Research Article

Friction Model of Industrial Robot Joint with Temperature Correction by Example of KUKA KR10

Algorithm 3

Pseudocode demonstrating proposed friction torque estimation technique making temperature parameter adjustment.
Inputs:
// joint angular position, deg/s
joint angular velocity, deg/s
// joint angular velocity value for temperature adjustment, deg/s
// motor temperature, °C
// time of robot’s control program executing, s
// time parameter, upon expiration of which temperature correction is
made forcibly, s
// identified parameters of friction function eq. (16)
// periodicity criterion parameter
Outputs:
// time which it takes the motor temperature to change by °C, s
// adaptation time parameter, s
// motor temperature at time , °C
// friction torque at time ,
// load torque at time ,
// temperature parameter at time , °C
// temperature correction at time , °C
// friction torque,
// ROBOT’S CONTROL PROGRAM CYCLE
while robot’s control program executing
// Temperature change monitoring cycle
if >= 1 // if motor temperature changed by °C
// time for temperature change
end if
// Temperature parameter adjustment cycle
if 0 or // compliance of heuristic periodicity criterion eq. (20)
Pause of robot’s control program executing
// rewriting temporary variable
// ascending time value to adaptation time parameter
// assigning the velocity value for the robot joint velocity
Moving to = 180.0 // joint clockwise motion
// assigning until mowing clockwise
Moving to = 0.0 // joint counterclockwise motion
// assigning until mowing counterclockwise
and calculating by eq. (8)
by eq. (18) // temperature parameter adjustment
// temperature correction calculation by eq. (19)
end if
// temperature parameter calculation online by eq. (17)
by eq. (16) // friction torque estimation online using with temperature
correction calculated after adjustment cycle
Motions of robot’s control program executing
end while