Project

# Title Team Members TA Documents Sponsor
8 Hybrid Actuation Arm Exoskeleton
 Alan Lu
Rubin Du
 Haocheng Bill Yang proposal1.pdf
**Team**

Alan Lu -- jialin8

Rubin Du -- rd25

**Problem**

Lifting and carrying heavy objects is a common but physically demanding task faced in both personal and industrial environments. Whether it is a person at home carrying groceries or a logistics worker handling cargo, repetitive lifting puts stress on the musculoskeletal system and can result in fatigue, reduced productivity, and even long-term injuries. Existing exoskeleton solutions often focus on industrial use, but they suffer from limited backdrivability, high weight, or overly complex designs that prevent practical everyday use. A lightweight, safe, and efficient solution is needed to reduce the physical burden of lifting while maintaining user freedom of movement.

**Solution**

Our team proposes the development of a wearable exoskeleton system designed to assist users in lifting objects of up to 10 kilograms with minimal effort. The system employs a hybrid actuation strategy that combines the strengths of both a BLDC motor and a servo motor: the BLDC provides the torque required for large-angle lifting motions, while the servo supplies stable holding torque to maintain the lifted position without excess energy drain. The BLDC goes through a 64:1 planetary gear set to amplify torque, and the servo motor goes through a moveable linkage system to create sufficient mechanical advantage to further reduce the load on the motor. A detachable drivetrain allows the user to disengage the actuation system, enabling free arm movement when lifting support is not required. The skeleton itself is lightweight, manufactured using carbon-fiber-reinforced nylon (PA-CF), ensuring durability and comfort. This modular design starts with elbow actuation and can be scaled to include shoulder actuation, broadening its application.

**Solution Components**

**Subsystem 1: Mechanical Skeleton and Drivetrain**
- Lightweight PA-CF composite structure, under 3 kg excluding the battery.
- Hybrid drivetrain using BLDC with planetary gear for motion and servo motor for holding.
- Drivetrain disengagement mechanism for free arm movement.
- Moveable armor integrated with a linkage system on the drivetrain that elaborately moves upper limb armor to avoid structural interference.

**Subsystem 2: Actuation and Power System**
- Actuated by BLDC + servo combination for efficiency and safety.
- Powered by a 6S LiPo battery (~200 Wh), providing several hours of continuous assistance.
- Custom PCB with DC-DC buck converters for peripheral loads and power distribution.
- Thermal management through ventilation and optional forced convection.

**Subsystem 3: Control and Signal Processing**
- Joint actuation regulated through PID controllers.
- User intent detected via EMG sensors integrated into the arm.
- Signal conditioning pipeline: Kalman filter → Chebyshev low-pass filter → controller input.
- Optional manual override via a simple forearm-mounted control panel.
- Microcontroller and peripheral signals integrated on a customized PCB/FPGA.

**Subsystem 4: Peripherals**
- Armor ambient light will be integrated into the shell of the skeleton for aesthetics.
- Ventilation port openings will be controlled by microservos to ensure good heat dissipation.
- A manual control panel will be placed on the lower limb skeleton to include manual operations and emergency switches.
- TPU-based soft pads inside the skeleton to provide a comfort experience for the user.

**Scalability and Modularity**
- The initial prototype targets elbow actuation.
- Design is scalable to include shoulder actuation grounded to chest armor.
- The modular approach ensures meaningful demonstration even if full-body integration is not achieved.

**Criterion for Success**

The final solution will be a wearable exoskeleton capable of assisting the user in lifting and holding objects up to 10 kg through a dual-actuation BLDC–servo system with a detachable drivetrain for free arm movement, powered by an onboard 6S battery, lightweight (under 3 kg excluding the battery), and controlled via EMG signals or a manual override panel to ensure safe, efficient, and natural operation.

Instant Nitro Cold Brew Machine

Danis Heto, Mihir Vardhan

Instant Nitro Cold Brew Machine

Featured Project

# Instant Nitro Cold Brew Machine

Team Members:

- Mihir Vardhan (mihirv2)

- Danis Heto (dheto3)

# Problem

Cold brew is made by steeping coffee grounds in cold water for 12-18 hours. This low-temperature steeping extracts fewer bitter compounds than traditional hot brewing, leading to a more balanced and sweeter flavor. While cold brew can be prepared in big batches ahead of time and stored for consumption throughout the week, this would make it impossible for someone to choose the specific coffee beans they desire for that very morning. The proposed machine will be able to brew coffee in cold water in minutes by leveraging air pressure. The machine will also bring the fine-tuning and control of brewing parameters currently seen in hot brewing to cold brewing.

# Solution

The brew will take place in an airtight aluminum chamber with a removable lid. The user can drop a tea-bag like pouch of coffee grounds into the chamber along with cold water. By pulling a vacuum in this chamber, the boiling point of water will reach room temperature and allow the coffee extraction to happen at the same rate as hot brewing, but at room temperature. Next, instead of bringing the chamber pressure back to atmospheric with ambient air, nitrogen can be introduced from an attached tank, allowing the gas to dissolve in the coffee rapidly. The introduction of nitrogen will prevent the coffee from oxidizing, and allow it to remain fresh indefinitely. When the user is ready to dispense, the nitrogen pressure will be raised to 30 PSI and the instant nitro cold brew can now be poured from a spout at the bottom of the chamber.

The coffee bag prevents the coffee grounds from making it into the drink and allows the user to remove and replace it with a bag full of different grounds for the next round of brewing, just like a Keurig for hot coffee.

To keep this project feasible and achievable in one semester, the nitrogenation process is a reach goal that we will only implement if time allows. Since the vacuum and nitrogenation phases are independent, they can both take place through the same port in the brewing chamber. The only hardware change would be an extra solenoid control MOSFET on the PCB.

We have spoken to Gregg in the machine shop and he believes this vacuum chamber design is feasible.

# Solution Components

## Brewing Chamber

A roughly 160mm tall and 170mm wide aluminum chamber with 7mm thick walls. This chamber will contain the brew water and coffee grounds and will reach the user-set vacuum level and nitrogenation pressure if time allows. There will be a manually operated ball valve spout at the bottom of this chamber to dispense the cold brew once it is ready. The fittings for the vacuum hose and pressure sensor will be attached to the screw top lid of this chamber, allowing the chamber to be removed to add the water and coffee grounds. This also allows the chamber to be cleaned thoroughly.

## Temperature and Pressure Sensors

A pressure sensor will be threaded into the lid of the brewing chamber. Monitoring the readings from this pressure sensor will allow us to turn off the vacuum pump once the chamber reaches the user-set vacuum level. A temperature thermocouple will be attached to the side of the brewing chamber. The temperature measured will be displayed on the LCD display. This thermocouple will be attached using removable JST connectors so that the chamber can be removed entirely from the machine for cleaning.

## Vacuum Pump and Solenoid Valve

An oilless vacuum pump will be used to pull the vacuum in the brewing chamber. A solenoid valve will close off the connection to this vacuum pump once the user-set vacuum pressure is reached and the pump is turned off. To stay within the $100 budget for this project, we have been given a 2-Stage 50L/m Oil Free Lab Vacuum Pump on loan for this semester. The pump will connect to the chamber through standard PTFE tubing and push-fit connectors

If time allows and we are able to borrow a nitrogen tank, an additional solenoid and a PTFE Y-connector would allow the nitrogen tank to connect to the vacuum chamber through the same port as the vacuum pump.

## LCD Display and Rotary Encoder

The LCD display allows the user to interact with the temperature and pressure components of the brewing chamber. This display will be controlled using a rotary encoder with a push button. The menu style interface will allow you to control the vacuum level and brew time in the chamber, along with the nitrogenation pressure if time allows. The display will also monitor the temperature of the chamber and display it along with the time remaining and the current vacuum level.

# Criterion For Success

- A successful cold brew machine would be able to make cold brew coffee at or below room temperature in ten minutes at most.

- The machine must also allow the user to manually control the brew time and vacuum level as well as display the brew temperature.

- The machine must detect and report faults. If it is unable to reach the desired vacuum pressure or is inexplicably losing pressure, the machine must enter a safe ‘stop state’ and display a human readable error code.

- The reach goal for this project, not a criterion for success, would be the successful nitrogenation of the cold brew.

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