This paper investigates the design, modelling and control of a novel contactless active robotic joint using active magnetic bearing (AMB). A robot with such joint avoids dust generation, oil lubrication and friction. This makes such robot suitable for pplications in clean environments such as clean and surgery rooms. Also, such joint can be used in space robots, selfreconfiguration robots and robots with selective compliance. In
contrast to the passive joint with AMB that needs the control of 5 degree-of-freedom (DOF), the proposed joint here needs the control of 6-DOFs. The additional variable to be controlled is the
robot joint angle. Frameless, brushless, direct drive, high torque
DC motor (BLDC) is used to control the robot joint angle. A
contactless sensor for robot joint angle measurement is proposed.
The mutual interaction between the control of the BLDC motor
and the AMB is studied. Although in this paper tracking control
of the robot joint angle and stabilization of the other 5-DOFs to
their null values are carried out, it is possible to carry out tracking
control of all the 6-DOFs. This leads to enlarge the mobility of the joint from 1-DOF to 6-DOFs. Feedback linearization controller
is used to track the robot joint angle desired trajectory. State feedback controller is used to stabilize the AMB. The proposed
system is designed and simulated using CATIA and MATLAB/
Simulink. The results prove the feasibility of the proposed robotic joint from design and control view points. |
