Polarworks As

Skogsrud, Simen Svale

Chappel, Alexandre

Fosker, Hans

Boe-wiegaard, Thomas

Westvang, Even

Thomas Boe-Wiegaard

Simen Skogsrud

Even Eidsten Westvang

Hans Fosker

Alexandre Chappel

Simen Svale Skogsrud

Even Westvang

Described is a method and device of a computational motion engine iteratively computing a numerical 'jerk,' the motion derivative of acceleration, using real-time feedback from a system under motion control, to reach both a desired position and desired velocity of a next waypoint. Output from the motion engine is only desired acceleration, which is then passed to a motor driver, free of intermediate computations of either position or velocity. A second, inside feedback loop maintains desired acceleration or torque at the motor shaft based on the acceleration output of the motion engine, which may use non-linear correction tables. Waypoints comprising both position and velocity are inputs to the motion engine. Time to next waypoint is computed rather than provided as an input. Optimization of moves to the next waypoint is based on smoothest velocity change during the move. Embodiments include mechanical, two-axis SCARA arm motion systems.

Method of iterative motion control

A device and method of iterative motion control is described using a non-linear table in a feedback loop to convert a desired acceleration input to motor drive outputs, where the motor is part of a controlled motion system. The table may be a two- or three-dimensional table additionally responsive to the current system state, such as shaft speed, position, or phase angle. The motor may be a two-coil stepper motor where the corrected non-linearity serves the purpose of maintaining desired toque. Inputs may be waypoints comprising both a target position and target velocity. The motion system may use an inverted SCARA arm. Up to three non-linear correction tables may be used: a first corrects motor steps to a more accurate shaft angle; a second corrects motor drive signals to achieve desired torque; a third correct motor drive signals responsive to shaft speed. Tables may be generated by a series of motion passes using a fixed shaft offset angle for each pass.

Device and method of motion control

A machine tool incorporating two angular axes as an inverted SCARA arm and a vertical, linear Z-axis, is described. A build surface on which a 3D object may be additively built is rotated around a lambda axis and also revolved around a theta axis. Embodiments are described that: (i) are free of belts, pulleys, cables and other soft drive mechanisms; (ii) place all three axis motors below a base plate; (iii) direct drive the build surface from shafts of a lambda and theta motor; (iv) are free of a rectangular box frame; (v) use angle sensors mounted directly on motor drive shafts; (vi) measure and compensate for build surface skew; (vii) incorporate a single element for both Z-axis support and a bearing surface. Both device and method embodiments are claimed.

Machine tool

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Easton, CT, United States of America

Thomas Boe-Wiegaard