Playback system grinding robot

A playback system grinding robot for controlling the movement of an abrasive tool in a horizontal plane and for grinding the surface of a workpiece to be ground, and having a dual degree-of-freedom of control in a polar coordinate system, comprising in combination:

• a support means including a main vertical rotary axis and a secondary vertical axis;
• a first arm having a first end and a second end, said first arm being supported rotatably about said main axis at said first end by said support means;
• said first arm having a head at said second end;
• a second arm having a first end and a second end, said second arm being pivotably attached to said head of said first arm at said first end of said second arm;
• said second arm being pivotable about a vertical axis;
• a third arm having a first end thereof connected for rotation with a revolution shaft, and a linkage means connected between an intermediate portion of said second arm and a second end of said third arm, for driving said second arm;
• said revolution shaft about which said third arm rotates having an axis of rotation which is vertically disposed, said revolution shaft being disposed adjacent to and having its axis parallel with said main vertical rotary axis;
• said second end of said second arm having a head;
• said head of said second arm having a vertical axis;
• an abrasive tool connected to said head axis of said second arm so as to be freely turnable to different directions;
• a holder mounted rotatably and vertically movably at said head end of said second arm and projecting downwardly for a predetermined length from a lower surface of said second arm, said holder having said abrasive tool fixed thereto at a lower end of said holder;
• an air cylinder disposed on an upper surface of said head end of said second arm and biasing said holder downwardly by a piston rod;
• a first servomotor for turning said first arm around said main axis;
• a second servomotor for rotating said revolution shaft and turning said second arm;
• a positional data generating means for generating positional data indicating a horizontal movement position of said abrasive tool;
• a memory means for storing said positional data;
• said positional data generating means including a first rotary encoder for detecting a turning angle of said first arm and a second rotary encoder for detecting a rotating angle of said revolution shaft;
• whereby a direct teaching to said memory means occurs by manually moving said holder attached with said abrasive tool along the locus to be travelled, on the surface of the workpiece, thereby taking in angle pulses from said first and second rotary encoders and sequentially counting and storing the positional data of the abrasive tool on the horizontal plane;
• a playback means for playing back said positional data to control movement of said abrasive tool;
• and a robot control circuit for generating the angle pulses corresponding to said positional data so as to drive said first and second servomotors and conducting an automatic playback grinding operation on the taught locus.