1. A power tool comprising:
a motor configured to drive a working element;
a power supply coupled to the motor to provide power to the motor;
a shunt circuit coupled to the power supply and the motor, the shunt circuit configured to hold a voltage of the power supply below a high voltage threshold, the shunt circuit including a shunt element and a shunt switch, the shunt switch switchable between
a conducting state, in which the shunt switch enables the shunt element to conduct current, and
a non-conducting state, in which the shunt switch prevents the shunt element from conducting current;
a controller coupled to the motor, the power supply, and the shunt circuit, the controller configured to
determine the voltage of the power supply, and
control the shunt switch based on the voltage from the power supply.
2. The power tool of claim 1, wherein the controller is also configured to control the motor.
3. The power tool of claim 1, wherein the shunt circuit is connected in parallel to the motor.
4. The power tool of claim 1, wherein the power tool further comprises a voltage divider network coupled to the controller, and wherein the controller is configured to determine the voltage of the power supply based on information from the voltage divider network.
5. The power tool of claim 4, wherein the controller being configured to determine the voltage of the power supply includes the controller being configured to
receive a digital signal from an analog-to-digital converter, the digital signal representative of the voltage from the power supply and based on information from the voltage divider network,
compare the digital signal to a regulating threshold, and
output a control signal to the shunt switch; and
wherein, if the digital signal from the analog-to-digital converter exceeds the regulating threshold, the control signal places the shunt switch in the conducting state, and if the digital signal from the analog-to-digital converter does not exceed the regulating threshold, the control signal places the shunt switch in the non-conducting state.
6. The power tool of claim 1, wherein the controller is configured to output one of the group consisting of a logic signal and a pulse-width modulated signal to control the shunt switch.
7. A method of regulating a supply voltage of a power tool, the method comprising:
determining, by a controller, whether the supply voltage of the power tool exceeds a regulating threshold; and
regulating, by a shunt switch and a shunt element, the supply voltage to prevent the supply voltage from exceeding a high voltage threshold;
wherein regulating the supply voltage includes:
placing, by the controller, a shunt switch in a conducting state in response to the determination;
dissipating energy, by a shunt element, when the shunt switch is in the conducting state thereby preventing the supply voltage from exceeding the high voltage threshold;
placing, by the controller, the shunt switch in a non-conducting state in response to the determination; and
disconnecting, by the shunt switch, the shunt element thereby preventing the shunt element from conducting current from the supply voltage.
8. The method of claim 7, further comprising
partitioning the supply voltage to output a first voltage proportional to the supply voltage, and
converting, by an analog-to-digital converter, the first voltage proportional to the supply voltage to a digital signal representative of the supply voltage.
9. The method of claim 8, wherein determining, by the controller, whether the supply voltage exceeds a regulating threshold includes comparing the digital signal representative of the supply voltage to the regulating threshold.
10. The method of claim 7, further comprising executing, by the controller, a software control loop to repeatedly determine whether the supply voltage exceeds the regulating threshold and control the shunt switch to regulate the supply voltage.
11. The method of claim 7, wherein regulating, by the shunt switch and the shunt element, the supply voltage occurs while a motor receives power from the supply voltage.
12. A power tool comprising:
a motor configured to drive a working element;
a power supply coupled to the motor to provide power to the motor;
a shunt circuit coupled to the power supply and the motor, the shunt circuit coupled in parallel to the motor, the shunt circuit including a shunt switch and a shunt element;
a voltage sensor coupled to the power supply and connected in parallel to the motor and the shunt circuit;
a controller coupled to the voltage sensor and to the shunt circuit, the controller configured to
receive a signal from the voltage sensor representative of a supply voltage from the power supply,
determine if the supply voltage exceeds a regulating threshold,
output a control signal to the shunt circuit based on whether the signal representative of the supply voltage exceeds the regulating threshold.
13. The power tool of claim 12, wherein the shunt switch and the shunt element are connected in series to each other, and
wherein the shunt switch is switchable between
a conducting state, in which the shunt circuit conducts current and
a non-conducting state, in which the shunt circuit does not conduct current.
14. The power tool of claim 12, wherein the controller is configured to
output a control signal to the shunt switch to place the shunt switch in a conducting state when the supply voltage exceeds the regulating threshold; and
output a control signal to the shunt switch to place the shunt switch in a non-conducting state when the supply voltage does not exceed the regulating threshold.
15. The power tool of claim 12, wherein the controller is also coupled to the motor, and the controller is configured to
output a motor control signal to the motor to control an operation of the motor when the motor receives power from the power supply.
16. The power tool of claim 15, wherein when the motor does not receive power from the power supply, the controller does not output the control signal to the shunt circuit.
17. The power tool of claim 15, wherein the shunt element is a resistor, and wherein the control signal to the shunt circuit is one of the group consisting of a logic signal and a pulse-width modulated signal.
18. The power tool of claim 12, wherein the shunt circuit dissipates energy from the power supply such that the power supply does not exceed a high voltage threshold.
19. The power tool of claim 12, wherein the voltage sensor includes a voltage divider network that is coupled to an analog-to-digital converter;
wherein the analog-to-digital converter is configured to convert an analog signal representative of the supply voltage from the voltage divider network to a digital signal representative of the supply voltage; and
wherein the controller determines if the supply voltage exceeds the regulating threshold based on the digital signal representative of the supply voltage.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A method for estimation of a three-dimensional location of the distal end of a medical device using a single-plane image projection, comprising minimization of at least one or more of (i) a cost function that provides a measure of deviation between a two dimensional projected orientation in an imaging plane of an estimated three dimensional orientation, and the actual orientation of the distal end of the device as visualized in the imaging plane, and (ii) a cost function that provides a measure of deviation in three dimensions between a physics model-based computationally determined device tip location, and a geometrically determined point, line or plane.
2. The method of claim 1 wherein the estimated three-dimensional orientation of the end of the medical device is calculated as a function of the length of the medical device that extends in a bending configuration within a bending plane.
3. The method of claim 1 wherein the method for estimation of the three-dimensional location of a medical device is utilized in a feedback control algorithm for improving accuracy in navigating the end of a medical device to a target area within a subject body.
4. A method estimation of a three-dimensional location of the distal end of a medical device using a single-plane image projection, comprising minimization of a weighted sum of (i) a cost function that provides a measure of deviation between a two dimensional projected orientation in an imaging plane of an estimated three dimensional orientation, and the actual orientation of the distal end of the device as visualized in the imaging plane, and (ii) a cost function that provides a measure of deviation in three dimensions between a physics model-based computationally determined device tip location, and a geometrically determined point, line or plane
5. The method of claim 4 wherein the geometrically determined point is determined as a point on a line between the X-ray source and X-ray imaging plane.
6. The method of claim 5 wherein the two-dimensional projection of the three dimensional orientation of the end of the medical device is further calculated as a function of the device’s mechanical properties.
7. The method of claim 6 wherein the mechanical properties include the modulus of elasticity, the bending moment of inertia, and the length of the bend in the medical device.
8. A method of estimation of three-dimensional localization information for a medical device distal end utilizing a two-dimensional X-ray projection image, the method comprising:
identifying the three-dimensional location of a base point from which a length of medical device bends, and a three dimensional orientation vector for the device at the base point;
defining a bending plane in which the medical device is contained;
identifying the location and orientation of the end of the medical device as projected onto a X-ray projection image;
determining a line between the X-ray source and X-ray imaging plane for use in estimating the three-dimensional location of the end of the medical device;
defining an expected two-dimensional orientation of the end of the medical device projected onto the X-ray projection image, as a function of the length of the medical device;
determining a value of the length of the medical device that minimizes the deviation between the identified two-dimensional orientation of the end of the medical device as projected onto the X-ray projection image and the expected two-dimensional orientation calculated as a function of the length of the medical device; and
determining a point on the line between the X-ray source and X-ray imaging plane that minimizes the distance between the line and a three-dimensional location of the end of the medical device calculated as a function of the selected value of the length of the medical device, to obtain a refined estimated three-dimensional location of the end of the medical device.
9. The method of claim 8, wherein the method for estimation of the three-dimensional location of a medical device is utilized in a feedback control algorithm for improving accuracy in navigating the end of a medical device to a target area within a subject body.
10. The method of claim 8 wherein the expected two-dimensional orientation of the end of the medical device is further calculated as a function of the device’s mechanical properties.
11. The method of claim 10 wherein the mechanical properties include the modulus of elasticity, the bending moment of inertia, and the length of the bend in the medical device.
12. The method of claim 8 wherein the two-dimensional x-ray image is a projection image in an x-ray imaging system
13. The method of claim 8 wherein the method of estimation comprises using a transfer function for the medical device.
14. The method of claim 13 wherein the transfer function relates output parameters comprising local shape and local orientation at a number of points along the device to input parameters comprising pull wire tensions.
15. The method of claim 13 wherein the transfer function relates output parameters comprising local shape and local orientation at a number of points along the device to input parameters comprising magnetic field distributions.
16. The method of claim 13 wherein the transfer function relates output parameters comprising local shape and local orientation at a number of points along the device to input parameters comprising applied voltages.
17. A method of estimation of three-dimensional localization information for a medical device distal end utilizing a single plane X-ray image the method comprising:
(a) determining three-dimensional location of a base point, three-dimensional orientation vector for the device at the base point, and selecting one of a set of target points;
(b) determining a bending plane containing the base point and the orientation vector of step (a) and the selected target point of step (a);
(c) determining a neighborhood of the device distal end in three-dimension by finding the point on the line between the X-ray source and the device distal end projection that is closest to the bending plane of step (b); and
(d) iteratively searching over a range of device lengths to find the value of the device length extending from the base point of step (a) that best matches the projection data in the neighborhood of step (c).
18. A method for navigation of a medical device from a base point to a set of predetermined target points within the patient that comprises the method in claim 17.
19. A method of navigating a medical device through a subject comprising:
(a) a device predictive model;
(b) real-time image localization information from a single-plane imaging system; and
(c) using real-time information (b) as feedback to the device predictive model (a) to perform closed-loop controlled navigation.
20. A method of determining the position of the distal end of a medical device under the control of a remote navigation system in an operating region in a subject, the method comprising:
imaging the distal end portion of the medical device in the operating region to create a two dimensional image of the actual configuration of the medical device; and
comparing the predicted three dimensional configuration of the distal end portion based upon the operating parameters of the remote navigation system and the physical property of the device, with the two dimensional image of the actual configuration of the medical device to determine the position and orientation of the distal end of the operating region.
21. The method according to claim 20 wherein the comparison between the predicted three dimensional configuration of the medical device and the two dimensional image of the actual configuration is made with a cost function.
22. The method according to claim 21 wherein the position of a base point portion of the medical device shown in the two dimensional image is of known position in the operating region, and the predicted three dimensional configuration of the portion of the medical device distal to the base point is compared to the two dimensional image of the actual configuration of the portion of the device distal to the base point.