Lab1 Submission Form

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University of the Fraser Valley *

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10368

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Electrical Engineering

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Apr 3, 2024

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ENME 505 Winter 2023 Lab 1 – Getting Started and Basic I/O Submission Form YOUR INFORMATION Student 1 Name: Ayman Malkawi. UCID: 30117701. Student 2 Name: Harmann Dhaliwal. UCID: 30117977 Student 3 Name: Mackallum Burchell UCID: 10162528 Student 4 Name: Princy Srivastav UCID: 30069924 QArm: #8. Laptop: Type here. YOUR FEEDBACK A. How long did it take you to complete this lab? Please round to the nearest 0.25 hour increment. Type here. hours B. How would you rate the difficulty of this lab? C. Were there any aspects of this lab that you struggled with or found confusing? If so, which? Type here. D. Suggest improvements, if any. Type here. QUESTIONS Q1. What are the instantaneous and continuous current and torque limits for each joint? How long may instantaneous currents and torques be applied to any joint for? (0.5/10 marks) Base Shoulder Elbow Wrist Gripper Instantaneous Current 4.4 A 8.8 A 4.4 A 2.3 A 1.4 A Continuous Current 1.1 A 2.2 A 1.1 A 0.6 A 0.35 A Instantaneous Current 10.6 Nm 21.2 Nm 10.6 Nm 4.1 Nm 1.9 Nm Continuous 2.65 Nm 5.3 Nm 2.65 Nm 1.0 Nm 0.5 Nm Page 1 of 5

Current Instantaneous currents and torques may be applied for any joint for no more than 0.1s. Q2. What is the maximum motor temperature for any given joint? (0.5/10 marks) 50 C. Q3. Explain what is meant by this statement: “Most of the workspace of the QArm manipulator is a reachable workspace and not dexterous.” (0.5/10 marks) Most of the workspace is reachable by the QArm manipulator as it can physically reach any point within the workspace regardless of the orientation. However, the QArm manipulator is not dexterous as it can’t reach any point with any orientation. Page 2 of 5

Q4. What is the difference between position mode and PWM mode for the QArm? (1/10 marks) The position mode operates using radians to measure a joint position and uses a closed loop controller while the PWM mode uses an open loop controller to operate. Q5. Which control mode is theoretically safer, and why? (1/10 marks) The position mode is theoretically safer compared to PWM mode. In position control, the system actively measures and controls the joint positions using a closed-loop controller, continuously adjusting the motor output to achieve the desired joint positions, providing better accuracy and control. On the other hand, PWM mode operates with an open-loop controller, where the motor is driven by a pulse signal without direct feedback on the actual joint positions. Without feedback, the system may not be aware of any deviations or errors in the joint positions, leading to potential inaccuracies and lack of control, and therefore offering more risks. Q6. Do both position mode and PWM mode follow the same positive convention? For example, does commanding the base joint a positive PWM signal cause it to rotate in the same direction as commanding it a positive angle in position mode? (0.5/10 marks) Yes, both the position mode and the PWM mode follow the same positive convention. Q7. Create a schematic diagram showing the positive convention of the QArm when operating in position mode. Your diagram must clearly show QArm joints and links, with arrows indicating the direction of positive movement for each joint. (2/10 marks) Page 3 of 5

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Q8. In steps 7-13 of the lab procedure for position mode, did you notice any discrepancies between the ranges of motion described in the Concept Review and those shown in the Measurements scope when you explored the operational space of the robot? If yes, please describe. (0.5/10 marks) We noticed very little to no discrepancies. Most discrepancies did not exceed 0.01 for all joints. Q9. In theory, what voltage would you need to apply to hold the manipulator in the home position in PWM mode, with gravity and without gravity? (1.5/10 marks) In order to hold the manipulator in the home position in PWM mode with taking gravity into account, we would need to apply a negative voltage to the shoulder and the elbow. With no gravity, however, we wouldn’t need to apply any voltage in order to hold the manipulator in the home position. Q10. In relation to the previous question, discuss the need for a closed-loop controller. (1/10 marks) In figuring out the voltage needed to keep the manipulator in the home position using PWM mode, having a closed-loop controller is important. Without it, PWM mode works blindly, lacking direct feedback on where the joints are. A closed-loop controller keeps a constant eye on the actual joint positions, checks them against where they should be, and tweaks the voltage applied to fix any differences. This constant feedback is like having a watchful eye that helps keep things accurate and stable, especially when dealing with external forces or unexpected changes. Page 4 of 5

Q11. Provide at least one reason why you would develop your own position controller using PWM mode as opposed to using the built-in PID position controller. (1/10 marks) PWM signals are power-efficient, so it might be more preferable to develop a custom position controller that uses PWM mode rather than using a built-in PID position controller. In other words, PWM does not vary in voltage but rather control the rotational speed of the motor. Page 5 of 5