Public Bicycles Evolving from Kiosk-Based to Dockless Systems
Electronic lock devices, Bluetooth, GPS, 3G/4G system independent standing-type transitioning

Public bicycles have begun appearing in major cities over the past few years. Anyone can rent a bicycle from a docking station installed throughout the city and return it, with payment available via credit card or mobile phone.

In London, bicycle users rent and return bicycles at docking station kiosks at designated locations as shown in Figure 1. While this method works well for bicycle tourists, it is inconvenient for commuters who do not have a nearby docking station. If a system were established where bicycles could be rented and returned anywhere, it would be efficient and convenient for commuters.

Recently, public bicycles in major cities in China are evolving from kiosk-based systems to dockless systems. Anyone can locate and rent a bicycle using a smartphone app. Bicycles are equipped with electronic lock devices and 3G/4G wireless networks, allowing them to be returned anywhere after use.

To use shared bicycles without docking stations, it is necessary to track bicycles on the network, unlock the locking device, and transmit user data. Independent standing-type bicycles equipped with battery-powered electronic lock devices and Bluetooth, GPS, and 3G/4G systems do not require docking stations because they can be safely parked throughout the city using electronic lock devices. Users locate the bicycle using a map on the smartphone app, then scan the bicycle's QR code to unlock the lock device. Upon arriving at the destination, users operate the bicycle's electronic lock device again using the smartphone app.

Since electronic lock devices are battery-powered applications, it is important to maintain the battery in a charged state at all times. These types of public bicycles require an easy method to charge the battery independently when there is no docking station. One method is to install solar panels on the bicycle. However, since this also depends on solar energy, energy production can be affected if the sun is not at an optimal angle. MPPT (maximum power point tracker) calculation optimizes the charging current between the solar panel and bicycle battery charger. (See Figure 3)

The bq25895 allows finding the MPPT point easily with simple calculations by measuring open-circuit input voltage and charging current through I2C configuration and integrated ADC. The bq25895 can not only charge the battery but can also be applied to solar panels on public bicycles to provide fully charged bicycles when commuters need them most.