Control Algorithms for the 7-DOF Heavy-duty Redundant Manipulators

1) PD control synchronizing with Gazebo including Gravity and Friction Compensation:

Friction compensate model: LuGre model based

2) Active stiffness control (Cartesian stiffness control):

Depend on the task's requirement (the manipulator need to be stiff or soft), we can modulate the End Effector Cartesian stiffness:

https://github.com/shinhoang88/downscale4/blob/master/src/pmaccartesianstiffness.cpp

In these videos, the EE stiffness is modulated so that it can move freely along Y-axis while it is still stiff along X and Z axes.

a) Simulation result:

b) Experiment:

3) Master-Slave teleoperation:

Master device: Phantom Omni (6-DOF)

Slave: 7-DOF heavy-duty manipulator

For doing a remote task, the manipulator can be controlled by the master device. In the task-space of the manipulator, it can avoid the obstacle using its redundancy by changing the arm angle.

a) Simulation result:

b) Experiment:

Teleoperation with position and orientation:

Changing the arm angle:

4) A New Torque Minimization Method for Heavy-duty Redundant Manipulators Used in Nuclear Decommissioning Tasks:

This propose a method to optimize the control torque of heavy-duty redundant manipulators used for dismantling nuclear power plants: Publication link (Intelligent Service Robotics Journal, June 2021): https://link.springer.com/article/10.1007/s11370-021-00369-4?fbclid=IwAR3jAI8fR9KF3hXJEAc2UAzcSdmKRs8COPxPR_UjFViFLxrrwdPMLkHMzn8

a) Simulation:

For the given straight line trajectory:

https://github.com/shinhoang88/downscale4/blob/master/src/codestraightline.cpp

For the given quarter-circle trajectory:

https://github.com/shinhoang88/downscale4/blob/master/src/codequartercircle.cpp

b) Experiments:

• Author : Phi Tien Hoang
• E-mail : phitien@skku.edu
• Organization : Robotory-SKKU-S.Korea