Research Proposal, Engineering and Construction
Parallel Robotic for Leg Rehabilitation
This study involves the design of a parallel robot with a novel 6 – degree-of-freedom and motion control on the basis of an adjusted dynamic disturbance rejection controller. It presents the structure and the geometrical model of a linear electromagnetic actuator as the main element of the parallel platform. It also adopts a kinematics-based motion control of the six degree of freedom, and a modified active impedance rejection controller.
- Degrees of Freedom In robotics
In Robotics, the degree of freedom (DOF) = the number of independently moving or rotating joints.
Figure 1: Illustration of 6 – Degree of Freedom
The Novel six Degrees of Freedom control system of the parallel robot will therefore have 6 independently moving points.
- Parts of the Robot
- Robotic Actuators
Robotic actuators are operated in this model by Hydraulic and Pneumatic compressors. The actuators in robots are used to generate the power for the motion of the robot joints (Clarence 2005, p. 83). Both pneumatic and hydraulic actuators power devices using moving fluids such as power-steering (transmission fluid).
In this model, sensors are used to study and control the motion of the arm in different positions. It uses linear encoders. The sensors make robots intelligent with the aid of a Visual Sensors (Rankers 1997, p. 38).
3.3.Electric Motors (DC Servomotors)
The electric motors in this model playing a vital role as an actuator in the 6 degrees of freedom parallel robots. It delivers high controllability with minimal requirement of maintenance. The electric motor used in this model is the DC Servomotors.
- Variants Fields
There are other related fields of study used in this project, including kinematics, mechatronics and Impedance control.
In Robotics, we apply Kinematics in driving methods of computing the various positions and orientations of the end-effectors of the manipulators in relation to the manipulator, being functions of the joint variables (Bishop 2006, p. 39).
Figure 2: Joint Variables
Motion control for high level mechatronics is applied in this model as the major technology. The generation of robust motion control is represented as function of rigidity and as a base for practical implementation. The targets of these movements are parameterized by controlling of stiffness. However, the strength of system in motion demands high level of stiffness for the controller.
- Impedance Control
Impedance control in this model controls the position and the force of the moving parts by regulating the end effectors’ mechanical impedance. This is achieved by contacting the manipulators’ environments using springs and dampers.
Figure 3: Illustration of the Motions
Figure 4: Model of a Leg
Figure 5: Actuators and Effectors
Every serial chain in this model has two revolutionary joints and one prismatic joint. In the specific plane systems, the joining screw mutual to the 2 revolving joints axes. Actuators in the model produce a special force along screw S1 and S3. The manipulator is a single unit when the axes of the mutual screws intersect is parallel. In this position, the actuators are not able to resist moments about the points of intersection; neither can it resist a perpendicular force to the three axes (Schmidt et al 2014, p. 56).
Figure 6: Model of the Manipulator
Figure 7: Impedance Control in 6 Joints
- Intelligent Controller
Figure 8: Architecture of the Robot
The robot manipulator operates by studying and applying therapy during the leg rehabilitation. As of patient reacts, the intelligent controller assesses the condition (Onwubolu 2005, p. 49). These conditions are observed by sensing the position and the magnitude of the force applied.
Figure 9: Leg Rehabilitation
Schmidt R M, Schitter G, Rankers A & Eijk J 2014, The Design of High Performance Mechatronics – 2nd revised edition. IOS Press.
Bishop R H 2006, Mechatronics: an introduction. CRC Press, 2006.
Clarence D W 2005, Mechatronics: an integrated approach. CRC Press.
Onwubolu, G C 2005, Mechatronics: principles and applications. Butterworth-Heinemann.
Rankers, A M 1997, Machine Dynamics in Mechatronic Systems. University Twente.