Abstract
The invention relates to a method for generating acoustic feedback of an orthopaedic device comprising at least one electric motor (13), which has a stator (30) and a rotor (40) which can rotate about a rotational axis (50) and is coupled to a component of the orthopaedic device, which component can be moved by the electric motor (13), wherein the electric motor (13) is oscillatingly operated by repeated pole changing of at least one motor voltage, without the rotor (4) performing a complete rotation about the rotational axis (50).
Claims
1. A method for generating acoustic feedback of an orthopedic device comprising at least one electric motor comprising a stator and a rotor configured to rotate about an axis of rotation and wherein the rotor is coupled to a component of the orthopedic device which is adjustable by the electric motor, the method comprising the steps of: operating the at least one electric motor in an oscillating manner by repeated reversal of a polarity of at least one motor voltage, and rotating the rotor about the axis of rotation but without the rotor performing a complete rotation about the axis of rotation.
2. The method as claimed in claim 1, wherein a square-wave voltage, delta voltage, sawtooth voltage, sinusoidal curve voltage or a mixed form thereof is used as the at least one motor voltage during the operating step.
3. The method as claimed in claim 1 wherein the repeated reversal of the polarity of the at least one motor voltage is operated at a frequency ranging from 20 Hz to 6000 Hz.
4. The method as claimed in claim 1 wherein the at least one electric motor is operated with different polarity reversal frequencies in a time sequence and/or wherein the at least one electric motor comprises several electric motors with different polarity reversal frequencies and the several electric motors are operated simultaneously or successively.
5. The method as claimed in claim 1 further comprising changing an amplitude of the at least one motor voltage during the polarity reversal.
6. The method as claimed in claim 1 wherein the at least one electric a motor is a commutator motor, and further comprising the step of periodically reversing the polarity of the at least one motor voltage of the at least one electric motor to generate an acoustically perceptible signal.
7. The method as claimed in claim 1 wherein the at least one electric motor is a brushless DC motor, and further comprising the step of periodically changing a phase of a rotating field of the brushless DC motor to generate an acoustically perceptible signal.
8. The method as claimed in claim 1 wherein the rotor is moved in an oscillating manner by an angle of rotation of not more than 120 to generate an acoustically perceptible signal.
9. An orthopedic device, comprising: at least one electric motor comprising a stator and a rotor, wherein the rotor is rotatable an axis of rotation, and wherein the rotor is coupled to a component of the orthopedic device which is adjustable by the at least one electric motor; a control device connected to the at least one electric motor, wherein the control device is set up to repeatedly reverse a polarity of at least one motor voltage of the at least one electric motor to generate an acoustically perceptible signal, without the rotor performing a complete rotation about the axis of rotation.
10. The orthopedic device as claimed in claim 9, wherein the control device is set up to generate a polarity reversal frequency ranging from 20 Hz to 6000 Hz.
11. The orthopedic device as claimed in claim 9 wherein the control device and/or the at least one electric motor is configured such that different voltage amplitudes are present at different polarity reversal frequencies.
12. The orthopedic device as claimed in claim 9 wherein the at least one electric motor is a brushless DC motor or commutator motor.
13. The method of claim 8 wherein the angle of rotation is not more than 90.
Description
[0019] An exemplary embodiment of the invention is explained in more detail below on the basis of
[0020] FIGS. 1 to 3. The same reference signs refer to the same components. In the figures:
[0021] FIG. 1shows a schematic illustration of an orthopedic device;
[0022] FIG. 2ashows a commutator motor;
[0023] FIG. 2bshows a graph of the motor voltage over time;
[0024] FIG. 3ashows a brushless DC motor;
[0025] FIG. 3bshows a graph of the motor angle and the pole voltages over time; and
[0026] FIG. 4shows a schematic illustration of an upper limb prosthesis.
[0027] FIG. 1 shows a schematic illustration of an orthopedic device in the form of a lower limb prosthesis comprising an upper part 10 and a lower part 20, which parts are mounted on one another in an articulated manner about a pivot axis 11. In the exemplary embodiment illustrated, the upper part 10 has a prosthetic shaft which is used to receive a thigh stump. Other orthopedic devices such as upper limb prostheses and upper and lower limb orthoses are further examples of an orthopedic device. An actuator 12 is arranged between the upper part 10 and the lower part 20. In the exemplary embodiment illustrated, the actuator 12 is designed as a linearly acting actuator 12 and comprises a drive 13 in the form of an electric motor to adjust the position of the upper part 10 relative to the lower part 20. The actuator 12 may be formed, for example, as a hydraulically acting actuator and comprise a pump which is driven by the drive 13. A hydraulic fluid is pumped via the pump into a pump chamber or into a chamber closed by a piston. The piston is coupled to a piston rod mounted on the upper part 10 or lower part 20. By pumping the hydraulic fluid appropriately into the pump chamber, the piston rod is moved in one direction or another and the upper part 10 is pivoted relative to the lower part 20. This makes it possible to carry out, brake or support an extension movement or a flexion movement of the orthopedic device. As an alternative to a hydraulic embodiment of the actuator 12, it may also be of mechanical design, such that a spindle is driven via the drive 13, for example. The spindle can then be extended into and retracted from an actuator housing to bring about an extension or flexion of the orthopedic device. A control device 14 is arranged on the drive 13, the control device allowing repeated reversal of the polarity of a motor voltage of the drive 13, such that the drive carries out an oscillating movement using which an acoustic feedback is generated.
[0028] FIG. 2a shows a commutator motor. The commutator motor comprises a stator 30 which is designed as a permanent magnet with a magnetic north pole N and a magnetic south pole S. The rotor 40 is arranged between the two magnetic poles. The rotor 40 is pivotable about an axis of rotation 50 and, in the exemplary embodiment shown, is designed as a double T-rotor with two T-shaped head elements 401, which are arranged symmetrically along an axis perpendicular to the axis of rotation 50. A cylindrical commutator 70 is arranged on the rotor 40 concentrically to the axis of rotation 50, the rotor being permanently connected to the commutator. Two opposite sides of the commutator 70 have sliding contacts 60 arranged on them. Two conductive zones 701 are arranged on the outer surface of the commutator 70. The two conductive zones 701 are spatially separated from one another by way of a non-conductive zone 702. The non-conductive zone 702 extends on two opposite areas to the outer surface of the commutator 70 and thus divides the conductive zone 701 into two areas of equal size. The conductive zones 701 are each connected via a connection 703 to the rotor windings 402 which are arranged on the cylindrical portions of the two T-shaped head elements 401. In the position shown, the sliding contacts 60 make contact with the conductive zones 701. Since a motor voltage U is applied to the sliding contacts 60, an electromagnetic field is generated at the rotor via the rotor winding 402. The rotor 40 begins to rotate due to the attraction and repulsion from the permanent magnet of the stator 30. During rotation, the commutator 70 is used as a mechanical switch for reversing the polarity of the electromagnetic field at the rotor 40, such that continuous rotation is possible. A control device 14 can be used to reverse the polarity of the motor voltage U applied to the sliding contacts 60. Such a reversal of the polarity results in the rotor 40 forming an electromagnet with the opposite polarity. This causes the rotor 40 to rotate in the opposite direction. If the polarity reversal is repeated by the control device 14, in particular periodically, the rotor 40 performs an oscillating movement which can be used to generate acoustic feedback.
[0029] FIG. 2b shows a graph of the motor voltage U at a commutator motor over time. The curve K1 shows a square-wave curve of the motor voltage U over time t. At the beginning, the motor voltage is 10 volts, after 14 time units it changes abruptly to 10 volts, after another 14 time units the motor voltage jumps again to 10 volts. The polarity is reversed periodically. Aperiodic polarity reversals are also possible. A square-wave form is used here as a waveform for the polarity reversal. It is also possible to use delta, sawtooth or sinusoidal waveforms or a mixture of these. The frequency of the waveform illustrated is about 36 Hz at a time unit of t in milliseconds; other frequencies, in particular several superimposed frequencies, which lie in the hearing range of the human ear, are also conceivable.
[0030] FIG. 3a shows a brushless DC motor. In the brushless DC motor, the rotor 40 is designed as a cylindrical permanent magnet which is located concentrically within the stator 30, has a north pole N and a south pole S, and is pivotable about the axis of rotation 50. The stator 30 is designed as a cylindrical sleeve which has three inwardly projecting, cylindrical, ferromagnetic cores 301-303, on each of which a winding 304 is arranged. The cores 301-303 are arranged at an angle of 120 with respect to one another. The windings 304 of the three cores 301-303 are connected to one another via a circuit system which is not shown in any more detail. Independent motor voltages U, V, W are applied to the various windings 304 via the circuit system, such that independent electromagnets are created at the three cores 301-303. A suitable reversal of the polarity of the motor voltages over time can cause the rotor 40 to rotate about the axis of rotation 50. For example, U, V, and W are phase-shifted, sinusoidal AC voltages. If the AC voltage at the second core 302 is shifted by 120 and the one at the third core 303 by 240 in comparison with the first core 301, the rotor 40 is rotated about the axis of rotation 50 constantly in synchronization with the AC voltage. Only two or more than three cores can also be arranged on the stator 30.
[0031] FIG. 3b shows a graph of the rotor angle and the motor voltages U, V, W at a brushless DC motor over time. The curve K2 shows the course of the rotor angle over time. The rotor angle starts at 0 and first increases linearly up to a value of 90 and then drops abruptly back to the initial value of 0. This process then starts again. The curves K3, K4 and K5 show the courses of the motor voltages U, V, W over time. The motor voltages U, V, W start at different initial values and first show the course of three sinusoidal curves, each phase-shifted by 120, with an amplitude of 100 V. The first motor voltage U increases, for example, in the time window in which the rotor angle increases to 90, sinusoidally up to the maximum value of 100 V. In order to rapidly change the rotor angle to the initial value of 0, the polarity of the motor voltages U, V, W are also reversed to their respective initial value. This is only possible because the rotor 40 has only performed a small rotation. If the rotor 40 has performed a rotation of more than one rotation, it cannot reverse this rotation by a sudden reversal of the polarity, but can only be moved to its relative initial position, however, in which it has performed a rotation of 360 or an integer multiple of thereof compared to the initial position.
[0032] Irrespective of the design of the electric motor 13, it is possible, through the repeated, in particular periodic, reversal of the polarity of at least one motor voltage, to operate the electric motor 13 in an oscillating manner, without the rotor 40 performing a complete rotation about the axis of rotation 50. Advantageously, the polarity is reversed in such a way that none of the components of the orthopedic device are moved. Due to the manufacturing tolerances, the necessary clearance and the gear units or transmission devices necessarily arranged between the electric motor 13 and the common components, the rotor 40 can implement comparatively large angles of rotation of less than 120, without a relative displacement of the components taking place. In particular, the angle of rotation of less than 90 is set, whereby the rotor 40, depending on frequency and mechanics, almost does not move at all, but only generates a torque which periodically changes the sign. The movement or the change in torque is sufficient to generate acoustic feedback that the user of the orthopedic device can perceive. The acoustic perceptible signal is advantageously in a frequency range between 20 Hz and 6000 Hz.
[0033] FIG. 4 illustrates a further embodiment of the orthopedic device in the form of an upper limb prosthesis. The orthopedic device has a prosthetic shaft as upper part 10 for receiving a forearm stump and a prosthetic hand arranged distally thereto as lower part 20. Several electric motors 13 are arranged within the prosthetic hand 20, an electric motor 13 is used to move the prosthetic hand 20 relative to the prosthesis shaft 10, while several electric motors 13 are arranged within the prosthetic hand 20 which move the fingers or the thumb relative to a main body of the prosthetic hand 20 or relative to a chassis. All electric motors 13 are coupled to a control device 14 via which it is possible to reverse the polarity of the voltage of respective motors 13 repeatedly, such that the respective electric motor 13 oscillates, without the rotor of the electric motor 13 performing a complete rotation about the axis of rotation thereof.
LIST OF REFERENCE SIGNS
[0034] 10 Upper part [0035] 11 Pivot axis [0036] 12 Actuator [0037] 13 Drive [0038] 14 Control device [0039] 20 Lower part [0040] 30 Stator [0041] 301 First core [0042] 302 Second core [0043] 303 Third core [0044] 304 Winding [0045] 305 Circuit system [0046] 40 Rotor [0047] 401 Head elements [0048] 402 Rotor winding [0049] 50 Axis of rotation [0050] 60 Sliding contact [0051] 70 Commutator [0052] 701 Conductive zone [0053] 702 Non-conductive zone [0054] K1 Motor voltage over time [0055] K2 Rotor angle over time [0056] K3 First motor voltage over time [0057] K4 Second motor voltage over time [0058] K5 Third motor voltage over time [0059] N Magnetic north pole [0060] S Magnetic south pole [0061] U Motor voltage [0062] V Second motor voltage [0063] W Third motor voltage [0064] Angle of the rotor
