# Title Team Members TA Documents Sponsor
24 Grounded Rope Management System for Belaying
Abhyan Jaikishen
Chris Zhang
Daniel Hsu
Jason Paximadas design_document1.pdf
# Team members:
Abhyan Jaikishen (abhyanj2)

Chris Zhang (czzhang3)

Daniel Hsu (sehsu2)

# Problem:
When top-rope climbing outdoors or indoors, a climber requires a second person to belay to prevent large falls and minimize injuries. The belayer is responsible for maintaining slack and tension in a rope that is anchored at the top of the climb. As the climber moves up, the belayer reduces the slack of the rope to ensure that if the climber were to fall, the rope would catch them before dropping a dangerous amount. However, it is not always feasible to have a partner to belay you, especially for more spontaneous or frequent climbing.

# Solution:
We propose a ground-based rope management device. There exist auto-belays on the market, but these are very expensive, as well as usually anchored at the top of the wall, which makes them impractical for most outdoor and spontaneous usage. Our system would utilize a grigri (belayer rope management tool), combined with motors and sensors that are able to keep tension on the rope as the climber ascends, and lower the climber when they want to come down.

# Solution Components

- Motors: electric motors to act as the 2 “hands” of the belaying mechanism. These motors do not need to be strong enough to pull an entire human, since they only need to manage the rope, not anchor the climber.
- Servo for descent control: Small, low power servo will be needed to release level on grigri for descent.
- Tension/Force Sensors: Sensors will be needed to detect the amount of tension the rope is facing. Two possible ways to do this, either measure the resistance the motor encounters when taking too much slack away, or utilize tension sensors (something like a YZC-516C sensor)
- Wireless module: For the climber to be able to communicate with the belay system (tell it to lower/hold) remotely through remote control or app. Something like: CC2541 Bluetooth Wireless Module EBYTE RF Module

# Subsystem 1: Power
Will utilize standard wall outlets for power and take the necessary steps to supply motors, pcb, and other components with the correct amount. If time permits, utilizing a battery would be beneficial for outdoor use cases.

# Subsystem 2: Physical Grigri Control
Aforementioned motors will act as belay and guide hands to feed rope through grigri on both ends. A structure containing motor mounts and rope bends for the tension sensors will need to be created to house the main structure. This subsystem will be operated by subsystem 3.

# Subsystem 3: Processor and Communication
Mounted near or on the motor structure, we will house a PCB and other relevant components/controllers to read and analyze incoming data from motors and sensors. This is also where our wireless module will be contained. This subsystem will be responsible for collecting, processing, and transmitting relevant data for proper control of the grigri.

# Subsystem 4: Remote Control
Using the wireless module we decide on, a remote control will be used to determine the lowering and stopping of the rope. This subsystem may be physical, or simply utilize the data sent by the wireless module and process it via an App.

# Criterion for Success
System can detect and manage the slack in the rope properly as climber climbs
System can hold or lower climber while on wall
System can safely support climber’s fall
User can control belay remotely using remote control (or app TBD)

# Safety concerns
We intend to take full precautions against any dangers when testing and demoing the system.
We will have someone attached with a grigri behind the belay system. This way, in the event our project fails, the 2nd manually operated grigri will be able to catch the falls safely. Climbers often use this technique (a 2nd belayer), when first learning how to belay.

To eliminate all safety concerns, we will never climb above a height from which a freefall would be dangerous. Moreover, we intend to take advantage of the mats provided at all rock climbing facilities (crashpads), to ensure that even the small drops will pose no risk.

# Relevant links:
Grigri operation:
Double grigri system for testing:

Active Cell Balancing for Solar Vehicle Battery Pack

Tara D'Souza, John Han, Rohan Kamatar

Featured Project

# Problem

Illini Solar Car (ISC) utilizes lithium ion battery packs with 28 series modules of 15 parallel cells each. In order to ensure safe operation, each battery cell must remain in its safe voltage operating range (2.5 - 4.2 V). Currently, all modules charge and discharge simultaneously. If any single module reaches 4.2V while charging, or 2.5V while discharging, the car must stop charging or discharging, respectively. During normal use, it is natural for the modules to become unbalanced. As the pack grows more unbalanced, the capacity of the entire battery pack decreases as it can only charge and discharge to the range of the lowest capacity module. An actively balanced battery box would ensure that we utilize all possible charge during the race, up to 5% more charge based on previous calculations.

# Solution Overview

We will implement active balancing which will redistribute charge in order to fully utilize the capacity of every module. This system will be verified within a test battery box so that it can be incorporated into future solar vehicles.

Solution Components:

- Test Battery Box (Hardware): The test battery box provides an interface to test new battery management circuitry and active balancing.

- Battery Sensors (Hardware): The current battery sensors for ISC do not include hardware necessary for active balancing. The revised PCB will include the active balancing components proposed below while also including voltage and temperature sensing for each cell.

- Active Balancing Circuit (Hardware): The active balancing circuit includes a switching regulator IC, transformers, and the cell voltage monitors.

- BMS Test firmware (Software): The Battery Management System requires new firmware to control and test active balancing.

# Criterion for Success

- Charge can be redistributed from one module to another during discharge and charge, to be demonstrated by collected data of cell voltages over time.

- BMS can control balancing.

- The battery pack should always be kept within safe operating conditions.

- Test battery box provides a safe and usable platform for future tests.