Partial arc curvilinear direct drive servomotor
View Patent ↗A partial arc servomotor assembly having a curvilinear U-channel with two parallel rare earth permanent magnet plates facing each other and a pivoted ironless three phase coil armature winding moves between the plates. An encoder read head is fixed to a mounting plate above the coil armature winding and a curvilinear encoder scale is curved to be co-axis with the curvilinear U-channel permanent magnet track formed by the permanent magnet plates. Driven by a set of miniaturized power electronics devices closely looped with a positioning feedback encoder, the angular position and velocity of the pivoted payload is programmable and precisely controlled.
1. In combination: a partial arc curvilinear direct drive servomotor (PACDDS) assembly; a digital controller coupled to said PACDDS assembly to provide a drive signal to said PACDDS assembly in response to a motion command and a positioning feedback signal; and a position sensor optical encoder attached to said PACDDS assembly for monitoring reference position of a coil armature or forcer of said PACDDS assembly to the fixed encoder scale and providing said positioning feedback signal to said digital controller to enable closed-loop servomotor operation of said PACDDS assembly, wherein said PACDDS assembly comprises; a pair of parallel plates having a partial arc separated by a spacer; a first plurality of permanent magnets attached to a first of said parallel plates on an inside surface, the permanent magnets being arranged adjacent to each other in an alternating north-south pole pattern forming a first magnetic plate; a second plurality of permanent magnets attached to a second of said parallel plates on an inside surface, the permanent magnets being arranged adjacent to each other in an alternating south-north pole pattern symmetrically across from the north-south pole pattern of said first of said parallel plates forming a second magnetic plate; a moveable armature winding positioned between said first and second magnetic plates; and an encoder system having a read head mounted to said armature winding and above a curvilinear encoder scale mounted on top of said first magnetic track.
2. The combination as recited in claim 1 wherein said partial arc of said parallel plates is formed along a predetermined radius approximately 146.6 mm using one inch square magnets with a twenty-four degree (24°) magnet pitch.
3. The combination as recited in claim 1 wherein said partial arc of said parallel plates is formed along a predetermined radius approximately 194.84 mm using one inch square magnets with an eighteen degree (18°) magnet pitch.