Search

EP-4734823-A1 - SYSTEM AND METHOD FOR DETECTING AND COMPENSATING TREMORS

EP4734823A1EP 4734823 A1EP4734823 A1EP 4734823A1EP-4734823-A1

Abstract

A hand-held personal care device has an actuator for implementing a personal care function, which generates a motion of a personal care element. Motion of the personal care device is sensed, and the presence and direction of tremor movements is detected. An actuator drive signal is adapted so as to provide at least partial cancellation of the tremor.

Inventors

  • JOHNSON, MARK, THOMAS
  • GERHARDT, Lutz, Christian
  • VAN DEN DUNGEN, WILHELMUS, ANDREAS, MARINUS
  • MENA BENITO, MARIA ESTRELLA
  • RMAILE, Amir, Hussein

Assignees

  • Koninklijke Philips N.V.

Dates

Publication Date
20260506
Application Date
20240620

Claims (15)

  1. 1. A hand-held personal care device comprising: a handle (14); an actuator (16) for implementing a personal care function which generates a motion of a personal care element; a drive signal generator for generating a drive signal for driving the actuator; a sensor (20) for generating a sensor signal which depends on motion of the personal care device; and a processing arrangement (22), configured to: detect tremor vibrations from the sensor signal and thereby detect the presence of tremor and direction information in respect of the tremor; and adapt the actuator drive signal thereby to provide at least partial cancellation of the tremor.
  2. 2. The device of claim 1 , wherein the motion of the personal care element generated by the actuator comprises a rotation about a rotation axis in combination with a rocking of the rotation axis.
  3. 3. The device of claim 2, wherein the processor is configured to adapt the actuator drive signal to provide asymmetry in the speed and/or distance of rocking of the rotation axis on opposite sides of a default axis.
  4. 4. The device of any one of claims 1 to 3, wherein the actuator comprises a motor.
  5. 5. The device of claim 4, wherein the drive signal generator comprises an H-bridge circuit and the processor is configured to generate a set of control signals for control units of the H-bridge circuit.
  6. 6. The device of any one of claims 1 to 5, further comprising a tremor compensation mass, wherein the actuator is for driving the personal care element and for driving the tremor compensation mass.
  7. 7. The device of any one of claims 1 to 6, wherein the sensor (20) comprises a sensor for sensing an actuator drive current.
  8. 8. The device of any one of claims 1 to 6, wherein the sensor (20) comprises a motion sensor.
  9. 9. The device of claim 8, wherein the sensor (20) comprises a vibration sensor in the form of a microphone or single axis accelerometer.
  10. 10. The device of any one of claims 1 to 9, wherein the processing arrangement comprises a band pass filter arrangement for detecting the tremor vibrations.
  11. 11. The device of any one of claims 1 to 9, wherein the processing arrangement comprises a neural network detect tremor vibrations.
  12. 12. The device of claim 11, wherein the neural network is supplied with a spectrogram of the sensor signal for a continuous range of frequencies up to at least double the personal care function vibration frequency.
  13. 13. The device of any one of claims 1 to 12 comprising a powered toothbrush
  14. 14. A method of compensating for tremors during use of a hand-held personal care device, which device implements a personal care function comprising driving motion of a personal care element using an actuator, wherein the method comprises: generating a drive signal for driving the actuator; sensing motion of the personal care device; detecting tremor vibrations from the sensed motion and thereby detecting the presence of tremor and direction information in respect of the tremor; and adapting the actuator drive signal thereby to provide at least partial cancellation of the tremor.
  15. 15. A computer program comprising computer program code means which is adapted, when said program is run on a computer, to implement the method of claim 14.

Description

SYSTEM AND METHOD FOR DETECTING AND COMPENSATING TREMORS FIELD OF THE INVENTION This invention relates to the detection of tremors when using a hand-held device, and the compensation for such tremors. BACKGROUND OF THE INVENTION Tremor is defined as a rhythmical, involuntary oscillatory movement of a body part. Tremors are the result of involuntary alternating contractions of reciprocally innervated muscles. Tremors are the most common movement disorder symptom, especially in the elderly population. Tremors are likely to hamper many basic self-care activities, which require a good amount of motor coordination such as brushing, shaving, bathing etc. These activities are often referred as Activities of Daily Living (ADLs). This can lead to a major change in daily routine, absenteeism from work or even psychological issues. Essential tremor (ET) is the most common cause of action tremor, with an estimated prevalence worldwide of 1 percent overall and approximately 5 percent in adults over the age of 60 years. The incidence of ET increases with age, although childhood and early adulthood presentations do occur, especially when ET is familial. In context of oral health, poor motor coordination can lead to poor brushing quality, which can lead to suboptimal oral hygiene, which ultimately can lead to oral diseases. Therefore, it would be important in such cases to provide some means to minimize the physical disability due to tremors so that a person can perform the required physical activity with minimum discomfort. The most common method for diagnosis of tremors is analysis of a patient’s history and thorough physical examination along with targeted neurological assessment. The physical examination for tremor involves assessment of different characteristic of tremors such as affected body parts, position of body part, relation with body movements (at rest; during action) and frequency of tremors. Such characterization helps in grouping tremors according to their pathophysiology and aetiology, which in turn is highly relevant for choosing the most promising treatment option for tremors. The characteristic of different tremors and how they can be detected are discussed below. Orthostatic tremor This is a postural tremor in the torso and lower limbs while standing, and it may also occur in the upper limbs. It is suppressed by walking. The tremor is high frequency (14 to 20 Hz) and synchronous among ipsilateral and contralateral muscles. Physiologic tremor This is a predominantly bilateral, symmetrical action tremor. The tremor is again high frequency (10 to 12 Hz), with known causes (e.g., medications, hyperthyroidism, hypoglycemia). Essential tremor This usually presents as a bilateral postural tremor of the hands in a frequency range 6 to 12Hz, followed by a kinetic and resting component. Parkinsonism Tremor This is predominantly at rest and is asymmetrical. Usually, it does not produce head tremor. It has a frequency range 4 to 6 Hz. Cerebellar tremor This is a postural, intention, or action tremor. It has a relatively low frequency in the range 3 to 4 Hz and is associated with ataxia and dysmetria. Writing tremor This is not evident in other tasks requiring coordination, only during writing. It is considered a variant of focal hand dystonia (writer’s cramp). It has no specific frequency range. Psychogenic tremor This is an exclusion diagnosis. Symptoms vary in severity, depending on the subject’s emotional state associated with stressful life events. Entrainment is a change in frequency of the tremor in adaptation to voluntary movements, such as a regular movement in the contralateral limb. It has not specific frequency range. An accelerometer-based technique has been proposed as a proxy to measure and quantify tremors. In addition to detecting tremors, it is known to attempt to compensate for the movement caused by tremors when a user holds a hand-held device, such as a spoon, cup or toothbrush. This typically involves driving a mass in an opposite direction to a tremor movement, thereby to create an impulse in a direction which causes damping of the tremor movement. However, this requires additional mass and associated drive components to be added to the device. There is therefore a need for a simpler tremor compensation approach. Anupam Pathak et. al., “A non-invasive handheld assistance device to accommodate essential tremor; A pilot Study” Movement Disorders vol. 29, no. 6, 27 May 2014 pp, 838 - 842 discloses a study of active cancellation of tremor. The tremor cancellation senses a direction of tremor and uses a motion-generating platform to provide cancellation. WO 2020/205557 discloses an anti-tremor device, having a sensing unit for sensing tremor and a rotary control system which controls an inertia to eliminate or reduce the tremor. WO 2016/133621 discloses a system for measuring tremor, having an inertial measurement unit within a handle of a hand-held tool. SUMMARY OF THE INVENTION The invention