Force responsive power tool

A tool for operating on a workpiece, the tool comprising:

• a motion actuator configured to be coupled to a working surface to engage the workpiece;
• a controller coupled to the motion actuator to responsively vary a speed of the motion actuator and an operating speed of the working surface within the range of an initial speed and a max speed, and configured to respond to a derived force that is a function of an applied force exerted by the operator to manageably adjust pressure on the working surface to achieve a rate of work and thereby represents an amount of force an operator applies between the workpiece and the working surface, wherein the controller is further configured, under both acceleration and deceleration, to allow the operator with the applied force to manageably change simultaneously both a rate of work on the workpiece and the operating speed of the working surface according to a sensitivity profile expressing a relationship of a monotonically increasing positive slope between the derived force and the operating speed of the working surface within the initial speed and the max speed, wherein the controller is configured to:
• derive a first derived force during a first time interval;
• set a first operating speed based on the sensitivity profile;
• derive a second derived force during a second time interval;
• when the second derived force is greater than the first derived force by a first predetermined amount, adjusting to a second operating speed based on the sensitivity profile and the second derived force;
• when the second derived force is less than the first derived force by a second predetermined amount, adjusting to a third operating speed based on the sensitivity profile and the second derived force;
• and
• when the second derived force is determined to be less than the first derived force plus the first predetermined amount and greater than the first derived force minus the second predetermined amount, adjusting to a fourth operating speed based on the sensitivity profile and the second derived force.

A control system for a tool to operate on a workpiece, the control system comprising:

• a controller configured to couple to a motion actuator to responsively vary the amount of power delivered by the motion actuator to a working surface of the tool, and further configured to couple to a force detector configured to output a signal representing a derived force that is a function of an applied force exerted by an operator to manageably adjust pressure on the working surface to control an operating speed between an initial speed and a max speed and thereby represents an amount of force the operator applies between the workpiece and the working surface, wherein the controller is further configured, under both acceleration and deceleration, to receive the signal from the force detector and allow the operator with the applied force to manageably change simultaneously both a rate of work on the workpiece and the operating speed of the working surface according to a sensitivity profile that includes at least one region expressing a relationship of a monotonically increasing positive slope between the derived amount of force and the operating speed of the working surface within the initial speed and the max speed, wherein the sensitivity profile allows for variances of the motion actuator, the controller, and the force detector to be compensated for by the operator manageably adjusting workpiece pressure as necessary to get a desired speed of the working surface and the rate of work, and wherein the controller is further configured to compare the derived force with previous readings of the signal to determine if the derived force is increasing or decreasing by a predetermined threshold before varying the operating speed of the working surface.

A tool for operating on a workpiece, the tool comprising:

• a motion actuator configured to be coupled to a rotating working surface to engage the workpiece with an assembly having a non-zero inertia;
• a controller coupled to the motion actuator to responsively vary a speed of the motion actuator and an operating speed of the rotating working surface within the range of an initial speed and a max speed, and configured to respond to a derived force that is a function of an applied force exerted by an operator to manageably adjust pressure and alignment of the workpiece on the rotating working surface to achieve a rate of work and thereby represents an amount of force the operator applies between the workpiece and the rotating working surface, wherein the controller is further configured, under both acceleration and deceleration, to allow the operator with the applied force to manageably change simultaneously both the rate of work on the workpiece and the operating speed of the rotating working surface according to a sensitivity profile expressing a relationship of a monotonically increasing positive slope between the derived force and the operating speed of the rotating working surface within the initial speed and the max speed, wherein the controller is configured to compare the derived force with previous readings to determine if the derived force is increasing or decreasing by a predetermined threshold before varying the operating speed of the rotating working surface, and wherein the predetermined threshold allows for states of hysteresis with offsets from the sensitivity profile to increase stability, correct for the non-zero inertia, and allow for variations in the applied force exerted by the operator.

A method of controlling a power tool, comprising the steps of:

• deriving a first force applied by an operator to a workpiece onto a rotating working surface coupled to an assembly having a non-zero inertia during a first time interval;
• setting a first operating speed of the rotating working surface coupled to a motion actuator based on a predetermined continuous response profile expressing a relationship of a monotonically increasing positive slope between a derived force and an operating speed of the rotating working surface within an initial speed and a max speed, wherein the derived force is a function of an applied force exerted by the operator to manageably adjust pressure and alignment of the workpiece on the rotating working surface to achieve the operating speed of the rotating working surface between the initial speed and the max speed and thereby represents an amount of force the operator applies between the workpiece and the rotating working surface to allow the operator with the applied force to manageably change simultaneously both a rate of work on the workpiece and the operating speed of the rotating working surface under both acceleration and deceleration;
• deriving a second force applied by an operator onto the workpiece to the rotating working surface of the power tool during a second time interval;
• when the second force is greater than the first force by a first predetermined amount, adjusting to a second operating speed based on the predetermined continuous response profile and the second force;
• when the second force is less than the first force by a second predetermined amount, adjusting to a third operating speed based on the predetermined continuous response profile and the second force;
• when the second force is determined to be less than the first force plus the first predetermined amount and greater than the first force minus the second predetermined amount, adjusting to a fourth operating speed to the power tool based on the predetermined continuous response profile and the second force, and wherein the first and second predetermined amounts allow for states of hysteresis with offsets from the sensitivity profile to increase stability, correct for the non-zero inertia, and allow for variations in the applied force exerted by the operator.

A control system for a tool to operate on a workpiece, the control system comprising:

• a controller configured to couple to a motion actuator to responsively vary the amount of power delivered by the motion actuator to a rotating working surface of the tool with an assembly having a non-zero inertia, and further configured to couple to a force detector configured to output a signal representing a derived force that is a function of an applied force exerted by an operator to manageably adjust pressure and alignment of the workpiece on the rotating working surface to control an operating speed between an initial speed and a max speed and thereby represents an amount of force the operator applies between the workpiece and the rotating working surface, wherein the controller is further configured, under both acceleration and deceleration, to receive the signal from the force detector and allow the operator with the applied force to manageably change simultaneously both a rate of work on the workpiece and the operating speed of the rotating working surface according to a sensitivity profile expressing a relationship of a monotonically increasing positive slope between the derived force and the operating speed of the rotating working surface with in the initial speed and the max speed, wherein the controller is configured to compare the derived force with previous readings to determine if the derived force is increasing or decreasing by a predetermined threshold before varying the speed of the operating speed of the rotating working surface, and wherein the predetermined threshold allows for states of hysteresis with offsets from the sensitivity profile to increase stability, correct for the non-zero inertia, and allow for variations in the applied force exerted by the operator.

A tangible non-transitory computer readable medium for executing instructions on a computer, the medium including routines to:

• respond to a first derived force representing a first force applied by an operator from a workpiece onto a rotating working surface coupled to an assembly having a non-zero inertia during a first time interval, set a first operating speed of the rotating working surface coupled to a motion actuator based on a predetermined continuous response profile expressing a relationship of a monotonically increasing positive slope between a derived force and an operating speed of the rotating working surface within an initial speed and a max speed, the derived force is a function of an applied force exerted by the operator to manageably adjust pressure and alignment of the workpiece on the workpiece to control the operating speed of the rotating working surface between the initial speed and the max speed to allow the operator to manageably change simultaneously both a rate of work on the workpiece and the operating speed of the rotating working surface under both acceleration and deceleration;
• respond to a second derived force representing a second force applied from the workpiece onto the rotating working surface of the power tool during a second time interval;
• when the second derived force is greater than the first derived force by a first predetermined amount, adjust a second operating speed based on the predetermined continuous response profile and the second force;
• when the second derived force is less than the first derived force by a second predetermined amount, adjust a third operating speed based on the predetermined continuous response profile and the second force;
• when the second derived force is determined to be less than the first derived force plus the first predetermined amount and greater than the first force minus the second predetermined amount, apply a fourth operating speed to the power tool based on the predetermined continuous response profile and the second force, and wherein the first and second predetermined amounts allow for states of hysteresis with offsets from the sensitivity profile to increase stability, correct for the non-zero inertia, and allow for variations in the applied force exerted by the operator.

A power tool for operating on a workpiece, the tool comprising:

• a motion actuator coupled to a rotating working surface to engage the workpiece with an assembly with a non-zero inertia;
• a controller coupled to the motion actuator and configured to receive a signal of a derived force that is a function of an applied force exerted by an operator to manageably adjust pressure and alignment of the workpiece on the rotating working surface to control an operating speed between an initial speed and a max speed and thereby representing a work load force applied by an operator that the workpiece exerts on the rotating working surface, and the controller is further configured to:
• a) set a functional speed of the rotating working surface between the initial speed at a first force and the max speed at a second force based on a predetermined continuous response profile expressing a relationship of a monotonically increasing positive slope between the work load force and the operating speed of the rotating working surface within the initial speed and the max speed to allow the operator to manageably change simultaneously both a rate of work on the workpiece and the operating speed of the rotating working surface under both acceleration and deceleration;
• b) at all work load forces greater than the first force and less than the second force, lower a first rate of work at the functional speed relative to a second rate of work at the max speed at an equivalent workload force;
• and c) compare the derived force with previous readings to determine if the derived force is increasing or decreasing by a predetermined threshold before varying the functional speed of the rotating working surface, wherein the predetermined threshold allows for states of hysteresis with offsets from the sensitivity profile to increase stability, correct for the non-zero inertia, and allow for variations in the applied force exerted by the operator.