# Title Team Members TA Documents Sponsor
36 Anti-Lock Braking for Bicycles
Aidan Rodgers
Ethan Chastain
Leon Ku
Nithin Balaji Shanthini Praveena Purushothaman design_document4.pdf
Anti-Lock Braking for Bicycles

Team Members:
- Ethan Chastain (ecc5)
- Aidan Rodgers (aidanfr2)
- Leon Ku (leonku2)

# Problem

Bicycles present a challenge because they often lack or charge a premium for the features that cars have, like Anti-Lock Braking Systems (ABS). This happens because bicycles are primarily designed for short distance commuting. Unlike cars that come with a range of amenities, bicycles prioritize simplicity. However, this difference in design leads to a discrepancy in safety and convenience features. Bicycle riders do not have the braking capabilities and automated speed regulation that many cars offer. This absence of features like ABS can be particularly dangerous as bicycles are prone to skidding; thus increasing the risk of accidents. As mobility solutions, bicycles sacrifice these functionalities, which means riders must navigate roads with heightened awareness and limited technological assistance.

# Solution

In order to improve the safety of bicycles via cheaper, preventative features, we could consider adding technologies commonly used in cars. For instance, adding an Anti-lock Braking System (ABS) would reduce the risk of skidding by braking more efficiently; thereby improving overall safety. More importantly, the use of ABS ensures better stability for riders and helps prevent accidents like collisions at an intersection. By embracing these technologies, bicycles can offer riders safer, cheaper rides with improved ease of use. We plan to use one of the bikes provided by the workshop and add a braking system that both detects locking and modulates braking to account for it.

# Solution Components

## Subsystem 1 - Speed sensing

We plan to use a Hall effect sensor (potential part number: DRV5023BIQLPGMQ1) to sense rotational motion of the bicycle’s rear wheel, to determine the speed of the bicycle. This will interface directly with the microcontroller to allow for the braking system to pulse the brakes if locking occurs. The sensor will also be used to record data, in order to test for proper operation.

## Subsystem 2 - Braking

This system takes inputs from the microprocessor to operate the brakes of the bicycle. The braking subsystem consists of a servo motor and a gear system to mechanically pull the brake cable, upon input from the microprocessor. As this system will interfere with the normal mechanical braking system of the bicycle, we will implement buttons in place of the typical brake controls on the handlebars, which will interface with the microprocessor to allow for the bicycle to brake.

## Subsystem 3 - Microprocessor

The microprocessor subsystem will take information from the Hall effect sensors about the rotational speed of the bicycle’s wheel. This subsystem will use an ATMega controller to implement the control algorithms. We plan to use LQR or PID control as a means of tracking constant slopes to prevent wheel locking when decelerating. By this method, we will be able to flash a controller onto the microcontroller in order to embed our control on the PCB.

# Criterion For Success

To qualitatively test the bicycle’s anti-lock braking mechanism, we will place the bicycle on a treadmill and slam the brakes, to observe visually the bicycle’s braking operation. During this test, data from the Hall effect sensor relating to the speed of the bicycle’s rear wheel will be recorded during the test, demonstrating that the bicycle is slowing down properly and efficiently.

Control System and User Interface for Hydraulic Bike

Iain Brearton

Featured Project

Parker-Hannifin, a fluid power systems company, hosts an annual competition for the design of a chainless bicycle. A MechSE senior design team of mechanical engineers have created a hydraulic circuit with electromechanical valves, but need a control system, user interface, and electrical power for their system. The user would be able to choose between several operating modes (fluid paths), listed at the end.

My solution to this problem is a custom-designed control system and user interface. Based on sensor feedback and user inputs, the system would change operating modes (fluid paths). Additionally, the system could be improved to suggest the best operating mode by implementing a PI or PID controller. The system would not change modes without user interaction due to safety - previous years' bicycles have gone faster than 20mph.

Previous approaches to this problem have usually not included an electrical engineer. As a result, several teams have historically used commercially-available systems such as Parker's IQAN system (link below) or discrete logic due to a lack of technical knowledge (link below). Apart from these two examples, very little public documentation exists on the electrical control systems used by previous competitors, but I believe that designing a control system and user interface from scratch will be a unique and new approach to controlling the hydraulic system.

I am aiming for a 1-person team as there are 6 MechSE counterparts. I emailed Professor Carney on 10/3/14 and he thought the general concept was acceptable.

Operating modes, simplified:

Direct drive (rider's pedaling power goes directly to hydraulic motor)

Coasting (no power input, motor input and output "shorted")

Charge accumulators (store energy in expanding rubber balloons)

Discharge accumulators (use stored energy to supply power to motor)

Regenerative braking (use motor energy to charge accumulators)

Download Competition Specs:

Team using IQAN system (top right corner):

Team using discrete logic (page 19):