page 348

•Examples of simulated operation in CIMStation are,

-painting

-NC code verification

-tool and fixture simulation

-Design For Manufacturing

-process planning

-composite tape layup

-composite filament layup

-spot welding

-arc welding

-material/work manipulation

-collision detection

-deburring

-inspection

-kinematic and dynamic simulation

-controller simulation

•The simulators available for the robots in the lab allow off-line programming and simula-

tions.

11.3 INTERFACING

-TTL IO

-sourcing/sinking

-serial communications

11.4 PRACTICE PROBLEMS

page 349

7.Suggest a type of robot suitable for the following tasks. Briefly explain your suggestion. a) placing pallets on rack shelving

ans. cartesian - well suited to cartesian layout of shelves. b) electronics assembly

ans. scara - will work on a flat table well.

c) loading and unloading parts from an NC mill

ans. articulated - can easily move around obstructions.

8.Suggest a type of robot suitable for the following tasks. Briefly explain your suggestion. a) a gas pump robot for placing the gas nozzle into the fuel tank.

b) for drilling holes in a printed circuit board. c) to vacuum a hotel.

3. We plan to use a pneumatic gripper to pick up a 4 by 8 sheet of glass weighing 40 lbs. Sug-

gest a gripper layout and dimensions of the cups. State any assumptions.

ans.	For stability we want to set up an array of cups. A set of 3 or 4 would be reason-
	able to help support the sheet. - I will pick 4. Now, the diameter of the cup
	should be determined. We will assume that the vacuum pressure will be 5 psi
	below atmosphere, and we will use a factor of safety of 2.
	FS( L)			= Nπ r2P
	2( 40lb)			= 4π r25psi
	4	= r	2	r > 1.128in
	--
	π

4. A vacuum pump to be used in a robot vacuum gripper application is capable of drawing a

page 350

negative pressure of 4.0 psi compared to atmospheric. The gripper is to be used for lifting stainless steel plates, each plate having dimensions of 15” by 35”, and weighing 52 lbs. Determine the diameter of the suction cups to be used for the gripper if it is decided to use two cups for greater stability. A factor of safety of 1.5 should be used in the computations.

5. Consider the following gripper design problems.

a)We plan to use a friction gripper to pick up a 50 lb iron plate. Suggest a gripper design and specify the force required.

b)Design an end effector, and describe the path planning approach for a robot unloading satellites from the space shuttle.

11.5 LABORATORY - ROBOT INTERFACING

Purpose: Basic robot interfacing

Overview:

Pre-Lab (individual):

1.Develop a program that will put down and pick up balls at two different point for both robots.

2.Test both programs on-line.

3.Plan for a mode of robot operation either one robot can deposit a ball in a center pickup point, or at their own private pickup points. (Only a single ball will be used) Each robot will have a button connected to it. If the robot button and the other robot has the button, the robot will request the ball from other robot (using an I/O line). A list of the inputs and outputs is given below. Develop a simple diagram showing outputs and inputs to connect two robots and sensors. Develop a state diagram for the operation of both robots. Rewrite the robot programs from step 1 so that they will use the inputs.

input #1 ball in my private point input #2 other robot wants ball input #3 ball request button

output #1 request ball from other robot

In-Lab (groups of 4):

page 351

1.The instructor will discuss interfacing issues.

2.Each group should do each of the three parts below in turn.

1a. Test programs on the RV-M1, and add grippers/fixtures as required 1b. Test programs on the RT-3000, and add grippers/fixtures as required 1c. Connect and test the wiring for each of the robots and the interface

2. Integrate all of the equipment for the final task.

Submit:

1.Individually developed programs for the robots.

2.Group programs for the robots and PLC.

11.6 LABORATORY - ROBOT WORKCELL INTEGRATION

Purpose: Interfacing robots to workcells using PLCs.

Overview:

Pre-Lab (individual):

1.Develop a program that will draw a square on both robots, and test them on-line.

2.Develop a program that will draw a circle on both robots, and test them on-line.

3.Develop ladder logic for a micrologix that will watch for inputs from both robots. The two inputs will indicate when either of the robot is using the drawing paper. The PLC will also have outputs connected to both robots. Each robot will have two inputs. One input will cause a circle to be drawn, the other will cause the square to be drawn. The PLC will use inputs from push-button switches to indicate when a circle or square is to be drawn. The ladder logic should share the work between the robots.

4.Combine and modify the robot programs so that they will interface to the PLC program.

In-Lab (groups of 3):

1. Each group should do one of the tasks below,

1a. Enter and test the program on the RT-3000 robot. Use a voltage source to test the program.

1b. Enter and test the program on the RV-M1 robot. Use a voltage source to test the program.

1c. Enter and test the program on the micrologix.

2.Rotate between the stations until you have done all three modules.

3.Connect the PLC and two robots electrically, and enter and test the programs.

Submit:

1.Individually developed programs for the robots and PLC.

2.Group programs for the robots and PLC.