Project

# Title Team Members TA Documents Sponsor
23 Clickers For ZJUI Undergraduate Mk Ⅱ
 Benlu Wang
Luozhen Wang
Suhao Wang
Zhenyu Zhang
 design_document1.pdf
final_paper1.pdf
final_paper2.pdf
final_paper3.pdf
proposal1.pdf
proposal2.pdf
 Fangwei Shao
# TEAM MEMBERS
Zhenyu Zhang (zhenyuz5)
Benlu Wang (benluw2)
Luozhen Wang (luozhen2)
Suhao Wang (suhao2)

# PROBLEM
I-clicker is an educational tool employed by ZJUI to fulfill the digital demands of the classroom, serving as a class check-in and answer device. However, the existing transmitters and receivers face limitations in terms of their capacity to handle substantial loads, high signal delay, and signal loss. These constraints hinder the device's ability to effectively meet the requirements of a large number of users. Additionally, the current I-clicker system fails to cater to the preferences of students who prefer to utilize mobile applications for participation.

# SOLUTION OVERVIEW
This project aims to design and develop a comprehensive classroom response system that supports multiple frontends, including web browsers, mobile applications (iOS and Android platforms), WeChat Mini Programs, and physical Clickers. Additionally, a user-friendly web-based interface will be created to provide teachers with intuitive management functionalities. The system incorporates a high-concurrency unified backend equipped with distributed and in-memory databases, offering caching capabilities to efficiently handle large volumes of student submissions, as well as perform evaluation and statistical analysis. The project also entails the shell design and implementation of a distributed and energy-efficient transmission system for the physical Clickers and their receivers to address the limitation of signal loss.

# SOLUTION COMPONENTS
This project encompasses four essential components: frontend development, backend optimization, hardware improvement, and enclosure design.

## Frontend Development:
For instance, we can develop a user-friendly web-based interface using popular frontend technologies such as HTML, CSS, and JavaScript. This interface can be accessible through standard web browsers on various devices, offering teachers the flexibility to manage the voting result.
Additionally, as part of the meticulous frontend development process, the project aims to provide students with diverse options to interact with the voting system. As we possess a physical clicker as part of our system, our commitment lies in ensuring compatibility and functionality between the mobile app and the physical clicker, allowing both to transmit signals that can be effectively processed by the receiver.
Furthermore, if time permits, the project can also develop WeChat Mini Programs. These lightweight applications within the WeChat ecosystem provide a seamless and familiar voting experience for students who prefer to use the WeChat platform.


## Backend Development:
By constructing a high-concurrency unified backend, fortified with distributed and in-memory databases, the system will be empowered with caching capabilities capable of effectively managing the influx of student submissions.
In this scenario, the system can employ a distributed database system, such as Apache Cassandra or Amazon DynamoDB, to handle the storage and retrieval of student submissions. By distributing the data across multiple nodes, the system can benefit from increased scalability and fault tolerance.
To further enhance performance, an in-memory database, such as Redis or Apache Ignite, can be utilized as a caching layer. This allows frequently accessed data, such as student responses and evaluation results, to be stored in memory for faster retrieval, reducing the need to repeatedly access the distributed database.

## Hardware Improvement:
Recognizing the significance of enhancing reception capabilities, the project dedicates attention to the development of a distributed and energy-efficient transmission system for the physical Clickers and their corresponding receivers. The voting system incorporates a System-on-Chip (SoC) solution to handle both the transmitter and receiver functionalities. The SoC, such as ESP32 or STM32, integrates microcontroller capabilities and offers built-in wireless connectivity options like Wi-Fi or Bluetooth. The SoC transmitter facilitates the transmission of votes from the voting devices to the central system using its dedicated peripherals for user input. The SoC receiver receives the transmitted votes, establishes a reliable connection with the voting devices through Wi-Fi or Bluetooth, decodes the received data, and manages the voting information effectively. This integrated approach utilizing SoC technology ensures seamless bidirectional communication, efficient data transmission, and reliable vote collection within the voting system.

## Enclosure Design:
In addition to the technical facets, the project encompasses the meticulous design of an enclosure, using 3D printing technology, specifically tailored for the physical Clickers. This component embraces the principles of aesthetics, functionality, durability, ergonomics, and user-friendliness. By prioritizing these design considerations, the enclosure aims to enhance the overall user experience, ensuring that the physical Clickers are comfortable to handle and operate.

# CRITERION FOR SUCCESS

Concurrency Handling: Build a high-concurrency backend system for efficient processing of large volumes of student submissions concurrently.

Affordability: Develop cost-effective i-clickers to promote widespread adoption and accessibility for students.

Support for Multiple Frontends: The system should be designed to support multiple frontends, including mobile applications, web browsers, and dedicated software, ensuring compatibility, seamless interaction, and consistent user experience across various platforms.



Signal Stability: Ensure reliable signal reception in challenging environments and minimize signal loss within classrooms.

Distributed and Energy-Efficient Transmission: Implement a distributed transmission system with low-power consumption to optimize device performance and energy efficiency.

Aesthetic Design: Create visually appealing i-clicker shell designs that are widely accepted and facilitate customization through 3D printing.

# DISTRIBUTION OF WORK
Benlu Wang: Responsible for designing and developing web-based interfaces, mobile applications, and WeChat Mini Programs to provide a range of frontend options for students to interact with the voting system.

Zhenyu Zhang: Tasked with optimizing the backend infrastructure, including the development of a high-concurrency unified backend, distributed and in-memory databases, and efficient data management for seamless operations.

Luozhen Wang: Responsible for designing and creating customized enclosures for the physical Clickers using 3D printing technology, ensuring an aesthetically pleasing, functional, and user-friendly design.

Suhao Wang: In charge of improving the hardware components of the voting system, particularly focusing on the development of a distributed and energy-efficient transmission system using System-on-Chip (SoC) technology.

VTOL Drone with Only Two Propellers

Yanzhao Gong, Jinke Li, Tianqi Yu, Qianli Zhao

Featured Project

# **TEAM MEMBERS:**

- Yu Tianqi(tianqiy3)

- Li Jinke(jinkeli2)

- Gong Yanzhao(yanzhao8)

- Zhao Qianli(qianliz2)

# **TITLE: VTOL DRONE WITH ONLY TWO PROPELLERS**

# **PROBLEM:**

Nowadays, drones, as an important carrier of new technology and advanced productivity, have become an vital part of the development of new aviation forms. They have been used in many different areas such as military, civilian, commercial and so on. Traditional drones like helicopters have shortcomings in flight speed while fixed-wing aircraft require a runway for takeoff and landing. Vertical takeoff and landing (VTOL) aircraft not only have helicopters' assessibility and flexbility to take off and land in small spaces, thus they can fly to destinations that are not easily accessible by traditional aircraft, such as remote areas or areas with poor infrastructure; the design of VTOL also allows for faster deployment and response times which is especially important in emergency situations where every second counts. Addtionlly, simpler construcrtion of this drone not only reduces over all cost but requires less energy in longer flight time. Overall, VTOL aircraft offer a level of flexibility and efficiency that traditional aircraft cannot match, making them a valuable tool in a variety of industries, including transportation, military, and emergency services.

# **SOLUTION OVERVIEW:**

We plan to design a small VTOL UAV with a wingspan of about one meter to achieve both vertical takeoff and landing and horizontal flight like a fixed-wing aircraft by means of a horizontal tail and rotatable propellers located at the ends of the mean wings. Such two flight modes and the transition between them require a very precise perception and adjustment of the aircraft's attitude. To do this, we need a high frequency motherboard and some gyroscopic sensors to receive and process the aircraft attitude information and make feedback adjustments. This places high demands on the control section, and also on the mechanical side to ensure structural rigidity, reduce unpredictable jitter in the wings and other components, and thus reduce additional attitude adjustments. What's more, we also need to give more thought to the design of the rotatable propeller section. It is important to reduce the inertia of the rotating part while reducing the complexity of the structure and making it more reliable. For our aircraft, the arrangement of internal electronics and storage space has a huge impact on the center of gravity. While designing the aircraft structure with sufficient strength. We also consider the arrangement of the location of each electronic component, the heat dissipation of electronic components, sufficient storage space, certain water resistance, easier maintenance, etc. We believe that with the cooperation of the team members from different disciplines, we can be responsible for our own sub-projects and take full consideration of the design of other sub-projects to complete the overall design.

# **SOLUTION COMPONENTS:**

**VTOL Control Subsystem:** Different from the traditional sliding mode, vertical takeoff and landing makes our drone basically get rid of the dependence on the runway. This subsystem uses the GY-521 breakout of the MPU6050 6 degree of a freedom IMU. It gives adequate measurement precision to stabilize our drone. We use Teensy 4.0 as our microcontroller and use it for robotics, audio projects and Arduino applications (Teensyduino in our drone). After we assemble all the hardware stuff, we need to write the control code in Arduino/C++ language and uploaded them to the Teensy 4.0 board using Arduino IDE. Our drone will use the rotary lift fan to realize the vertical takeoff and landing of the aircraft by relying on the torque force output of the motor according to the feedback information of the IMU.

**Power Subsystem:** The power system will provide sufficient power for the takeoff and subsequent flight of the drone. It mainly includes two motors, two electric regulators, two propellers and batteries. In our VTOL drone, we plan to use Sunnysky brushless motors V2216, KV800, which could provide a maximum force of 1360N each. And according to the working current, we choose 30A electric regulators and 7.4V batteries.

**Mechanical Subsystem:** This system is the main structure of the drone, housing the rest subsystems of the drone. It is also a vital part, providing lift force when the drone is level. It consists of wings, fuselage and tail. In our drone, we plan to use lightweight PLA to 3D print the wings and other small part and laser cut the glass fiber plate to get the fuselage. Carbon fiber rods are also used in the wing parts to support the 3D printed wings.

**Adjustment of the center of gravity Subsystem:** This subsystem consist of a gyroscope and Teensy 4.0 board, which detects the position of the drone's center of gravity in real time and tranmits the information to the board. The board calculates and transmits the porper angle to the servos, so that the drone can fly soomthly in the air.

**Feedback Control Subsystem:** This subsysteem is aimed to ensure the drone mantains a stable flight path and does not deviate from its target orientation. The system works by comparing the current and target orientation and adjusting each propeller's angle according in order toreduce any error. A PID controller is used to determine the necessary adjustments, and it is then sent to the properllers via a servo motor in order to adjust the blades angles. This process is repeated contiually as the drone is flown.

**Flight mode adjustment Subsysytem:** This subsystem contains two servo, Teensy4.0 board, drone remote control and receiver. When the UAV recives a signal to switch from vertical flight mode to horizontal flight mode, it turns the angles od servos so that a horizontal force is generated to move the UAV in the horizontal direction.

# **CRITERION FOR SUCCESS:**

- Flight performance: The drone should be able to take off and land vertically, as well as hover and maneuver smoothly in the air. It should also have a sufficient range and flight time to perform its intended function.

- Payload capacity: The drone should be able to carry the required payload, such as a camera, sensors, or delivery package, while maintaining stability and flight performance.

- Safety: The drone should be designed with safety in mind, including proper wiring, motor placement, and redundancy systems to prevent crashes or malfunctions.

- Reliability: The drone should be built with high-quality components and tested thoroughly to ensure that it operates reliably and consistently over time.

- Cost-effectiveness: The drone should be designed and built in a cost-effective manner, using affordable components and minimizing unnecessary features or complexity.

# **DISTRIBUTION OF WORK**

## ME STUDENT Yanzhao Gong:

- Print and assembly the mechanical parts of the drone.

- Participate in the design of the rotating mechanism of the two propellerso and the follow-up improvement.

## EE STUDENT Qianli Zhao:

- Adjust and control the drone propellers angle when the drone goes from vertical takeoff to horizontal flight.

- Use the gyroscope to detect and adjust the center of gravity of the drone in time.

## ECE STUDENT Li Jinke:

- Participate in the electrical design of the drone. Complete the welding, assembly and debugging of the electronic control hardware equipment of drone

- Implementation and debugging of drone vertical takeoff and landing control algorithm code

## ME STUDENT Tianqi Yu:

- The design of the fuselage part of the structure, the use of glass fiber plate, carbon fiber rods and PLA 3d printing with the design of lightweight, high-strength fuselage.

- Participated in the design of the rotating mechanism of the two propellers at the end of the wing.