Robotic Systems

Question 1

What is the definition of a robot?

Answer 1

An actuated mechanism programmable in two or more axes, with a degree of autonomy, moving with its environment, to perform intended tasks

Question 2

What are the two main ways we can catagorise robots?

Answer 2

• Field of Application e.g. Medical / Industrial
• Mobile and Stationary Robots

Question 3

What are the 6 levels of autonomy that we could see in a car?

Answer 3

0. No autonomy
1. Basic assistance (Cruise Control)
2. Steer and Acceleration under driving monitoring
3. The driver doesn’t need to monitor in certain conditions
4. The car can drive on its own in most situations
5. Fully autonomous (No driver needed)

Question 4

What are the programming methods we can use for robots?

Answer 4

• Offline: The robot trajectory and program is pre-computed based on kinematics
• Teaching: The operator will use the teaching pendant to move the robot and save specific points
• Lead-Through: The operator will manipulate the robot directly which will memorize the trajectory

Question 5

What is the difference between Task space trajectory and Joint space trajectory?

Answer 5

Task space trajectory has a set path and moves directly between the two points
Joint space trajectory has set points, and then the path is determined by the system each time

Question 6

What are the two types of joints?

Answer 6

• Revolute Joints: Limits the motion between two points to a rotation
• Prismatic Joints: Limits the motion between two points to a translation

Question 7

What is meant by degrees of freedom?

Answer 7

The number of independent relative motions between the links of the robot

Question 8

What is the formula for the Degrees of Freedom?

Answer 8

DoF = m(N-1-J) + The sum of the mobilities of joint i

m = 6 for 3D robots, and 3 for planar robots
N = Number of links (including the ground
J = Number of joints

Question 9

What type of robot is a SCARA robot?

Answer 9

RRP

Question 10

What are the two types of coordinates do we use for robotics?

Answer 10

• Joints coordinates: Give the rotation or position of every joint of the robot. We denote q the vector of joint coordinates
• Cartesian coordinates: Gives the position and orientation of the end effector in the reference frame

Question 11

What is the aim of forward kinematics?

Answer 11

To determine the end effector’s position and orientation, knowing the joint coordinates and link length

Question 12

What is the aim of inverse kinematics?

Answer 12

To determine the joint coordinates from the knowledge of the end effector’s cartesian position and orientation

Question 13

What do static studies of robotics analyse?

Answer 13

The effect of gravity, the backlash, the joint or link flexibility, the payload and torque equilibrium

Question 14

What do dynamic studies of robots consider?

Answer 14

The inertial effect due to accelerations

Question 15

What is the control resolution of a robot?

Answer 15

The capability of the robot’s positioning system to divide the range of the joint into closely spaced points, called addressable points

Question 16

What is the formula for the Control Resolution?

Answer 16

CR = R / (2^n - 1)

R = Actuator Range
n = Number of bit storage register devoted to a particular part

Question 17

What is the repeatability of a robot for it’s movements?

Answer 17

r = Plus or minus 3 * Standard deviation of the robot error distribution

Question 18

What is the accuracy of a robot?

Answer 18

It’s the difference between the speciied position and the actual position

Ac = CR/2 + r

Question 19

What are the names of the Tait Byran angles?

Answer 19

Roll, Pitch and Yaw