1.6 PRACTICE PROBLEMS
1. a) What are some basic functions expected on a robot teach pendant
b) Describe how a computer can help avoid debug robot programs without a robot being used
2. Write a short program to direct a robot to pick up and put down a block. Assume the points have already been programmed with the teach pendants.
a) Write program for the IBM 7535.
b) Write program for the Seiko RT-3000.
c) Write program for the Mitsubishi RV-M1.
3. We plan to use a pneumatic gripper to pick up a 4 by 8 sheet of glass weighing 40 lbs. Suggest a gripper layout and dimensions of the cups. State any assumptions.
4. A vacuum pump to be used in a robot vacuum gripper application is capable of drawing a 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.
6. What is the workspace for each of the robots below, and can the robots reach all positions and orientations in the workspace?
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.
9. Why are 5 axis enough for some robotic applications (eg. welding) and all NC milling operations?
10. You have been asked to write a program for a robot (you can choose either the Seiko RT-3000 or Mitsubishi RV-M1). The program is to pick up a part at point T1, move to point T2, and then load the part into a pallet. The robot should then return to point A to pick up then next part. This should continue until the pallet is full.
T1 = (300, 300, 20)
T2 = (-300, 300, 0)
Pallet has 6 rows and 7 columns
Pallet origin T3 = (300, 0, 0)
Pallet end of row T4 = (350, 0, 0)
Pallet end of column T5 = (300, 60, 0)
11. An IBM 7535 industrial robot is to be used to unload small 1 lb. cardboard boxes (5” by 4” by 1”) from a conveyor, and stack them in a large cardboard box (20” by 8” and 2” deep). After the large box is loaded, it will be removed automatically and replaced with an empty one. The conveyor will be controlled by a robot output, and it will be stopped when an optical sensor detects a small box. When the box is full the conveyor will be stopped and a light turned on until an unload button is pushed. The entire system uses a start and stop button combination. The stop button is not an e-stop, but it will stop the cycle after the small box is placed in the large box.
a) Layout the position of the conveyor, sensor, large box and robot so that all positions can be reached. Indicate critical points of objects.
b) Design a robot gripper to pick up the boxes.
c) Develop a flow chart for the robot operations.
d) Write an AML program for the flowchart.
12. Repeat the previous problem for the Seiko RT-3000 robot.
13. Given the scenario below, find the minimum angular resolution of the rotating sensor.
- the robot has +/- 0.5” accuracy
- the pallet can slide +/- 0.1” on the belt
- the driving motor is continuous, and can be run to any angle
- the rotating sensor is an incremental encoder, every rotation of some small angle it issues a pulse. But, because of the construction of the device, it has a minimum resolution for angular measurements
- the robot must be able to touch the part to pick it up
- the tool on the end of the robot is a 1” magnet, and it must be able to touch the part completely to pick it up.
- pulley size is 10” dia.
14. The IBM 7535 robot arm moves its TCP to point (-450, 250)mm at speeds programmed by ‘payload(5)’ and decelerates from the resultant speed to zero in 0.5 seconds. The tool has a mass of 1.5 kg with its center of gravity at 3cm from the TCP and transfers a mass of 4kg with its C.G. at 5cm from the TCP.
a) determine the inertia torque about the theta1 axis showing all correct units
b) compare the value in a) with a maximum inertia torque estimated from decelerating a 6kg mass from 1100mm/s to zero in 0.5 sec.
c) Estimate the combined error at the CG of the load due to theta1 and theta 2 resolution
15. Consider a double jointed manipulator as shown below. It is subjected to a loading at the tip of 8 lbs, and works in a heated environment (i.e. T0(room temp.) = 60°F and T1 (working temp.) = 80°F.
a) Determine the elongation of the manipulator.
b) Determine the total linear deflection of the manipulator.
c) Determine the total final accuracy of the manipulator of the tip of the manipulator.
16. For the robot pictured below, assume the that a maximum payload of 10kg is specified. The joints are controlled by stepper motors with 200 steps per revolution. Each of the joints slides, and the gearing is such that 1 revolution of the stepper motor will result in 1” of travel. What is the accuracy of the robot?
17. Consider a double jointed manipulator as shown below. It is subjected to a loading at the tip of 8 lbs, and works in a heated environment (i.e. T0(room temp.) = 60°F and T1 (working temp.) = 80°F.
a) Determine the elongation of the manipulator.
b) Determine the total linear deflection of the manipulator.
c) Determine the total final accuracy of the manipulator of the tip of the manipulator.
