Robot system for controlling load of machine depending on tool wear and method for controlling load of machine using the same

A robot system for adjusting a machining load depending on tool wear which performs machining on a machining target using a tool provided on a machining unit, the robot system comprising:

• a robot that is coupled to the machining unit, moves the machining unit to change a position of the tool with respect to the machining target, and has a plurality of joints;
• a support that supports the machining target and moves the machining target to change a position of the machining target with respect to the tool;
• a sensor unit that is provided on the machining unit and measures an amount of current supplied to a machining motor which operates the tool or an operation force of the tool;
• a wear measuring unit that measures an amount of tool wear based on a reduction in a weight of the tool;
• a temperature measuring unit that measures a temperature of a surface of the machining target after a period of time that the surface is brought into contact with the tool;
• and
• a controller that receives a measurement signal from the sensor unit and transmits a control signal to the robot and the support,
• wherein the controller derives a machining load value of the machining unit based on an average of a value of the measured amount of current supplied to the machining motor and a value of the operation force of the tool;
• wherein, when the machining load value of the machining unit is larger than a reference machining load value, the controller controls the robot or the support to decrease relative movement speeds of the machining unit and the machining target;
• wherein the temperature measuring unit decreases the machining load value in response to the temperature of the surface of the machining target being higher than a reference temperature stored in the controller;
• wherein the support has a jig unit that comes into contact with the machining target to support the machining target and adjusts a position angle of the machining target with respect to the tool;
• wherein the jig unit comprises a first suction portion coupled to a first suction-portion supporting portion, and a second suction portion coupled to a second suction-portion supporting portion, the first suction-portion supporting portion coupled to the first suction-portion supporting portion and the second suction portion coupled to the second suction-portion supporting portion being arranged at an end of the support and spaced apart from each other;
• the robot system further comprising a jig driving unit that is coupled to the jig unit and causes the first suction-portion supporting portion and the second suction-portion supporting portion to move and perform a tilting motion in every direction in a three-dimensional coordinate system by moving the first suction-portion supporting portion and the second suction-portion supporting portion in an up-down, a right-left, and a front-rear direction;
• and
• wherein when the jig driving unit causes the jig unit to move and perform the tilting motion, the first suction-portion supporting portion is caused to lengthen relative to the second suction-portion supporting portion, or the second suction-portion supporting portion is caused to lengthen relative to the first suction-portion supporting portion, and
• the tilting motion of the first suction-portion supporting portion and the second suction-portion supporting portion is performed while maintaining an orientation along a straight axis;
• wherein the controller has
• a position computing unit that stores three-dimensional shape data of the machining target and computes relative positions of the tool and the machining target, and
• an operation control unit that controls an operation of the robot and an operation of the support based on a position value of the tool or a position value of the machining target which are derived by the position computing unit;
• and
• wherein the controller is configured to compare an image of the machining target and the three-dimensional shape data of the machining target to correct relative positions of the tool and the machining target, the relative positions of the tool and the machining target including relative three-dimensional positions of the tool and the machining target, and an angle formed between a central axis of the tool and a normal line to a working region of the surface of the machining target.