Patent ID: 9193074
Filing Date: 2015-11-24
Classification: B25J

Abstract:
1. A multi-joint robot comprising: a robot mechanical unit having at least one arm; a gas spring arranged on the arm; and a controller which controls the robot mechanical unit, wherein the gas spring comprises a cylinder, compressible inert gas enclosed within the cylinder and a piston rod configured to slide in the cylinder, the gas spring being configured as a gas balancer for reducing a load of a servomotor which drives the arm, and wherein the controller has a function to obtain a reference current value of a servomotor for driving the arm at a reference point in time when the servomotor is energized and controlled; obtain an object current value of the servomotor at a point in time, which is different from the reference point in time, when the servomotor is energized and controlled under the same operating condition as the reference point in time; calculate a difference between the reference current value and the object current value; and calculate an amount of decrease in inner pressure of the compressible inert gas of the gas spring, based on the difference.