SCARA+ System: Bin Picking System Of Revolution-Symmetry Objects

Jin, G., Yu, X., Chen, Y., Li, J. (2023), SCARA+ System: Bin Picking System Of Revolution-Symmetry Objects, IEEE Trans. Ind. Electron.

Overview

Inspired by the fact that the DoF (degree of freedom) of the RS (revolution-symmetry) pose is exactly the same as adding one DoF to SCARA, we develop a SCARA+ configuration of a SCARA with an additional revolute joint, and explore the possibility of integrating it with a 3D camera to achieve the bin picking of RS objects. To this end, we first discuss the SCARA+ kinematics with the modified DH (Denavit-Hartenberg) parameters. Then, to calibrate the additional DH and the hand-eye parameters in the kinematics, we construct an axis-point model and provide an iterative solution without singularity. Finally, comprehensive experiments verify the superiority of the SCARA+ system. When compared to the state-of-the-art systems, our system achieves a significant efficiency improvement with relatively lower costs. It has also been successfully applied in the spinning industry for practical bobbin loading. This repository mainly contains the codes for simulations and experiments in the article.

Figure: Configuration of SCARA+ system.

Usage

Setups

MATLAB R2020a without any dependencies.

Main Instruction

To run the DH+ and hand-eye calibration, call

[R,tw,pw,thetap,rnti,k_num] = Alg(Ri,ti,ppi)

where

• Ri (3x3xn): the rotation matrix of SCARA pose (n is the measurement number),

• ti (3xn): the translation vector of SCARA pose,

• ppi (3xn): the detected position of the axis point,

• R (3x3): the rotation matrix of the hand-eye transformation,

• tw (3x1): the generalized translation vector of the hand-eye transforamtion (unit: mm),

• pw (2x1): the first two dimensional positions of the axis point (unit: mm),

• thetap (1x1): the joint angle of DH+ parameters (unit: degree),

• rnti (3x3): the runtime (unit: seconds).

• k_num (3x1): the iterative number.

Simulations

• File simu1 is the forward Kinematics simulation;
• File simu2 is the inverse Kinematics simulation;
• File simu3 is the calibration simulations for singular and non-singular models;
• File simu4 is the calibration simulations for different measurement numbers and different noises;

Experiments

• File exp1 is the calibration experiment;
• File caliData is the raw data of the calibration experiment.

Video

Video record for the calibration and pick-up is on http://youtu.be/aI9nByyTc4Y.

Figure: The calibration configuration.

Figure: Snaps of three trials for bobbin picking using SCARA+ system.

Contact

Gumin Jin, Department of Automation, Shanghai Jiao Tong University, Shanghai, jingumin@sjtu.edu.cn