Method and system for a feedback controller for a handheld tool

A method performed by a handheld tool, the method comprising:

• measuring, with a first inertial measuring unit (“IMU”), at least an orientation of a housing of a handheld tool relative to a reference frame of Earth;
• measuring, with a second IMU, at least an orientation of an attachment arm relative to the reference frame of Earth, wherein the attachment arm extends from the housing of the handheld tool;
• storing the orientation of the housing and the orientation of the attachment arm in a memory;
• controlling, with a processing logic, a first motion generating mechanism and a second motion generating mechanism to move the attachment arm relative to the housing based on the measured orientation of the housing and the measured orientation of the attachment arm to stabilize motion of a user-assistive device attached to a distal end of the attachment arm;
• when one or more shared orientation axes of the housing, the attachment arm, or a user assistive device attached to the attachment arm are measured as misaligned, determining that a misalignment error has resulted from sensor drift, wherein the one or more shared orientation axes comprise axes of components, including the housing, the attachment arm, or the user assistive device, that are physically constant relative to each other despite the components moving relative to each other along other axes;
• and
• correcting the misalignment error prior to generating one or more motor commands for driving the first or second motion generating mechanisms.

A non-transitory machine readable storage medium having instructions stored thereon, which when executed by a processing system, cause the processing system to perform a method comprising:

• measuring, with a first inertial measuring unit (“IMU”), at least an orientation of a housing of a handheld tool relative to a reference frame of Earth;
• measuring, with a second IMU, at least an orientation of an attachment arm extending from the housing of the handheld tool relative to a reference frame of Earth;
• storing the orientation of the housing and the orientation of the attachment arm in a memory;
• controlling, with a processing logic, a first motion generating mechanism and a second motion generating mechanism to move the attachment arm relative to the housing based on the measured orientation of the housing and the measured orientation of the attachment arm to stabilize motion of a user-assistive device attached to a distal end of the attachment arm;
• when one or more shared orientation axes of the housing, the attachment arm, or a user assistive device attached to the attachment arm are measured as misaligned, determining that a misalignment error has resulted from sensor drift, wherein the one or more shared orientation axes comprise axes of components, including the housing, the attachment arm, or the user assistive device, that are physically constant relative to each other despite the components moving relative to each other along other axes;
• and
• correcting the misalignment error prior to generating one or more motor commands for driving the first or second motion generating mechanisms.

A handheld tool, comprising:

• a handle including a first sensor that measures at least an orientation of the handle relative to a reference frame of Earth;
• a first motion generating mechanism disposed within the handle;
• an attachment arm having a second sensor disposed thereon that measures at least an orientation of the attachment arm relative to the reference frame of Earth, wherein the attachment arm extends from the handle and is coupled with the first motion-generating mechanism;
• a second motion generating mechanism coupled with the first motion-generating mechanism to collectively move a user-assistive device attached to a distal end of the attachment arm in at least two degrees of freedom;
• and
• a controller coupled to the first and second sensors and the first and second motion generating mechanisms, the controller including logic that when executed causes the handheld tool to perform operations including:
• measuring orientations of the housing and the attachment arm;
• when one or more shared orientation axes of the housing, the attachment arm, or the user assistive device are measured as misaligned, determining that a misalignment error has resulted from sensor drift, wherein the one or more shared orientation axes comprise axes of components, including the housing, the attachment arm, or the user assistive device, that are physically constant relative to each other despite the components moving relative to each other along other axes;
• and
• correcting the misalignment error prior to generating one or more motor commands for driving the first or second motion generating mechanisms.