Fastener setting algorithm for drill driver
AssigneeBlack & Decker Inc.
InventorsWong Kun Ng, Christopher W. Shook
Life of this patent
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Abstract
An improved technique is presented for detecting when a fastener driven by a drill driver has reaches a desired stopping position. The improved techniques generally includes: sampling periodically current delivered to the electric motor; storing a sequence of current measures most recently sampled; and determining a slope for the sequence of current measures by way of linear regression. Transmission of torque to the output spindle can be interrupted based in part on the slope of the current measures.
Claims17
A method of controlling operation of a power tool having an electric motor drivably connected to an output spindle to impart rotary motion thereto, comprising:
- sampling periodically, by a controller residing in the power tool, current delivered to the electric motor;
- storing, by the controller, a sequence of current measures sampled by the controller, the sequence of current measures being stored in a memory of the power tool;
- determining, by the controller, a slope for the sequence of current measures by way of linear regression;
- and
- interrupting, by the controller, transmission of torque to the output spindle based in part on the slope of the sequence of current measures.
A method of setting a fastener in a workpiece using a power tool having an electric motor drivably connected to an output spindle, comprising:
- sampling, by a controller residing in the power tool, current delivered to the electric motor during periodic time intervals;
- storing, by the controller, a current measure for each time interval in a memory of the power tool;
- determining, by the controller, a slope for a plurality of current measures sampled by the controller, where the slope is determined by way of linear regression;
- comparing, by the controller, the slope to a minimum slope threshold;
- adjusting, by the controller, a slope counter in accordance with the comparison of the slope with the minimum slope threshold;
- evaluating, by the controller, the slope counter in relation to a fastener criteria, where the fastener criteria is indicative of a desired stopping position for a fastener being driven by the power tool;
- and
- interrupting, by the controller, transmission of torque to the output spindle when the slope counter meets the fastener criteria.
Dependencies are inferred from the claim text.