In the previous three sections we focused on developing the TalTech Iseauto, it is now time to take a look at what the final version of Iseauto currently looks like, which sensors are included in the bus, and what is it capable of.

Let’s start with the look of the bus, which is designed by Silberauto AS designer Sven Sellik. Iseauto is designed to be symmetrical, which makes it difficult to detect the rear and the front end of the bus by simply looking at it from the outside. The main color is dark gray, in addition, black and white colors are used. The height of the bus is 2.4 m, the length is 3.5 m and the width is 1.5 m and it weighs 1.1 tons. The following pictures give you some idea what a bus looks like.

The back of Iseauto[/caption]

Next, let’s look at where and how different sensors are located on the bus. First of all, the lidars, because their importance on the bus is difficult to overemphasize. We use Volodyne’s 3D lidars that create 360-degree 3D images of objects around the bus. They can be used for local positioning and object detection. Initially, it was planned to place one lidar on the roof at the front of the bus, and the other on the roof at the back of bus. But during the development, the results were achieved by placing two lidars in the front corners of the roof at a small angle (with an angle to the ground) and, in addition, one lidar was placed in the front of car a couple of hundred centimeters above the ground.

In addition to local positioning, the bus is able to position itself globally. For this purpose, the RTK-GNSS (Real Time Kinematic Global Navigation Satellite System) is placed on the bus, which is accurate to a few centimeters. Its main components are the GPS module and two antennas, one of which is positioned in front of the bus and the other at the rear. The use of two antennas gives you the opportunity to get the moving direction very quickly. The module itself was originally positioned at the back of bus above the engine, but because the model of RTK-GNSS used on Iseautol also has an IMU (inertial measurement unit), it needs to be repositioned because the high current moving in the engine produces a magnetic field, resulting in a magnetometer located in the IMU giving incorrect results. The IMU sensor includes three sensors – an accelerometer, a gyroscope and a magnetometer, or a compass, which in co-operation can output the bus trajectory. The picture below shows the antenna at the front of the bus.

The next important sensors are cameras. There is 5 cameras currently on the bus. Two cameras are looking to front of the bus – one on top and one on the bottom of the car. One camera looks behind the bus and two cameras to the sides (located in the front of the bus on the sides). The cameras can easily detect objects. Currently, Iseauto only identifies people and cars, but in the near future, for example, traffic signs and animals detection will also be added.

There are also 8 ultrasound sensors installed into the bus, which are designed to identify objects in the vicinity of the bus to a few meters. Four sensors were placed in front and four in back of the bus.

Now as we have described all of the senosors installed onto Iseauto, let’s look at what it can do.

Today’s main feature of Iseauto is that it can follow a given trajectory at a predetermined speed on a pre-mapped area. With the cameras, Iseauto can also identify people and vehicles in the area. The maximum permitted speed on the bus is 20 km / h. As of today, his main disadvantage is that it can’t identify objects on the trajectory lane and therefore, he also has no ability to cross over these objects, if necessary. However, these functionalities are in development. To ensure safety, there must be at least one operator during the bus ride to stop the bus from emergency brake button, if necessary. Emergency brake system was described in the previous section.

And finally, what’s the future of Iseauto? On November 14, 2018, two months after the first public demo, Jaak Aaviksoo, the TalTech Rector, and Väino Kaldoja, Chairman of the Silberauto AS Group, signed the agreement that will provide the basis for the continued development of Iseauto and the creation of a new Iseauto. The goal is to create an Iseauto2 that externally looks the same, but which would be both mechanically and technologically substantially optimized and designed to drive on the public streets. Its development should be completed by the summer of 2019. The first Iseauto, however, remains the development and training platform for TalTech students, and will be also the testbench for artificial intelligence and sensory testing for Iseauto2.

The Ministry of Education and Research and Estonian Research Council are supporting the completion of the blog.

1. To develop a new product or service, in which it is desired to cooperate with TTÜ. During the cooperation project, it’s possible to connect your device to the LoRa WAN network and test the whole solution without additional costs. Certainly TTÜ already has experience in setting up, tuning and testing the connection. Among other things we can help you with the following LoRa WAN network related topics:
   1. Adding new equipments to the network and managing it
   2. Decrypting of encrypted packets for data processing
   3. Download data with the API for further processing and analysis
2. If you want to start offering your product or service for commercial purposes, the fastest way is to contact with Levira, who manages a specific LoRa WAN network and provides you with all the necessary guidance;
3. If you are a student and would like to learn how to use LoRaWAN or participating in some projects that needs low power wireless data transmission then contact us and we will help you out.

Advantages of LoRaWAN

• Very wide coverage range about 3-5 km in urban areas and 15 km in suburban areas
• Consumes very low power and hence battery will last for longer duration (up to 10 years)
• Uses Adaptive Data Rate technique to vary output data rate/Rf output of end devices. This helps in maximizing battery life as well as overall capacity of the LoRaWAN network. The data rate can be varied from 0.3 kbps to 27 Kbps for 125 KHz bandwidth.
• Uses 868 MHz/ 915 MHz ISM bands which is available world wide

Disadvantages of LoRaWAN

• Can be used for applications requiring low data rate i.e. upto about 27 Kbps.
• LoRaWAN network size is limited based on parameter called as duty cycle. It is defined as percentage of time during which the channel can be occupied. This parameter arises from the regulation as key limiting factor for traffic served in the LoRaWAN network.
• It is not ideal candidate to be used for real time applications requiring lower latency and bounded jitter requirements.

Introduction to LoRaWAN

LoRaWAN is radio network procotol designed to allow low-powered devices to communicate with Internet-connected applications over long range wireless connections. LoRaWAN operates in unlicensed radio spectrum. In Europe, LoRaWAN operates in the 863-870 MHz frequency band. This frequency band is divided into channels and most channels used by LoRaWAN have a duty-cycle as low as 1% or even 0.1%. The data rate depends on the used bandwidth and spreading factor. LoRaWAN can use channels with a bandwidth of either 125 kHz, 250 kHz or 500 kHz, depending on the region or the frequency plan.

The LoRaWAN specification defines three device types. All LoRaWAN devices must implement Class A, whereas Class B and Class C are extensions to the specification of Class A device:

• Class A devices support bi-directional communication between a device and a gateway. Uplink messages (from the device to the server) can be sent at any time (randomly). The device then opens two receive windows at specified times (1s and 2s) after an uplink transmission. If the server does not respond in either of these receive windows (situation 1 in the figure), the next opportunity will be after the next uplink transmission from the device. The server can respond either in the first receive window, or in the second receive window, but should not use both windows.
• Class B devices extend Class A by adding scheduled receive windows for downlink messages from the server. Using time-synchronized beacons transmitted by the gateway, the devices periodically open receive windows.
• Class C devices extend Class A by keeping the receive windows open unless they are transmitting, as shown in the figure below. This allows for low-latency communication but is many times more energy consuming than Class A devices.

Devices and applications have a 64 bit unique identifier (DevEUI and AppEUI). When a device joins the network, it receives a dynamic 32-bit address.

LoRaWAN 1.0 knows three distinct 128-bit AES security keys.

• The application key is only known by the device and by the application.
• When a device joins the network (this is called a join or activation), an application session key and a network session key are generated.
• The is shared with the network, while the is kept private. These session keys will be used for the duration of the session.

More information is on www.thethingsnetwork.com. Above information is partly based on the mentioned web site.