm <NUM> may not rotate independently of the column <NUM>, but may co-rotate with the column as the column rotates with respect to the cart <NUM>. The tube arm may translate vertically along and independently along the axis <NUM> defined by the length of the column <NUM>, e.g., in response to user manipulation. The tube arm <NUM> may also telescope (such as project in and out horizontally) with respect to the column <NUM>, allowing components mounted at an outer end of the tube arm <NUM> to be moved closer to or further away from the column <NUM>.

An imaging assembly, herein in the form of a radiation source <NUM> including an x-ray source assembly <NUM>, is attached to the outer end of the tube arm <NUM> and has an x-ray tube housing <NUM> containing an x-ray source (not shown). A collimator <NUM> is attached to the tube housing <NUM> and is rotatable with respect to the tube housing <NUM>. An x-ray detector <NUM> detects x-ray data and may communicate with an imaging controller <NUM> wirelessly or over a cable <NUM>. Attached to the imaging assembly is a first hand-actuatable handle <NUM> (herein referred to as a first handle), which an operator may use to orient the tube arm and imaging assembly relative to the cart.

The tube arm <NUM> may include a first force sensor <NUM>. As an example, the first force sensor <NUM> may be placed on the top side of tube arm <NUM>, at the base of the tube arm <NUM> where the tube arm meets the column <NUM>. First force sensor <NUM> may measure forces along three independent, mutually perpendicular axes, such as a radial force applied to the first handle <NUM>, which may act to either expand or retract the tube arm <NUM>, a vertical force applied to the tube arm <NUM>, which may act to translate linearly upward or downward the tube arm <NUM> in relation to the column <NUM>, and a tangential force applied to the first handle <NUM>, which may act to co-rotate the column <NUM> and tube arm <NUM>. Additionally, first force sensor <NUM> may be coupled to a wire rope contained within column <NUM>. The wire rope may exit the outer segment <NUM> of the column and attach to the tube arm proximate to the first force sensor <NUM>, and the first force sensor <NUM> may be further configured to measure the force on the tube arm <NUM> due to the wire rope (as described in relation to <FIG>). Signals generated by first force sensor <NUM> in response to the forces applied to the first handle <NUM> may be sent to a controller <NUM>, which may then actuate motion of the tube arm <NUM> and/or the column <NUM>, as described in more detail in <FIG>.

Sensors may be included in the imaging assembly to measure either position and/or acceleration of various components. As an example, a first position sensor <NUM> coupled to the tube arm <NUM> may estimate the position of the tube arm <NUM> relative to the column <NUM> and the cart <NUM>, which may be used to estimate the extent of radial extension or retraction of the tube arm <NUM>. During actuation of the tube arm <NUM>, the first position sensor <NUM> may send a signal to controller <NUM>, which may then actuate further radial motion of the tube arm <NUM>, as described in more detail in relation to <FIG>. In another example, a second position sensor <NUM> may be coupled to the tube arm <NUM> to estimate the vertical position of the tube arm <NUM> (along the axis <NUM>) relative to the column <NUM>. The second position sensor <NUM> may send a signal to controller <NUM>, which may then actuate vertical translation of the tube arm <NUM> with respect to the column <NUM>, as described in more detail in relation to <FIG>. Sensors <NUM> and/or <NUM> may be optical sensors, magnetic sensors, pressure/force sensors, inertial measurement units (IMUs), or any variation of these sensors. It may be noted that the sensors of the various embodiments may be any suitable type or types of sensors. For example, one or more of the sensors may operate based on sensing a change in distance using optical, magnetic, electrical, or other mechanisms. In an additional example, a third position sensor <NUM> may be coupled to the column <NUM>, to estimate the angular displacement of the column <NUM> relative to the cart. The third position sensor <NUM> may send a signal to controller <NUM>, which may then adjust rotational motion of the column <NUM>, as described in further detail in relation to <FIG>. The sensor <NUM> may be an optical sensor, magnetic sensor, Hall effect sensor, or other suitable sensor adapted to detect the degree of rotation of column <NUM>. The placement of sensors <NUM>, <NUM>, and <NUM> as shown in <FIG> is exemplary, and other configurations are possible.

A second hand-actuatable interface is provided on system <NUM>, in the form of a second drive handle <NUM> (herein referred to as the second handle <NUM>) provided on the rear end <NUM> of the system <NUM>, such as coupled to the frame of drive assembly <NUM>. Controller <NUM> senses or receives signals based on the manipulation (e.g., user manipulation) of the second drive handle <NUM>, and the mobile imaging system <NUM> may be driven to different locations to image patients. As an example, the second handle <NUM> may detect a force applied to the handle via a second force sensor <NUM> contained within the handle, which may then send a signal to controller <NUM> to actuate the drive assembly <NUM>. The drive assembly <NUM> may include a drive motor <NUM>, and is capable of driving the rear drive wheels <NUM>.

A patient or subject <NUM> is typically positioned on a bed or table <NUM>. Once the mobile imaging system <NUM> is stationed near the table <NUM>, the column <NUM> is swiveled or rotated (e.g., via user manipulation) to position the x-ray source assembly <NUM> directly over the anatomy of the subject <NUM> to be scanned. The detector <NUM> is positioned on the opposite side of the subject <NUM>.

A user interface <NUM> may be provided proximate the rear end <NUM> of the system <NUM>. Optionally, the user interface <NUM> may be integrated with the second handle <NUM> or it may be configured as a remote control that may be held in the operator's hand away from the system <NUM>. The user interface <NUM> may communicate with the controller <NUM> wirelessly or over a wired connection. The user interface <NUM> may be one of, or a combination of, a button, joystick, toggle switch, power assist handle, provided as a key on a keyboard or a selection on a touchscreen, and the like. In some examples, the signals sent by the second handle <NUM> may be different than the signals sent by the user interface <NUM>. For example, the user interface <NUM> may send signals to switch drive modes, power on or off the system <NUM>, etc..

The controller <NUM> receives information from a plurality of sensors that indicates the position of the column <NUM>, tube arm <NUM>, collimator <NUM>, and/or x-ray source assembly <NUM>. Further, controller <NUM> may receive force information that indicates the extent of force applied to the first handle <NUM> and the second handle <NUM>. In response to positional and force information, controller <NUM> may actuate a plurality of motors (such as a first servomotor <NUM>, a second servomotor <NUM>, a third servomotor <NUM>, the drive motor <NUM>, and a column motor <NUM>, all of which will be discussed further in relation to <FIG>), which may control the motion of the tube arm <NUM>, the column <NUM>, and the drive wheels <NUM> of system <NUM>. Additionally, controller <NUM> may receive signals from user interface <NUM>, as described above.

<FIG> illustrates an example <NUM> of control system and components for actuation of each of the column, the tube arm, and the drive assembly of the mobile imaging system <NUM> of <FIG>. The mobile imaging system <NUM> may be controlled via a controller <NUM>, which may receive signals from a plurality of sensors further described herein.

In order to actuate motion of the tube arm <NUM>, the controller <NUM> may receive signals from a first handle <NUM> via a first force sensor <NUM>. The first handle <NUM> may be coupled to the first force sensor <NUM>, as described in relation to <FIG>. The output of the first force sensor <NUM> may estimate a force applied on the first handle. Upon receiving force signals from first force sensor <NUM>, controller <NUM> may initiate motion of the tube arm via tube arm actuators <NUM>. Tube arm actuation may include two independent degrees of motion of the tube arm <NUM>: radial expansion and retraction of the tube arm <NUM> and vertical translation of the tube along the column. For each of the independent degrees of motion of the tube arm <NUM>, there is a corresponding servomotor, the first servomotor <NUM> and the second servomotor <NUM>, to provide force feedback along the respective degrees of motion (as described further in relation to <FIG>). Additionally, there may be the third servomotor <NUM> to provide force feedback for rotation of the column with respect to the cart, in response to a signal received from the first handle <NUM>.

A servomotor may contain a motor coupled to a position sensor, which may then send a signal to the motor for actuation in response to the position information. As an example, a servomotor may contain an internal position encoder, such as a rotary encoder, which may estimate the angular position of a shaft contained within the motor. The positional information of the shaft contained within the motor may then be sent to a controller to actuate the motor. Additionally or alternatively, a servomotor may contain an external position sensor, which may record the position of a component external to and driven by the motor. The signal obtained from the external position sensor may then be sent to a controller to actuate the motor. Further, a servomotor can be configured to actuate in response to signals from a force sensor, in conjunction with positional signals received from a position sensor.

As an example, the first servomotor <NUM> may provide power for radial expansion and retraction of the tube arm. This may involve receiving the force information from first force sensor <NUM> of force applied radially along the tube arm, in addition to positional information from first position sensor <NUM> of an outer segment of the tube arm <NUM> (as described in relation to <FIG>). The force and positional information obtained from sensors <NUM> and <NUM> respectively may then be sent to controller <NUM> to actuate the second servomotor <NUM> to apply power to radially expand or contract tube arm <NUM> at a set velocity. The set velocity of the tube arm <NUM> may be determined via a force feedback loop based on the radial force estimated from the first force sensor <NUM>.

As an example of the above force feedback loop, a first proportional integral (PI) controller may be used to adjust power delivered to the first servomotor <NUM>. A setpoint of the first PI controller may be adjusted based on each of the output of first force sensor <NUM> and the output of the first position sensor <NUM>. The first PI controller may receive a difference between a setpoint power and actual power delivered to the first servomotor <NUM>. At the first PI controller, the error may be processed and/or modified (scaled) by a proportional gain. The integral of the error may be similarly processed and/or modified (scaled) by an integral gain. One of these terms or their sum is then output as a signal. The output signal of the first PI controller may produce the final control signal to be sent to the motor of the first servomotor <NUM>.

As another example, the second servomotor <NUM> may provide power for vertical translation of the tube arm <NUM> along the column <NUM>. The second servomotor <NUM> may first receive force information from first force sensor <NUM> of force applied vertically along the tube arm, in conjunction with positional information from sensor <NUM> of the tube arm <NUM> along the height of the column. The force and positional information obtained from sensors <NUM> and <NUM> respectively may then be sent to controller <NUM> to actuate the second servomotor <NUM> to apply power to translate tube arm <NUM> upwards or downwards at a set velocity. The set velocity of the tube arm <NUM> may be determined via a force feedback loop based on the vertical force estimated from first force sensor <NUM>.

As an example of the above force feedback loop, a second proportional integral (PI) controller may be used to adjust a power delivered to the second servomotor <NUM>. A setpoint of the second PI controller may be adjusted based on each of the output of the first force sensor <NUM> and the output of the second position sensor <NUM>. The second PI controller may receive a difference between in a setpoint power and actual power delivered to the second servomotor <NUM>. At the second PI controller, the error may be processed and/or modified (scaled) by a proportional gain. The integral of the error may be similarly processed and/or modified (scaled) by an integral gain. One of these terms or their sum is then output to a signal. The output signal of the second PI controller may produce the final control signal to be sent to the motor of the second servomotor <NUM>.

Similarly, the third servomotor <NUM> may provide power for axial rotation of the column <NUM>. This may involve receiving the force information from first force sensor <NUM> of a tangential force on the tube arm, in addition to angular positional information from third position sensor <NUM>. The force and positional information obtained from sensors <NUM> and <NUM> respectively may then be sent to controller <NUM> to actuate the third servomotor <NUM> to apply power to rotate column <NUM> at a set velocity. The set velocity may be determined via a force feedback loop based on the tangential force estimated from first force sensor <NUM>.

As an example of the above feedback loop, a third proportional integral (PI) controller may be used to adjust a power delivered to the third servomotor <NUM>. A setpoint of the third PI controller may be adjusted based on each of the output of the first force sensor <NUM> and the output of the third position sensor <NUM>. The third PI controller may receive a difference between in a setpoint power and actual power delivered to the third servomotor <NUM>. At the third PI controller, the error may be processed and/or modified (scaled) by a proportional gain. The integral of the error may be similarly processed and/or modified (scaled) by an integral gain. One of these terms or their sum is then output to a signal. The output signal of the third PI controller may produce the final control signal to be sent to the motor of the third servomotor <NUM>.

Additionally, each of the servomotors <NUM>, <NUM> and <NUM> respectively may include internal velocity sensors. In alternate embodiments, the position sensors (such as first position sensor <NUM>, second position sensor <NUM>, and third position sensor <NUM>) may be replaced with accelerometers.

Controller <NUM> may also receive input signals from several other sources, including the user interface <NUM>, an emergency stop mechanism <NUM>, an emergency column drive stop mechanism <NUM>, and a column switch <NUM>. At any time during operation, controller <NUM> may be configured to receive and act upon an input from one or more emergency stop mechanisms <NUM>, which may include one or more of a button, sensor, bumper and the like, and which may act to deactivate the drive wheels <NUM>. Controller <NUM> may also be configured to receive and act upon inputs from a column drive stop mechanism <NUM>. As an example, the column stop mechanism <NUM> may deactivate further collapse of the column in response to e.g. insufficient power from a battery <NUM>. As a further example, controller <NUM> may discontinue actuation of the column motor <NUM> in response to the column switch <NUM>. As another example, if the column is in a fully collapsed, end state, the column switch <NUM> may indicate that the column is in a fully collapsed position, which may cause the controller <NUM> to deactivate further collapse of the column <NUM>.

Additionally, example control system <NUM> may include the drive assembly <NUM>, which houses drive motor <NUM>. The drive motor <NUM> may actuate the drive wheels <NUM> via controller <NUM> in response to a force signal detected by the second force sensor <NUM> contained within the second handle <NUM>. The drive wheels <NUM> may rotate at a speed may be determined by the force detected by the second force sensor <NUM> via a force feedback mechanism. Said another way, moving the drive system may include actuating a set of drive wheels <NUM> coupled to the drive system with a speed of the drive wheels <NUM> adjusted based on signals received from a second force sensor <NUM> coupled to the second handle <NUM>. The force feedback mechanism for drive motor <NUM> may be substantially similar to the force feedback mechanisms for servomotors <NUM>, <NUM>, and <NUM>, whereby the drive motor <NUM> may provide power to the drive wheels <NUM> in response to the force applied to the second handle <NUM>. The power applied to the drive wheels <NUM> by drive motor <NUM> may then cause the drive wheels <NUM> to rotate at a set speed, the set speed determined by the force applied to the second handle <NUM>.

The second handle <NUM> may also contain a drive switch <NUM>, which may actuate the column collapsing from a first, collapsed state to a fully collapsed state (as described in relation to <FIG>).

Further, example control system <NUM> may include column actuators <NUM>, which may contain the aforementioned third servomotor <NUM>, and the column motor <NUM>. Column motor <NUM> may be a servomotor, which may contain a motor and an internal position sensor (such as an encoder or potentiometer), the latter of which may record positional information about the shaft within the column motor <NUM>. The degree of extension of the column <NUM> may be inferred from positional information of the internal position sensor of column motor <NUM>, with end of travel positions defined by predefined values within the extension range. Additionally, column motor may receive force information from the first force sensor <NUM>, and may provide power for the collapse of the column <NUM> based off of force information from the first force sensor <NUM>, and positional information of the degree of extension inferred from the internal position sensor of column motor <NUM>. Additionally or alternatively, the column motor <NUM> may provide power for collapsing the column based off of input from the drive switch <NUM>. As a first example, in response to force applied to the second handle <NUM>, column motor <NUM> may drive down the column <NUM> at a set velocity, the velocity determined by the force applied to the second handle <NUM> via a force feedback mechanism. As a second example, the column motor may drive down the column <NUM> at a fixed velocity in response to input from the drive switch <NUM>.

The actuators of system <NUM>, such as the column actuators <NUM>, the drive assembly <NUM>, and the tube arm actuators <NUM>, in addition to the controller <NUM>, may be powered by battery <NUM>, which may be a rechargeable energy storage device.

<FIG> is a schematic diagram <NUM> illustrating the orientation of the drive assembly <NUM> and tube arm <NUM> with respect to each other. The column <NUM> (not shown in <FIG>) pivots with respect to the drive assembly <NUM> at a pivot point <NUM>. For example, referring to <FIG>, a center of the column <NUM> may define the pivot point <NUM>. The drive assembly <NUM> may have a coordinate system, containing of a longitudinal axis <NUM>, which extends parallel to the length of the drive assembly <NUM> and is centered symmetrically along the length of the drive assembly <NUM>, a latitudinal axis <NUM>, which extends perpendicular to the longitudinal axis <NUM> and intersect the longitudinal axis <NUM> at the pivot point <NUM>, and a vertical axis <NUM>, defined by the length of the column (not shown). The vertical axis <NUM> is perpendicular to both the longitudinal axis <NUM> and the latitudinal axis <NUM>, and intersects both at the pivot point <NUM>.

As shown in <FIG>, the column <NUM> is pivoted with respect to the longitudinal axis <NUM> such that a center line <NUM> of the tube arm <NUM> is at an angle of rotation Φ with respect to the longitudinal axis <NUM>. As used herein, the angle of rotation Φ is equal to zero when the center line <NUM> of the tube arm is coincident with the longitudinal axis <NUM>, and may describe the angle of rotation Φ of the column <NUM> with respect to the longitudinal axis <NUM>. As the tube arm <NUM> co-rotates as the column <NUM> rotates and may not rotate independently of the column <NUM>, the angle of rotation Φ may also refer to the angle of rotation of the tube arm <NUM> with respect to the longitudinal axis. The angle of rotation Φ may increase (with positive values) as the column is rotated clockwise and increase with negative values as the column is rotated counter clockwise. The angle of rotation Φ when the tube arm <NUM> is in the parked position is <NUM>, so that the tube arm <NUM> is parallel with the longitudinal axis <NUM>. Additionally, the tube arm <NUM> may expand and retract along the axis defined by the center line, as indicated by <NUM>.

<FIG> show various configurations of the mobile imaging system <NUM> in transition from a first position in an imaging orientation to a final position during transportation of the imaging system. Additionally illustrated in <FIG> are arrows indicating motion of various parts of mobile imaging system <NUM> during transitions between positions, and a coordinate system <NUM> indicating mutually perpendicular directions x,y and z.

<FIG> shows mobile imaging system <NUM> in a first position. A first position may be a position in which the mobile imaging system <NUM> may be in an imaging configuration for imaging a patient (not shown). As an example, the first position may include the column <NUM> being fully extended to a maximal length, the tube arm <NUM> being extended radially to a maximal length, and the angle of rotation Φ of the column <NUM> and tube arm <NUM> with respect to the longitudinal axis is <NUM> degrees. As examples, the extent of extension of the column <NUM>, extent of extension of the tube arm <NUM>, and the non-zero angle of rotation Φ of the column <NUM> and the tube arm <NUM> for the imaging configuration may take on a range of values.

The internal components of tube arm <NUM> and column <NUM> are shown in <FIG>. The tube arm <NUM> is shown to contain an inner segment <NUM>, which is nested within an outer segment <NUM>, and may extend and contract within a pre-defined range of motion along an axis of the tube arm (such as the axis defined by the center line <NUM> of the tube arm <NUM>, as shown in <FIG>). Also shown within the tube arm <NUM> are the tube arm actuators <NUM>, which may include servomotors <NUM> and <NUM> for two independent degrees of motion of the tube arm, as described in detail for <FIG>. However, the exact placement of tube arm actuators <NUM> and the servomotors contained therein is exemplary. Contained within the column <NUM> are a variety of components which may actuate the collapse of the column <NUM> to an end position. Housed within both the inner segment <NUM> of the column <NUM> and the outer segment <NUM> of the column <NUM> is a first gas spring <NUM>, which may provide a counterbalancing force to the tube arm and column, additional external loads of the cart <NUM>, and friction between the inner segment <NUM> and the outer segment <NUM>, aiding in positioning the column <NUM> at a particular height. The first gas spring <NUM> is extendable along the full length of the inside of the column <NUM>. Proximate to first gas spring <NUM> is ball screw <NUM>, which is housed within both the inner segment <NUM> and the outer segment <NUM>, and is fixed to the top of the inside of outer segment <NUM>. Ball screw <NUM> may be actuated by a ball nut <NUM>, which is housed within inner segment <NUM>, and may be driven by a column motor <NUM> via a belt drive <NUM>. The column motor is housed within inner segment <NUM>, while the belt drive is placed externally on the top of inner segment <NUM>. The ball nut <NUM> may rotate in response to actuation by column motor <NUM> via belt drive <NUM>, and may lower the outer segment <NUM> by the induced downward motion of ball screw <NUM> due to rotation of ball nut <NUM>.

Also internal to the column <NUM> is a tension gas spring <NUM> (herein referred to as the second gas spring), which is housed within the inner segment <NUM> and fixed internally to the top of inner segment <NUM>. Second gas spring <NUM> may expand and contract within the inner segment <NUM>, and may transmit an upward force to the tube arm <NUM> via a wire rope <NUM>. The wire rope <NUM> is attached to the top of the inside of the inner segment <NUM>, and is under tension and in contact with the second gas spring <NUM> via a pulley attached to the second gas spring. The wire rope <NUM> exits from the top of the inner segment <NUM> and wraps around another pulley within the interior of the outer segment <NUM>, exiting the outer segment and attaching outside of the tube arm <NUM>. The wire rope <NUM> is of a fixed length, and may be put under increasing tension due to increased expansion of the of second gas spring <NUM>. In the first position of <FIG>, the second gas spring <NUM> is compressed, and the wire rope <NUM> extends within the interior of the extended outer segment <NUM>.

<FIG> shows mobile imaging system <NUM> transitioning from a first position to a second position. The second position may contain the tube arm <NUM> rotated from an imaging orientation (an example angle of rotation Φ of the column <NUM> and the tube arm <NUM> is given as <NUM> degrees in <FIG>) to an origin position, where the angle of rotation Φ of the column <NUM> and the tube arm <NUM> is <NUM> degrees. The second position may also include the tube arm <NUM> to be in a fully retracted position. The tube arm rotation may be due to the force applied to the first handle <NUM> by an operator <NUM>. In response to force applied to the first handle <NUM> by an operator <NUM>, a third servomotor (such as third servomotor <NUM> of <FIG>) may act to drive tube arm rotation at a set velocity determined by the applied force via a force feedback mechanism. Additionally, <FIG> illustrates tube arm retraction from a fully extended position (as shown in <FIG>) to a fully retracted position. The tube arm retraction may be due to force applied to the first handle <NUM> by operator <NUM>, and in response to force applied to the first handle <NUM> by an operator <NUM>, a first servomotor (such as first servomotor <NUM> of <FIG>) may act to drive tube arm retraction at a set velocity determined by the applied force via a force feedback mechanism. The retraction motion of the tube arm <NUM> is indicated by arrow <NUM> parallel to the x axis of coordinate system <NUM>.

<FIG> shows mobile imaging system <NUM> transitioned from a second position to a third position. The third position may include the tube arm <NUM> fully retracted and in a parked position. The parked position may include the tube arm <NUM> being fully radially retracted, the tube arm being aligned parallel to the longitudinal axis <NUM> with angle of rotation Φ of the tube arm <NUM> being <NUM>, and the tube arm <NUM> being in a vertically lowered position relative to the column <NUM>, being fastened to the cart <NUM> via latches <NUM> and <NUM>. Additionally, as part of the parked position, column <NUM> may be in a first collapsed position. The tube arm may be translated vertically from a maximum focal point (as shown in <FIG>) to a parked position due to the force applied to the first handle <NUM> by the operator <NUM>; this motion is indicated by arrow <NUM> parallel to the z axis of coordinate system <NUM>. The vertical translation of the tube arm <NUM> may be based on force feedback in response to a force applied to the first handle <NUM> by operator <NUM> via a second servomotor (such as the second servomotor <NUM> of <FIG>). The velocity of the tube arm parking may be set, via force feedback, based on the force applied by the operator <NUM> to the handle <NUM>. Additionally, after an initial downward force applied to the first handle <NUM> by operator <NUM>, the operator <NUM> may let go of the first handle <NUM>, and the tube arm may continue to translate vertically along the axis <NUM> at a fixed velocity, determined by the velocity of the tube arm upon release of the handle, and the force applied to the handle upon release. As the tube arm <NUM> is lowered to the parked position, tube arm <NUM> may attach to cart <NUM> via latches <NUM> and <NUM>, which are attached to the tube arm <NUM> and the cart <NUM>, respectively. The latches <NUM> and <NUM> may indicate to the controller <NUM> that the tube arm is in a parked position upon fastening via latch sensor <NUM>. Concomitantly with the tube arm parking, the outer segment <NUM> of the column <NUM> may partially retract from a maximal focal point to a first collapsed position in response to the force applied to the first handle <NUM> by operator <NUM>. The force applied to first handle <NUM> is estimated by first force sensor <NUM>, which detects the direction and magnitude of the force, and actuates the column motor <NUM> to retract the column via controller <NUM>. The retraction motion of the outer segment <NUM> is indicated by arrow <NUM> parallel to the z axis of coordinate system <NUM>. The column motor <NUM> drives the ball nut <NUM> via belt drive <NUM>, which induces a downward motion of ball screw <NUM>, lowering the outer segment <NUM>. As an example, the column first collapsed position may be <NUM>% between the fully extended and fully collapsed positions.

<FIG> shows mobile imaging system <NUM> transitioned from a third position to a fourth position. The forth position may include the tube arm <NUM> in a parked position, and the column <NUM> in a position intermediate between a first collapsed position and an end position. The intermediate position of the column may take on a range of values. The outer segment <NUM> of the column <NUM> may continue to retract in response to a signal received from the operator applied to the drive handle <NUM>, as indicated by arrow <NUM>. Alternatively, the operator may actuate a drive switch <NUM> located on an instrument panel or proximal to the second drive handle to initiate collapsing of the column to the end position. The operator <NUM> pressing the second handle <NUM> may cause the column motor <NUM> to be actuated via controller <NUM>, which may drive down the outer segment <NUM> to the fully collapsed, end position. During the collapse of the column <NUM> to an end position, the second gas spring <NUM> may expand to provide additional tension on the wire rope <NUM>. The time for the column <NUM> to collapse from a parked state to an end state may be a fixed duration. As an example, the time for the outer segment <NUM> to go from a first collapsed position to an end position may take less than <NUM> seconds.

During the column collapsing to the end position, a force may be applied by an operator <NUM> to the second handle <NUM>. Force applied to the second handle <NUM> may be estimated by a second force sensor <NUM> contained within the handle. The force sensor <NUM> may then send a signal to controller <NUM>, which may then actuate the drive motor <NUM>, actuating drive wheels <NUM>. The drive wheels may be operated concurrently with collapsing of the column. The speed of the drive wheels <NUM> may be determined, via force feedback, based on the force applied to the second handle <NUM>. The motion of the cart <NUM> is indicated by arrow <NUM> parallel to the x axis of coordinate system <NUM>.

<FIG> shows mobile imaging system <NUM> in a fifth position. In the fifth position, the tube arm is parked and the column is in an end position, with the second gas spring <NUM> fully expanded to maintain tension within the wire rope <NUM>. The drive wheels <NUM> may continue to be driven at a speed determined via force feedback from the second handle <NUM>, as described above. The motion of the cart <NUM> is indicated by arrow <NUM> parallel to the x axis of coordinate system <NUM>.

In this way, the systems in <FIG> provide for a system for a mobile imaging system comprising a controller storing instructions in non-transitory memory executable by the controller for: during a first condition, collapsing a column coupling a tube arm and a drive system of the mobile imaging system at a first speed while driving the drive system forward at a second speed; and during a second condition, collapsing the column at the first speed while driving the drive system forward at a third speed, the third speed higher than the second speed.

<FIG> show a flowchart illustrating a method <NUM> for parking a tube arm (such as tube arm <NUM> of <FIG>) and collapsing a column (such as column <NUM> of <FIG>) to an end position in a mobile imaging device, such as system <NUM>. Instructions for carrying out method <NUM> and the rest of the methods included herein may be executed by a controller (e.g., controller <NUM> shown in <FIG>) based on instructions stored on a memory of the controller and in conjunction with signals received from sensors of the mobile imaging system, such as the sensors described above with reference to <FIG>. The controller may employ actuators of the mobile imaging system to move the mobile imaging system, according to the methods described below. In particular, the controller may employ a drive motor (such as drive motor <NUM> of <FIG>) to actuate the drive wheels (such as drive wheels <NUM> of <FIG>), two separate servomotors (such as a first servomotor <NUM> and a second servomotor <NUM> of <FIG>) to actuate tube arm motion along two independent degrees of motion, and a third servomotor (such as third servomotor <NUM> of <FIG>) and a column motor (such as column motor <NUM> of <FIG>) to actuate rotation and collapse of the column, respectively.

At <NUM>, method <NUM> determines if the conditions have been met for parking of the tube arm. The conditions for parking may include receiving signals of force being applied to a first handle (such as first handle <NUM> of <FIG>) by an operator. As described in relation to <FIG>, the first handle may translate user movement into movement of the arm and/or column of the mobile imaging system, and may be coupled to a variety of sensors, including a first force sensor (such as a first force sensor <NUM> or <FIG>), which may detect forces applied to the first handle and send signals to the controller to actuate of the tube arm and/or the column. The first force sensor may also detect forces on the tube arm due to a wire rope (such as wire rope <NUM> of <FIG>) internal to the column, and may sense additional force on the tube arm due to the wire rope. Additionally, the first handle may be coupled to position sensors (such as the first position sensor <NUM>, the second position sensor <NUM>, and the third position sensor <NUM> of <FIG>), which may send position signals corresponding to the position of the tube arm with respect to a vertical axis (such as axis <NUM> of <FIG>), the radial extension of the tube arm, and the angle of rotation Φ of the column and tube arm with respect to the cart. The conditions for parking the tube arm may also include indication of completion of a scan by a user via an input to the instrument panel. The conditions for parking may further include the drive wheels being deactivated or maintaining a deactivated state, an x-ray source (such as x-ray source <NUM> of <FIG>) being deactivated or maintaining a deactivated state, an imaging controller (such as imaging controller <NUM> of <FIG>) being deactivated or maintaining a deactivated state, and an imaging assembly (such as imaging assembly of <FIG>) being oriented in a start position, where the degree of rotation of the imaging assembly is zero with respect to the tube arm.

If the conditions of <NUM> are not met, method <NUM> may proceed to <NUM>, where the tube arm may be maintained in under normal operation. Normal operation of the tube arm may include motion of the tube arm and column based on force exerted on the tube arm such as rotation, extension, and/or retraction of the tube arm as driven by motors (such as the first, second and third servomotors, and the column motor) via force feedback. Method <NUM> may then proceed again to <NUM>. If the conditions for tube arm parking are met, method <NUM> may proceed to <NUM>.

At <NUM>, method <NUM> may proceed to drive the tube arm to a parked position based on force feedback from the first handle. The tube arm may be driven to a parked position in response to a force applied to the first handle. The driving motion may involve three separate driving mechanisms such as rotation of the column (causing corresponding rotation of the tube arm), retraction of the tube arm, and vertical downward translation of the tube arm. In other words, each of the rotation of the tube arm, the retraction of the tube arm, and the driving of the tube arm vertically may be adjusted based on a force feedback responsive to first signals received from the first force sensor coupled to the first handle of the tube arm. As an example, actuating the tube arm to the parked position may include rotating the tube arm to an origin position via rotation of the column (as discussed in relation to <FIG>), retracting tube arm horizontally to a fully retracted position by retracting an inner tube segment within an outer tube segment, and translating the tube arm vertically downward along the column. However, the order in which the operations take place is exemplary, and may be rearranged. For example, the tube arm may first be retracted, then the column may be rotated, and finally the tube arm may be placed in a parked position. As a further example, the rotation of the column and the retraction of the tube arm may be done in conjunction prior to being in an origin position, after which the tube arm may be driven to a parked position.

Driving the tube arm to a parked position may include, at <NUM>, rotation of the column based on force feedback in response to a force applied to the first handle. A tangential force applied to the first handle may cause the column and tube to co-rotate with respect to the cart. The angular displacement of the column may be estimated by the third position sensor, which may then send a signal to the controller to actuate a third servomotor to drive rotation of the column at a set velocity. The set velocity may be set in accordance with the tangential force applied the first handle and the angular displacement, via the force feedback mechanism described in relation to <FIG>. The force feedback mechanism may include determining the power applied to the third servomotor based on positional and tangential force information from the third position sensor and the first handle, respectively. The difference between the setpoint power and the actual power applied to the third servomotor may then be proportional to the tangential force applied to the first handle, as determined by a first PI controller of the first servomotor.

Driving the tube arm to a parked position may involve, at <NUM>, retracting the tube arm based on force feedback in response to a radial force applied to the first handle. A radial inward force may cause the tube arm to retract towards the column. The position of e.g. an inner segment of the telescoping tube arm (such as inner segment <NUM> of <FIG>) may be estimated by the first position sensor, which may then send a signal to the controller to actuate a first servomotor to drive the retraction of the tube arm at a fixed velocity in response to the radial force applied to the first handle and the position of the inner segment of the tube arm, via the force feedback described in relation to <FIG>. The force feedback mechanism may include determining the power applied to the first servomotor based on positional and radial force information from the first position sensor and the first handle, respectively. The difference between the setpoint power and the actual power applied to the first servomotor may then be proportional to the radial force applied to the first handle, as determined by a second PI controller of the second servomotor.

Further, driving the tube arm to a parked position may also involve, at <NUM>, driving the tube arm linearly downward based on force feedback in response to a vertical downward force applied to the first handle. A vertical downward force may cause the tube arm to translate vertically downwards along the vertical axis of the column. The position of the tube arm along the vertical axis in relation to the column may be estimated by the second position sensor, when may then send a signal to the controller to actuate a second servomotor to drive the tube arm linearly downward at a fixed velocity determined by the vertical force applied to the first handle, via the force feedback mechanism described in relation to <FIG>. The force feedback mechanism may include determining the power applied to the second servomotor based on positional and vertical force information from the second position sensor and the first handle, respectively. The difference between the setpoint power and the actual power applied to the second servomotor may then be proportional to the vertical force applied to the first handle, as determined by a second PI controller of the second servomotor. Further, the tube arm may be driven even after a force applied to the first handle is ceased, e.g. due to an operator (such as operator <NUM> of <FIG>) releasing the first handle. After release of the first handle, the driving may be determined by the position of the tube arm relative to the column, the vertical downward force applied to the handle upon release, and the vertical downward speed of the tube arm with respect to the column upon release.

Concurrently with driving the tube arm linearly downward to a parked position as indicated in <NUM>, the column may be driven down at a constant speed to a first collapsed position, which may not be the fully collapsed end position, as indicated in <NUM>, through actuation of a ball screw (such as ball screw <NUM> of <FIG>) by a column motor. In other words, while actuating the tube arm to the parked position, the column may be concurrently collapsed by collapsing an outer column segment encapsulating an inner column segment until a first collapsed position is reached. The column motor may be actuated in response to a linear downward force applied to the first handle, which may cause a signal from the first force sensor to be sent to the controller, which may then actuate the column motor to drive down an outer segment of the column (such as outer segment <NUM> of the column of <FIG>). The column motor may drive the ball screw via a belt drive (such as belt drive <NUM> of <FIG>), which may then cause a ball nut (such as ball nut <NUM> of <FIG>) to rotate, forcing the ball screw to rotate in conjunction with the rotational motion of the ball nut and translate linearly downwards. The ball screw, which may rotate relative to the column (e.g. may be fixed to the top of the interior of the outer segment of the column by a flange bearing) may then drive the outer segment of the column linearly downwards due to the linear downwards motion of the ball screw.

In conjunction with the column driving, at <NUM>, weight compensation may be provided internally to the column as it is driven downwards via a first gas spring (such as first gas spring <NUM> of <FIG>). The first gas spring may provide a counteracting force to the column to control the motion of the column as it is driven down by the column motor. The first gas spring may be fixed to the bottom of the inside of an inner segment of the column (such as inner segment <NUM> of <FIG>) and the top of the inside of the outer segment of the column, and may extend if the compression force applied is less than the extension force of the first gas spring, and may otherwise compress according to the difference of the compression and extension forces. The compression forces applied to the first gas spring may include the weight of the tube arm, the force of the frame and outer segment of the column in the absence of driving, additional force of the frame and outer segment of the column in the presence of driving, and additional frictional force within the first gas spring. As an example, the force that the first gas spring may apply to the frame and outer segment of the column may be approximately (e.g. with a margin of error of <NUM>%) 1300N fully compressed, and 800N fully expanded.

At <NUM>, method <NUM> may check if the tube arm is in a parked condition. The tube arm being in a parked condition may include the tube arm being fastened securely to the cart via latches (such as a latch <NUM> fixed to the tube arm and a latch <NUM> fixed to the frame, as shown in <FIG>), the tube arm being fully radially retracted, the column and tube arm having an angle of rotation Φ of <NUM> with respect to a longitudinal axis (such as longitudinal axis <NUM> of <FIG>) of the cart, and the column being in a first collapsed position. As an example, the latches may include sensors (such as latch sensor <NUM> of <FIG>), which may send a signal to the controller to indicate that the tube arm is in a parked position upon fastening of the latches. Additionally or alternatively, the parked position may be indicated by positional data for the tube arm and the column estimated by the first position sensor, the second position sensor and the third position sensor, which may be stored and recorded in the controller.

If the above conditions for tube arm parking are not met, it may be inferred that the tube arm parking is not finished. The method <NUM> may proceed to <NUM> to determine if signals are received from the second handle during tube arm parking. The mobile imaging system may include a second handle (e.g., drive handle <NUM>) that outputs signals to the controller indicative of a desired direction of movement of the mobile imaging system. In one example, the mobile imaging system may also include a switch (such as on an instrument panel or on a smart device communicatively connected to the imaging system) that may be actuated to indicate a desire to move the imaging system to an end position and to move the system from one location to another. In response to the above signals, the controller may activate drive wheels (such as drive wheels <NUM> of <FIG>), in order to move the mobile imaging system. Accordingly, if signals are received from the second handle, method <NUM> proceeds to <NUM> to activate the drive wheels. In one example, the drive wheels may be actuated at a first, constant speed. In another example, upon receiving the signals from the second handle, a speed of the drive wheels are adjusted based on the force applied on the second handle as estimated by the second force sensor contained within the second handle. While driving the drive wheels at a first speed, method <NUM> may then proceed to <NUM>, where the tube arm may continue to be driven to the parked position. If no signals are received from the second handle, method <NUM> may directly proceed to <NUM> to drive the tube arm to a parked position.

If the tube arm is in a parked position, method <NUM> may then proceed to <NUM>, as shown in <FIG>. At <NUM>, method <NUM> may determine if signals are received from the second handle after the tube arm is parked. Signals received from the second handle may include force applied to the second handle by the operator in order to manually drive the cart, which may be estimated by a second force sensor coupled to the second handle (such as second force sensor <NUM> of <FIG>). Also, the signal for moving the mobile imaging system may come from the switch (such as on the instrument panel or on the smart device communicatively connected to the imaging system) indicating a desire to move the imaging system to an end position and to move the system from one location to another. If no signal is received from the second handle or the switch, method <NUM> may proceed to <NUM>, and maintain the drive wheels in a deactivated state. The imaging system may not be moved to a different location. In one example, even if the imaging system is not being moved to a different location, the column may be actuated to a fully collapsed position via steps described in step <NUM> of this method. Following <NUM>, method <NUM> may return.

If signals are received from a second handle or the switch, method <NUM> may proceed to <NUM> to initiate actuation of the drive wheels. The signal received may be from the application of a force on the second handle and may be estimated by the second force sensor contained within the second handle, which may then send a signal to the controller to drive the drive motor, which may actuate the drive wheels.

Motion of the drive wheels may include, at <NUM>, adjusting speed of the drive wheels based on force feedback. The wheels may be driven, based on the force feedback, by the drive motor in response to force applied to the second handle. The force applied to the second handle may be sensed by the second force sensor contained within the handle, which may then send a signal to the controller, which may then actuate the wheels at a set speed via a force feedback loop based on the force applied to the second handle. In other words, the speed of the drive wheels is adjusted based on a force applied on the second hand-actuatable component as estimated via a force sensor, the speed proportional to the force applied. The control mechanism in the force feedback loop determining the power to be applied to the drive motor may be PI control, as described in relation to <FIG>. A setpoint of the controller of the drive motor may be adjusted based on the output of the second force sensor contained within the second handle and a position of the drive wheels inferred based on output of a position sensor. As an example, the position sensor may be a sensor internal to the drive motor, which may continuously measure the angular position of a shaft of the drive motor. The controller of the drive motor may receive a difference between in a setpoint power and actual power delivered to the drive motor. At the PI controller, the error may be processed and/or modified (scaled) by a proportional gain. The integral of the error may be similarly processed and/or modified (scaled) by an integral gain. One of these terms or their sum is then output to a signal. The output signal of the controller may produce the final control signal to be sent to the drive motor, which may then actuate the drive wheels at a speed determined by the force applied to the second handle. In one example, the set speed for moving the drive wheels may be proportional to the force applied to the second handle. In another example, the set (second) speed for moving the drive wheels after parking of the tube arm may be higher than the first speed at which the wheels may have been actuated while parking the tube arm.

After the motion of the drive wheels is initiated in response to a force applied to the second handle, method <NUM> may proceed to <NUM>, in which the column is driven to a fully collapsed, end position while the cart is in motion. In other words, actuating the column to the fully collapsed position may include collapsing the column from the first collapsed position to an end position while moving the drive system via actuation of drive wheels. In one example, the column may be collapsed at a constant speed regardless of the force applied on the second handle. In another example, the speed of collapsing of the column may be based on another force feedback responsive to second signals received from the second force sensor coupled to the second handle, the speed of collapsing directly proportional to the force applied on the second handle. Alternatively, the column may be collapsed even if motion of the cart is ceased, for example if the operator ceased applying force to the cart via the second handle.

Driving the column to a fully collapsed, end position may include, at <NUM>, collapsing the column to a fully collapsed, end state with the column motor and ball crew. The collapsing may include actuating the column motor via force signals received by the second force sensor contained within the second handle. Additionally or alternatively, the collapsing of the column to an end position may be initiated by a drive switch (such as drive switch <NUM> of <FIG>) on the second handle. The signals received from the drive handle switch may actuate the column motor via the controller. The column motor may then drive the ball nut via the belt drive, which may in turn drive the ball screw linearly downward as the ball screw is forced to rotate in conjunction with the rotational motion of the ball nut. The ball screw, which may rotate relative the column (e.g. may be attached to the top of the interior of the outer segment of the column by a flange bearing), may then drive the outer segment of the column linearly downwards in response to the linear downwards motion of the ball screw.

During collapsing of the column, as indicated in <NUM>, the first gas spring may provide weight compensation for the column as it collapses to a fully collapsed, end position. As the column collapses to a fully collapsed, end position, the first gas spring may further compress from the state of compression maintained under the column in a first collapsed position to a further state of compression maintained under the column in a fully collapsed, end position. As an example, the first gas spring may maintain a maximal state of compression as the column collapses to a fully collapsed, end position, which may correspond to a compression force of substantially (e.g. with a variation of <NUM>%) 1300N as mentioned in relation to <NUM>, or may reach some intermediate state of compression between a fully extended and fully compressed state.

Further, during collapsing of the column, at <NUM>, method <NUM> may proceed to expand the second gas spring. As explained in relation to <FIG>, the second gas spring is fixed at one end to the top of the interior of the inner segment of the column, and may expand downwards towards the base of the interior of the column. At the other end of the second gas spring is a pulley which the wire rope may encircle. The wire rope may be fixed to the top of the interior of the inner segment of the column, may wrap around a pulley attached to the second gas spring, exit the inner segment of the column and extend upwards into the interior of the outer segment of the column. Within the interior of the outer segment of the column, the wire rope may encircle another pulley located near the top of the interior of the outer segment of the column, may finally exit the column and attach to the base of the tube arm, and may couple to the first force sensor at the base of the tube arm. As the column collapses from a parked state to a fully collapsed, end state, the wire rope may become slacken due to the relative distance between the point of attachment of the wire rope to the tube arm and the point of exit of the wire rope from the outer segment of the column decreasing. The second gas spring, which may apply a tension force to the wire rope via a pulley, may counteract the slackening tendency of the wire by expanding in response to the reduced force applied to the pulley as the wire slackens with the collapsing of the column from the parked state to the end state.

In <NUM>, method <NUM> may proceed to determine if the column is in a fully collapsed, end position. This may involve a signal from a position sensor internal to the column motor to the controller that the column has reached an end range of motion in a fully collapsed state, which may then cause the controller to switch an internal column switch (such as column switch <NUM> of <FIG>) to a position indicating that the column is in a fully collapsed state. The column switch <NUM> may indicate to the controller that the column is in a fully collapsed state, and prevent further driving of the column motor. If the column switch is not switched into the state indicating that the column is in a fully collapsed state, then method <NUM> may proceed to <NUM>, where method <NUM> may continue to drive the column to a fully collapsed position. In one example, even if the force exerted on the second handle is removed (such as if the operator removes his hand from the second handle), the collapsing of the column may be continued until the fully collapsed state is reached. If the column is determined to be in a fully collapsed position, then method <NUM> may proceed to <NUM>.

At <NUM>, method <NUM> may discontinue driving the column while maintaining the motional state of the cart. As an example, the cart may be in motion due to actuation of the drive wheels in response to a force applied to the second handle. In this example, the cart may continue to remain in motion in response to force applied to the second handle while the column motor is deactivated in response to a signal received by the controller from the internal column switch indicating that the column has reached a fully collapsed, end position. As an alternate example, the cart may be at a standstill, e.g. due to an absence of force applied to the second handle, which may cause the drive wheels not to be driven by the drive motor. Following <NUM>, method <NUM> may return.

<FIG> shows an example timeline <NUM> for transitioning a mobile imaging system from an imaging configuration (such as during imaging a patient at a first location) to moving the imaging system to a different, second location. the transitioning includes parking a tube arm (such as tube arm <NUM>, as shown in <FIG>), and collapsing a column (such as column <NUM>, as shown in <FIG> and <FIG>) to a fully collapsed position, and then actuating drive wheels (such as drive wheels <NUM>, as shown in <FIG> and <FIG>) of the drive assembly by a drive motor (such as drive motor <NUM>, as shown in <FIG> and <FIG>) to move the mobile imaging system from the first location to the second location. The horizontal (x-axis) denotes time and the vertical markers ti-te identify significant times in the parking, column collapse and driving of the drive wheels. In this example, the angle of rotation Φ is <NUM>.

Timeline <NUM> includes plot <NUM> of the radial extension of the tube arm (such as the inner segment <NUM> of tube arm <NUM>, as shown in <FIG>), with the fully extended position indicated by a `+' on the y-axis, and the fully retracted position indicated by a '-' on the y-axis. The vertical position of the tube arm is indicated by plot <NUM>, with the maximal focal point of the tube arm indicated by a `+' on the y-axis, the parked position indicated by a '<NUM>' on the y-axis, and the minimal focal point indicated by a '-' on the y-axis. Dashed line <NUM> indicates the parked position of the tube arm, and aligns with the '<NUM>' on the y-axis of plot <NUM>. The plot <NUM> indicates the vertical position of the column, with the maximal focal point indicated by a `+' on the y-axis, the first collapsed position indicated by a ` <NUM>' on the y-axis, and a fully collapsed position indicated by a '<NUM>' on the y-axis. Additionally, dashed line <NUM> indicates the first collapsed position of the column corresponding to the parked position of the tube arm, and is aligned with the '<NUM>' along the y-axis of plot <NUM>, and dashed line <NUM> indicates the fully collapsed position of the column and is aligned with the ` <NUM>' along the y-axis of plot <NUM>. Plot <NUM> indicates a magnitude of force applied to a first handle (such as first handle <NUM> of <FIG> and <FIG>) coupled to the imaging assembly, with zero force indicated by a '<NUM>' along the y-axis, and plot <NUM> indicates a magnitude of force applied to a second handle (such as second handle <NUM> of <FIG> and <FIG>) coupled to the drive assembly with zero force indicated by a '<NUM>' along the y-axis. Plot <NUM> indicates a speed of the drive wheels, with stationary wheels indicated by a '<NUM>' along the y-axis.

Prior to time t<NUM>, the tube arm is in an imaging configuration in which the tube arm is fully radially extended, the column is fully vertically extended to a maximal focal point, and the angle of rotation Φ is <NUM>. At time t<NUM>, in response to force exerted on the first handle to transition the tube arm to the parked position, radial retraction of the tube arm is initiated. Between time t<NUM> and t<NUM>, the tube arm is radially retracted from a fully extended position to a fully retracted position. The speed of retraction of the tube arm from a fully extended position to a fully retracted position is adjusted based on based on force feedback from a first servomotor (such as first servomotor <NUM>, as shown in <FIG> and <FIG>), in response to the force applied to the first handle. At time t<NUM>, the tube arm is retracted to the fully retracted position.

At time t<NUM>, in response to continued force applied to the first handle as shown in plot <NUM>, parking of the tube arm is continued. Between time t<NUM> and t<NUM>, each of the tube arm and the column are lowered to a parked position and a first collapsed position, as indicated by plots <NUM> and <NUM>, respectively. The column and tube arm lowering is adjusted via force feedback in response to the force applied to the first handle via a column motor (such as column motor <NUM>, as shown in <FIG> and <FIG>) and second servomotor (such as second servomotor <NUM>, as shown in <FIG> and <FIG>) respectively. The force applied to the first handle from an operator (such as operator <NUM> of <FIG>) ceases at t<NUM>, as indicated in plot <NUM>. Additionally, at t<NUM>, the tube arm reaches the parked position and the column reaches the first collapsed position, as indicated by plot <NUM> intersecting dashed line <NUM> and plot <NUM> intersecting dashed line <NUM>, respectively.

After the tube arm and column parking is finished, at t<NUM>, the operator begins to apply the force to the second handle, as indicated in plot <NUM>. From t<NUM> to t<NUM>, in response to the force applied to the second handle, the column collapses from a first collapsed position to a fully collapsed position, as indicated by plot <NUM>. At t<NUM>, the column reaches the fully collapsed position, as indicated by plot <NUM> intersecting dashed line <NUM>. After the column has reached the fully collapsed position, at t<NUM>, the drive wheels are actuated by the drive motor, as shown in plot <NUM>. A speed of rotation of the drive wheels is proportional to the force applied to the second handle via force feedback, as shown through comparison of plot <NUM> and plot <NUM>.

From time t<NUM> to t<NUM>, the force applied to the second handle as shown in plot <NUM> is continually ramped up until it reaches a steady value. Concomitantly with the ramping up of force applied to the second handle as shown in plot <NUM>, speed of the drive wheels as shown in plot <NUM> is proportionally ramped up until it reaches a steady value, with the speed of the drive wheels proportional to the force applied to the second handle via force feedback. Beyond t<NUM>, the drive wheels maintain a steady speed in response to the force applied to the second handle, and the cart is transported to the second location.

<FIG> shows an example timeline <NUM> for transitioning a mobile imaging system from an imaging configuration (such as during imaging a patient at a first location) to moving the imaging system to a different, second location. the transitioning includes parking a tube arm (such as tube arm <NUM>, as shown in <FIG>), and collapsing a column (such as column <NUM>, as shown in <FIG> and <FIG>) to a fully collapsed position, while concomitantly actuating drive wheels (such as drive wheels <NUM>, as shown in <FIG> and <FIG>) of the drive assembly by a drive motor (such as drive motor <NUM>, as shown in <FIG> and <FIG>) to move the mobile imaging system from the first location to the second location. The horizontal (x-axis) denotes time and the vertical markers t<NUM>-t<NUM> identify significant times in the parking, column collapse and driving of the drive wheels. In this example, the angle of rotation Φ is <NUM>. Example timeline <NUM> illustrates the reduction in time in going from an imaging configuration to transporting the mobile imaging system when the parking of the tube arm and collapse of the column are enacted concomitantly with driving the mobile imaging system, as compared to the example timeline <NUM> of <FIG>.

Timeline <NUM> includes plot <NUM> of the radial extension of the tube arm (such as the inner segment <NUM> of tube arm <NUM>, as shown in <FIG>), with the fully extended position indicated by a `+' on the y-axis, and the fully retracted position indicated by a '-' on the y-axis. The vertical position of the tube arm is indicated by plot <NUM>, with the maximal focal point of the tube arm indicated by a `+' on the y-axis, the parked position indicated by a '<NUM>' on the y-axis, and the minimal focal point indicated by a '-' on the y-axis. Dashed line <NUM> indicates the parked position of the tube arm, and aligns with the '<NUM>' on the y-axis of plot <NUM>. The plot <NUM> indicates the vertical position of the column, with the maximal focal point indicated by a `+' on the y-axis, the first collapsed position indicated by a '<NUM>' on the y-axis, and a fully collapsed position indicated by a '<NUM>' on the y-axis. Additionally, dashed line <NUM> indicates the first collapsed position of the column corresponding to the parked position of the tube arm, and is aligned with the ` <NUM>' along the y-axis of plot <NUM>, and dashed line <NUM> indicates the fully collapsed position of the column and is aligned with the ` <NUM>' along the y-axis of plot <NUM>. Plot <NUM> indicates a magnitude of force applied to a first handle (such as first handle <NUM>, as shown in <FIG> and <FIG>) coupled to the imaging assembly, with zero force indicated by a '<NUM>' along the y-axis, and plot <NUM> indicates a magnitude of force applied to a second handle (such as second handle <NUM>, as shown in <FIG> and <FIG>) coupled to the drive assembly with zero force indicated by a '<NUM>' along the y-axis. Plot <NUM> is of the speed of the drive wheels, with stationary wheels indicated by a '<NUM>' along the y-axis. Dashed line <NUM> indicates a first threshold speed of the drive wheels, and aligns with the `+' along the y-axis of plot <NUM>. The first threshold speed is a pre-calibrated speed at which the drive wheels may be rotated upon exertion of force on the second handle during parking of the tube arm.

Prior to time t<NUM>, the tube arm is in an imaging configuration in which the tube arm is fully radially extended, the column is fully vertically extended to a maximal focal point, and the angle of rotation Φ is <NUM>. At time t<NUM>, in response to force exerted on the first handle to transition the tube arm to the parked position, radial retraction of the tube arm is initiated. From t<NUM> to t<NUM>, the tube arm position, as shown in plot <NUM>, is radially retracted from a fully extended position to a fully retracted position. The speed of retraction of the tube arm from a fully extended position to a fully retracted position is adjusted based on based on force feedback from a first servomotor (such as first servomotor <NUM>, as shown in of <FIG> and <FIG>), in response to the force applied to the first handle. At time t<NUM>, the tube arm is retracted to the fully retracted position.

At time t<NUM>, in response to continued force applied to the first handle as shown in plot <NUM>, parking of the tube arm is continued. Between time t<NUM> and t<NUM>, each of the tube arm and the column are lowered to a parked position and a first collapsed position, as indicated by plots <NUM> and <NUM>, respectively. The column and tube arm lowering is adjusted in response to the force applied to the first handle via a column motor (such as column motor <NUM>, as shown in <FIG> and <FIG>) and second servomotor (such as second servomotor <NUM>, as shown in <FIG> and <FIG>) respectively via force feedback, with the downward speed of the tube arm and the column proportional to the force applied to the first handle. At t<NUM>, an operator (such as operator <NUM> of <FIG>) ceases to apply force to the first handle as shown in plot <NUM>, and the column and tube arm continue to translate linearly downward at the same speed.

While the tube arm and column parking is in progress, such as while the tube arm and column continue to linearly translate downward proportionally to the force applied to the first handle, at t<NUM>, the operator applies a force to the second handle, as shown in plot <NUM>. From t<NUM> to t<NUM>, in response to the force applied to the second handle, the drive wheels ramp up to the first threshold speed, as shown in plot <NUM>. Since parking of the tube arm is in progress, between time t<NUM> and t<NUM>, regardless of the force applied to the second handle, the speed of the drive wheels is maintained at the first threshold speed, as indicated by plot <NUM> intersecting dashed line <NUM>.

At t<NUM>, the tube arm reaches the parked position and the column reaches the first collapsed position, as indicated by plot <NUM> intersecting dashed line <NUM> and plot <NUM> intersecting dashed line <NUM>, respectively. After the first collapsed position has reached, between t<NUM> to t<NUM>, in response to continued application of force to the second handle, the column continues to collapse to a fully collapsed position at a higher speed than during the collapse from the maximal focal point to the first collapsed position. The increase in the speed of collapse of the column is indicated in plot <NUM>. In alternate examples, the collapsing of the column is carried out at a constant speed from the maximal focal point to the fully collapsed (final) position. Additionally, upon completion of parking, at t<NUM>, the speed of the drive wheels is increased from a first threshold speed to a second speed, as shown in plot <NUM>, is the second speed being proportional to the force applied the second handle.

From time t<NUM> to t<NUM>, the force applied to the second handle as shown in plot <NUM> is continually ramped up until it reaches a steady value. Concomitantly with the ramping up of force applied to the second handle as shown in plot <NUM>, speed of the drive wheels as shown in plot <NUM> is proportionally ramped up until it reaches a steady value, with the speed of the drive wheels proportional to the force applied to the second handle via force feedback. Beyond t<NUM>, the drive wheels maintain a steady speed in response to the force applied to the second handle, and the cart is in a transport mode. In this way, in the example shown in <FIG>, by starting to drive the drive wheels while the tube arm is being parked and the column is being collapsed, the time for transitioning the mobile imaging system from the imaging configuration at a first location to a different, second imaging location is reduced. The time taken for the imaging assembly to reach the second location would be shorter for the example shown in <FIG> relative to the time taken in the example shown in <FIG> where the drive wheels could be actuated after the tube arm and the column reached their respective fully retracted positions.

In this way, for a mobile imaging system including a radiation source coupled to a drive system via a tube arm and a column, responsive to user manipulation of a first hand-actuatable component the tube arm may be actuated to a parked position, and then responsive to user manipulation of a second hand-actuatable component, the column may be actuated to a fully collapsed position while moving the drive system.

A technical effect of a mobile imaging system with mechanisms for collapsing a column concomitantly with drive motion of the mobile imaging system, is to reduce the time interval during the transition from an imaging configuration of the mobile imaging system to a transport configuration of the mobile imaging system. Overall, by reducing the time between two scans at two different locations using the imaging assembly, workflow in a busy clinic/hospital may be expedited.

An example provides for a method for a mobile imaging system, including upon conditions being met for moving the mobile imaging system, collapsing a column coupling an imaging assembly to a drive system while concomitantly moving the drive system. In a first example of the method, the imaging assembly is coupled to the column via a rotatable and extendable tube arm, the column coupling the tube arm to the drive system. In a second example of the method, which optionally includes the first example, the conditions for moving the mobile imaging system includes exertion of force on a second handle coupled to the drive system or actuation of a switch by an user during or after parking the tube arm. In a third example of the method, which optionally includes one or both of the first and second examples, parking of the tube arm is initiated by exerting force on a first handle coupled to the imaging assembly. In a fourth example of the method, which optionally includes one or more or each of the first through third examples, the parking of the tube arm includes rotation of the tube arm to an origin position, retraction of the tube arm towards the column to a fully retracted position, and driving the tube arm vertically downwards along the column. In a fifth example of the method, which optionally includes one or more or each of the first through fourth examples, each of the rotation of the tube arm, the retraction of the tube arm, and the driving of the tube arm vertically is adjusted based on a force feedback responsive to first signals received from a first force sensor coupled to the first handle or the tube arm. In a sixth example of the method, which optionally includes one or more or each of the first through fifth examples, the retraction of the tube arm is further based on a first input from a first position sensor coupled to the column indicating a radial position of the tube arm, wherein the driving of the tube arm vertically is further based on a second input from a second position sensor coupled to the tube arm indicating a vertical position of the tube arm relative to the column, and wherein the rotation of the tube arm is further based on a third input from a third position sensor coupled to the column indicating an angular displacement of the column and the tube arm relative to the origin position. In a seventh example of the method, which optionally includes one or more or each of the first through sixth examples, collapsing the column includes collapsing the column to a fully collapsed position, a speed of collapsing of the column based on another force feedback responsive to second signals received from a second force sensor coupled to the second handle. In an eighth example of the method, which optionally includes one or more or each of the first through seventh examples, during collapsing the column, a first gas spring housed within the column is compressed to provide weight compensation while a second gas spring housed within the column is expanded to maintain tension in a wire rope. In a ninth example of the method, which optionally includes one or more or each of the first through eighth examples, moving the drive system includes actuating a set of drive wheels coupled to the drive system with a speed of the drive wheels adjusted based on the second signals received from a second force sensor coupled to the second handle.

An example provides for a method for a mobile imaging system including a radiation source coupled to a drive system via a tube arm and a column, the method including responsive to user manipulation of a first hand-actuatable component, actuating the tube arm to a parked position, and then responsive to user manipulation of a second hand-actuatable component, actuating the column to a fully collapsed position while moving the drive system. In a first example of the method, actuating the tube arm to the parked position includes rotating the tube arm to an origin position via rotation of the column, retracting tube arm horizontally to a fully retracted position by retracting an inner tube segment within an outer tube segment, and translating the tube arm vertically downward along the column. In a second example of the method, which optionally includes the first example, user manipulation of the first hand-actuatable component includes application of force on the first hand-actuatable component to initiate the parking of the tube arm and then releasing the first hand-actuatable component. In a third example of the method, which optionally includes one or both of the first and second examples, while actuating the tube arm to the parked position, collapsing the column by collapsing an inner column segment within an inner column segment until a first collapsed position is reached. In a fourth example of the method, which optionally includes one or more or each of the first through third examples, actuating the column to the fully collapsed position includes collapsing the column from the first collapsed position to an end position while moving the drive system via actuation of drive wheels. In a fifth example of the method, which optionally includes one or more or each of the first through fourth examples, a speed of the drive wheels is adjusted based on a force applied on the second hand-actuatable component as estimated via a force sensor, the speed proportional to the force applied.

An example provides for a system for a mobile imaging system comprising a controller storing instructions in non-transitory memory executable by the controller to: during a first condition, collapse a column coupling a tube arm and the drive system of the imaging system at a first speed while driving the drive system forward at a second speed, and during a second condition, collapse the column at the first speed while driving the drive system forward at a third speed, the third speed higher than the second speed. In a first example of the system, the first condition includes receiving a second signal from a second handle while the tube arm is being actuated from a scan position to a parked position in response to a first signal received at a first handle, and the second condition includes receiving the second signal from the second handle after the tube arm reaching the parked position. In a second example of the system, which optionally includes the first example, the parked position includes the tube arm being in a fully retracted position, aligned along the drive system, and translated to a lowest point of the tube arm along the column, and the column being retracted to a first position, and wherein upon receiving the second signal, the column is collapsed to an end, fully retracted position. In a third example of the system, which optionally includes one or both of the first and second examples, the second signal includes an estimation of force applied on the second handle, and the fourth speed is adjusted based on the estimation of the force applied on the second handle and a position of the drive system.

Claim 1:
A method for a mobile imaging system (<NUM>), comprising:
upon conditions being met for moving the mobile imaging system,
collapsing a column (<NUM>) coupling an imaging assembly to a drive system while concomitantly moving the drive system,
wherein the conditions for moving the mobile imaging system include exertion of force on a handle (<NUM>) coupled to the drive system or actuation of a switch (<NUM>) by a user, during or after parking a tube arm (<NUM>).