An encoder includes a scale and a sensor. The scale has first and second absolute patterns. The sensor includes a light source, and first and second absolute light receivers. The first and second absolute light receivers receive light from the first and second absolute patterns, respectively. The first absolute light receiver receives light from the first pattern and includes first and second light receiving elements. Each first light receiving elements outputs a first signal with a first phase. Each second light receiving elements outputs a first signal with a second phase. The first and second light receiving elements are arranged alternately. The second absolute light receiver includes third and fourth light receiving elements. Each third light receiving element outputs a second signal with the first phase. The third and fourth light receiving elements are arranged alternately. Each fourth light receiving element outputs a second signal with the second phase.

An encoder includes a scale and a sensor. The scale has first and second absolute patterns. The sensor includes a light source, and first and second absolute light receivers. The first and second absolute light receivers receive light from the first and second absolute patterns, respectively. The first absolute light receiver receives light from the first pattern and includes first and second light receiving elements. Each first light receiving elements outputs a first signal with a first phase. Each second light receiving elements outputs a first signal with a second phase. The first and second light receiving elements are arranged alternately. The second absolute light receiver includes third and fourth light receiving elements. Each third light receiving element outputs a second signal with the first phase. The third and fourth light receiving elements are arranged alternately. Each fourth light receiving element outputs a second signal with the second phase.

An encoder includes a scale and a sensor. The scale has first and second absolute patterns. The sensor includes a light source, and first and second absolute light receivers. The first and second absolute light receivers receive light from the first and second absolute patterns, respectively. The first absolute light receiver receives light from the first pattern and includes first and second light receiving elements. Each first light receiving elements outputs a first signal with a first phase. Each second light receiving elements outputs a first signal with a second phase. The first and second light receiving elements are arranged alternately. The second absolute light receiver includes third and fourth light receiving elements. Each third light receiving element outputs a second signal with the first phase. The third and fourth light receiving elements are arranged alternately. Each fourth light receiving element outputs a second signal with the second phase.

An encoder includes a scale and a sensor. The scale has first and second absolute patterns. The sensor includes a light source, and first and second absolute light receivers. The first and second absolute light receivers receive light from the first and second absolute patterns, respectively. The first absolute light receiver receives light from the first pattern and includes first and second light receiving elements. Each first light receiving elements outputs a first signal with a first phase. Each second light receiving elements outputs a first signal with a second phase. The first and second light receiving elements are arranged alternately. The second absolute light receiver includes third and fourth light receiving elements. Each third light receiving element outputs a second signal with the first phase. The third and fourth light receiving elements are arranged alternately. Each fourth light receiving element outputs a second signal with the second phase.

A method, according to the present invention, of adjusting control parameters used in a control apparatus of an electric motor includes the steps of: computing a first frequency characteristic (Step 1); computing a present speed-proportional gain range (Step 2); computing a present mechanical-system characteristic constant (Step 3); computing a present proportional gain range (Step 4); computing a secular characteristic (Step 5); computing a secular speed-proportional gain range (Step 6); computing a secular proportional gain range (Step 7); and selecting proportional gain values (Step 8).

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.

A method, according to the present invention, of adjusting control parameters used in a control apparatus of an electric motor includes the steps of: computing a first frequency characteristic (Step 1); computing a present speed-proportional gain range (Step 2); computing a present mechanical-system characteristic constant (Step 3); computing a present proportional gain range (Step 4); computing a secular characteristic (Step 5); computing a secular speed-proportional gain range (Step 6); computing a secular proportional gain range (Step 7); and selecting proportional gain values (Step 8).

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.

A method, according to the present invention, of adjusting control parameters used in a control apparatus of an electric motor includes the steps of: computing a first frequency characteristic (Step 1); computing a present speed-proportional gain range (Step 2); computing a present mechanical-system characteristic constant (Step 3); computing a present proportional gain range (Step 4); computing a secular characteristic (Step 5); computing a secular speed-proportional gain range (Step 6); computing a secular proportional gain range (Step 7); and selecting proportional gain values (Step 8).

A control device, a method of controlling the control device and recording medium are provided. An adherence performance of all of a plurality of servo control systems is improved. A controller predicts a response of a first servo control system corresponding to a corrected trajectory and corrects a first command value or generates a second inverse kinematics trajectory using the predicted response.