The basic data and operating requirements are provided below. List any assumptions that you are making for additional data or operating conditions than the specified values.

Robot Configuration

• Wheeled robot with four wheels (two driven wheels in front, two rear wheels non- powered).
• Robot equipped with two manipulators – referred to as Link1 (mounted to base platform), Link2 (joined to Link1).
• Robot mobility powered by one motor, transmitted via gearing to the driven wheels. Each manipulator is powered by its own motor.
• Robot operating on flat to slight incline, carrying a rated payload (see Robot Design Data Table, below) from one location to another and returning to the original location, repeating this pattern as per the number of trips per hour mentioned.
• Robot manipulators are constructed of the specified material and given cross-sections as provided in the Available Equipment and Material Tables, below.

Robot Design Data Table

Robot weight (does not include payload)	60	kgs
Max weight of payload	12	kgs
Typical distance travelled (one way)	45	m
Time for travel – based on cycle time (max) (one way)	50	s
Number of trips per hour	5
Peak velocity allowed	1.5	m/s
Type of operating surface	concrete
Maximum time to achieve rated velocity	10	sec
Surface Friction Coefficient Crr	0.015
Max gradient in operating surface	2.5	degrees
Motor efficiency – typical	90	%
Drive train efficiency	75	%
Resistance factor (for typical wheel)	1.1
Rated voltage of battery	12	V
Minimum hours of battery operation (between recharges)	2	hrs
Incremental power for both manipulator motors combined (as a portion of the drive motor power requirement)	10	%

For Simplicity of Calculation the Following Assumptions May Be Made

1. Link2 weight includes the weight of the gripper at the end of Link2.
2. Load inertia effect for motor sizing can be assumed to be minimal.
3. The torque at the wheels can be assumed to be a single value for the motor sizing calculation (they do not need to be calculated separately for each driven wheel).

Available Equipment and Material Tables

Wheel Sizes Available – Radius (Metres)

0.12

0.15

0.20

Motor Configurations Available at 750 rpm (Torque)

1.2 N.m

1.5 N.m

2.2 N.m

Gear Sets Available (Teeth Ratio of the Driving/ Driven Gear)

12/120

10/80

8/56

Material Data for Manipulator Links

Material for Links: Mild steel with a density of 7500 kg/m³ and Youngs Modulus of 210 GPa.

	Link1	Link2
Cross Section	Square hollow section – 70mm outer width, 50mm inner width	Square hollow section – 50mm outer width, 40mm inner width
Length of Link	0.9 m	0.6 m
Motors Weight (Driving Link)	8 kg*	6 kg
Maximum Deflection Allowed (With Respect To their Base Point)	40 mm (from base of Link1 to tip of Link1)	25 mm (from joint 2 – starting point of Link2)

(* Note: The motor driving Link1 is located on the base platform of the robot, not mounted on a link.)

Q1

Calculate the torque required by the robot to move and achieve the rated velocity.

Robot weight (does not include payload)	60	kgs
Max weight of payload	12	kgs
Typical distance travelled (one way)	45	m
Time for travel – based on cycle time (max)	50	s
Number of trips per hour	5
Peak velocity allowed	1.5	m/s
Type of operating surface	concrete
Maximum time to achieve rated velocity	10	sec
Friction Coefficient Crr	0.015
Max gradient in operating surface	2.5	degrees
Motor efficiency – typical	90	%
Drive train efficiency	75	%
Resistance factor (for typical wheel )	1.1
Rated voltage of battery	12	V
Minimum hours of battery operation (between recharges)	2	hrs
Incremental power for both manipulator motors combined (as a portion of the drive motor power requirement)	10	%

Wheel Sizes Available – Radius (Metres)

0.12

0.15

0.20

Motor Configurations Available at 750 rpm (Torque)

1.2 N.m

1.5 N.m

2.2 N.m

(20 marks)

A1

Student answer:

F1

Assessor feedback:

Assessor feedback:

Q2

Provide answers for the following:

1. Specify the wheel diameter that you have selected for the robot wheels and explain why you chose that dimension. (You may use data from your answer to Q1.)
2. For the wheel diameter that you selected, calculate the velocity of the robot wheels.

(5 marks)

A2

Student answer:

F2

Assessor feedback:

Assessor feedback:

Q3	Provide answers for the following: From the wheel speed, determine the reduction required from the standard motors which are provided in the table, above. Identify the gear set required based on the reductions. Calculate the torque required from the motor.	(6 marks)
A3	Student answer:
F3	Assessor feedback:	Assessor feedback:

Q4	Provide answers for the following: Determine the energy losses for this robot configuration. Calculate the actual power that needs to be developed by the motors to meet the torque at the wheel.	(4 marks)
A4	Student answer:
F4	Assessor feedback:	Assessor feedback:

Q5	Calculate the battery sizing required to power the robot for the duty cycle specified. Assume no power losses when the robot is on standby (not operating).	(10 marks)
A5	Student answer:
F5	Assessor feedback:	Assessor feedback:

Q6	What was my overall reflection on this module/unit, and what insights or lessons did I gain that will help me grow in my career?	(5 marks)
A6	Student answer:
F6	Assessor feedback:	(marks awarded)

Answer rating: 100% (QA)

SOLUTION Here are answers to the questions Q1 Calculate the torque required by the robot to move and achieve the rated velocity To calculate ... View the full answer