Brief

Create a Simulink Model for the SCARA robot depicted in figures 1 and 2. The motor specification is appended to this brief.

You will need to create a subsystem to model the motors taking into account that the inertia of Arms 1 and 2 combined is not a constant but depends upon the orientation of Arm 2

Figure 1: Side view of SCARA Robot

The inertial load experiences by motor 1 depends upon the position of the centre of mass of Arm 2 which varies with angle, a, in figure 2.

Figure 1: Top view of SCARA Robot showing relative angle, a, between Arm 1 and Arm 2

Data

The specifications of the robot parts for the simulation are: (MI = moment of inertia)

Arm 1

Mass                               m₁                0.39 kg

Centre  of  mass               COM      0.25 m along length MI  about  COM                                      10-3  kg m2

MI about motor 1 axis    0.035 kg m2

Motor 2

Mass                                     mm               0.3 kg

MI  about  axis                 0.0012 kg m2 Therefore can be treated as a point mass MI about motor 1 axis    0.075 kg m2

Both motors are M543E as shown on the data sheet

Arm 1 with Motor 2

MI about motor 1 axis    0.11 kg m2

Arm 2

Mass                                     m1                0.39 kg

Centre  of  mass               COM      0.25 m along length MI  about  COM        5 X 10^-4  kg m²

MI about motor 2 axis 0.035 kg m² Angular   range -150 o   to +150o

End Effecter

Mass                                     me                0.35 kg

MI  about  axis                 0.00007 kg m² Therefore can be treated as a point mass MI about motor 2 axis    0.09 kg m²

Arm 2 with End Effecter

Mass                                     m²                0.74 kg

Centre  of  mass               COM      0.366 m along length MI  about  COM                                      0.024 kg m2

MI about motor 2 axis    0.123 kg m²

Inertia at Motor 1

This is dependent upon the orientation of Arm 2. From figure 2, the distance, r, of the COM of Arm 2 to the axis of motor 1 can be evaluated:

r²  = (r₁  + r₂  cos a)²  + r₂² sin 2  a

= r₁² + 2r₁r₂cos²a + r₂² cos²a + r₂² sin²a

= r₁² + 2r₁r₂cosa + r₂² 

= r₁² + r₂² + 2r₁r₂ cos a

Where r₁ = 0.5 m; r₂ = 0.366 m and a is the angle of Arm 2 relative to its local coordinate system, and so:

r² = 0.384 + 0.732 cosa

And using parallel axis theorem, the MI experienced by motor 1 from Arm 2 plus the end effecter is:

I₂  = 0.024 + 0.74r² kgm²

plus the inertia of Arm 1.

Write a report describing your model and present results on a series of tests on the model. In your conclusions, present an evaluation of the model in the light of all assumptions made and what limitations they place on the model. Also evaluate the robot based on the tests and present recommendations as to the suitability of the design and choice of motors.

The report must be in the form of a standard technical report or article to include:

Abstract Introduction

Include explanations of continuous modelling, transfer functions for DC motors with references to form a literature review.

Methods

Describe your modelling technique and the structure of the model. Justify your approaches to building the model and include any relevant references. If you include a conditioner, for example a PID controller, describe the background to such an approach and the methods of tuning.

Discussion

Discuss the model and robot performance for all the tests and their implications on the real system. Explain the reasons for how motor 1 responds.

Attachment:- Assignment Brief.rar