Closed-loop identification of an industrial robot containing flexibilities

Abstract

Closed loop identification of an industrial robot of the type ABB IRB 1400 is considered. Using data collected when the robot is subject to feedback control and moving around axis one linear black-box and physically parameterized models are identified. A main purpose is to model the mechanical flexibilities and it is found that the dynamics of the robot can be well approximated by a model consisting of three-masses connected by springs and dampers. It also found that the results of the identification depend on the properties of the input signal. Keywords: identification, robotics, flexible arms Closed Loop Identification of an Industrial Robot Containing FlexibilitiesMånsÖstring, Svante Gunnarsson * , Mikael Norrlöf Department of Electrical Engineering, Linköping University, SE-58183 Linköping, Sweden AbstractClosed loop identification of an industrial robot of the type ABB IRB 1400 is considered. Using data collected when the robot is subject to feedback control and moving around axis one linear black-box and physically parameterized models are identified. A main purpose is to model the mechanical flexibilities and it is found that the dynamics of the robot can be well approximated by a model consisting of three-masses connected by springs and dampers. It also found that the results of the identification depend on the properties of the input signal.

Bayesian position estimation of an industrial robot using multiple sensors

“…The coefficients are then estimated from an identification experiment. See for instance [20]. Here it will be assumed that the transmission can be described by a two mass system and that the manipulator is rigid.…”

“…The linearization is calculated around the predicted estimate of the states. Since the measurement relation uses (20) for the acceleration component, there are many complicated nonlinear expressions. The linearization is therefore performed symbolically so it is straightforward to implement in the EKF given an estimate of the state variable,x t|t−1 .…”

Identification of two-mass mechanical systems using torque excitation: Design and experimental evaluation

“…H IGH-PERFORMANCE ac electric drives are replacing pneumatic and hydraulic actuators or dc motor drives in modern machineries-such as injection molding machines [1], machine tools [2], industrial robots [3]-due to their energy efficiency, compact size, and flexible control algorithms. These machineries often consist of several moving or rotating masses coupled together with flexible mechanical transmissions (e.g., belts, gearboxes, long shafts), leading to mechanical resonances.…”

“…As examples, a rolling-bearing damage [13] and gearbox faults [14], [15] can be identified using electric drives. The identification routines, proposed for parameter estimation of two-or multi-mass mechanical systems, can be roughly divided to parametric methods [3], [6], [16]- [20] and nonparametric methods [16], [21]- [24]. The nonparametric methods use the frequency-domain characteristics of the system, while, in the parametric methods, the parameters of the two-mass system transfer-function polynomials are estimated in the time domain.…”

“…The rotor-speed response of the driving motor is measured. Because the rotor-speed response is noisy, the discrete-time OE model is used in identification, in accordance with [3]. The main contributions of this paper are: 1) An indirect closed-loop method is proposed for identification of two-mass mechanical system.…”