Getting Started

1 Usage methods and safety precautions of AA batteries

1.1 The AA batteries supported by Maqueen Plus V3

If you purchase the AA battery version of Maqueen Plus, it supports two specifications: 1.5V AA batteries and 1.2V nickel-metal hydride rechargeable AA batteries. When purchasing batteries, please be careful not to buy AAA batteries. AA batteries can be purchased in most supermarkets. It should be noted that 1.5V alkaline batteries are disposable batteries and cannot be charged. Otherwise, explosion or fire may occur.

1.2 Rechargeable nickel-metal hydride batteries

The nickel-metal hydride rechargeable battery is a type of rechargeable battery that is safer than lithium batteries and less prone to explosion and fire, with a voltage of 1.2V per cell. The size of the nickel-metal hydride battery is the same as that of the AA alkaline battery. Considering the danger that users might mistakenly charge alkaline batteries, Maqueen Plus has not designed an on-board charging circuit. Therefore, if you need to use nickel-metal hydride batteries, you need to purchase a nickel-metal hydride rechargeable battery and charger set.

Note: No matter what type of AA battery is used, when installing, it is necessary to pay attention to the positive and negative electrodes of the battery corresponding to those on the battery box and must not be installed reversely.

6. Usage methods and safety precautions of 18650 lithium batteries

2 Function description

1. The rechargeable battery version of Maqueen Plus V3 is powered by a 3.7V 18650 rechargeable lithium battery. Do not use other types of batteries.

2. Supports pointed-tip batteries (67mm) and batteries with protection boards. Does not support flat-head batteries (65mm. The size of flat-head batteries is too short and may result in poor contact). As shown in the picture:

   

3. Maqueen Plus has its own charging function and uses the TYPE-C or MicroUSB interface to charge the battery.

4. Please use a charging head with guaranteed quality, a voltage of 5V, and a current of 2A or more to charge the battery. Currently, most mobile phone chargers can charge the lithium battery. When charging, the outer ring of the battery indicator light will show red. When fully charged, it will show green. As shown in the picture:

   

5. Do not insert the MicroUSB and TYPE-C interfaces for charging simultaneously. Although Maqueen Plus has relevant protection inside, this is an operation that is not allowed.

6. The charging time is about 4 hours to be fully charged.

2.2 Safety precautions of 18650 lithium batteries

The 18650 battery is a type of high-capacity battery and needs to be used in the correct way; otherwise, safety accidents such as overheating, explosion, and fire may occur.

2 .2.1 Battery storage

1. Batteries should be stored in a cool and dry environment.
2. Batteries cannot be placed in areas with water, let alone soaked in water. Water is a conductor and can cause short circuits and overheating of the battery.
3. Batteries cannot be stored in high-temperature or high-humidity environments, as it will intensify the battery's reaction, resulting in reduced lifespan or capacity.
4. Batteries cannot be placed together with conductive objects such as metals, as it can easily cause short circuits of the battery.
5. The insulating tape of the battery should not be damaged, as it can easily cause short circuits of the battery.
6. If the 18650 battery is not used for a long time, it should be removed from the device and stored in an insulating box. For devices where it is not convenient to remove the battery, the main power switch of the device should be turned off to avoid improper placement causing short circuits of the battery.
7. Batteries should be stored in places that are not easily accessible to children to avoid safety accidents.
8. People under the age of 14 should use 18650 batteries under the guidance and supervision of adults.

2.2.2 Safety matters regarding battery usage

1. During the use of Maqueen Plus, it is not allowed to touch the circuit board and battery parts with any conductive objects, such as tweezers, pliers, screwdrivers, etc., to avoid short circuits that damage the equipment or cause danger.

2. After use, the "POWER SWITCH" on the battery board needs to be turned off in time. Long-term power-on may cause equipment damage, battery over-discharge, and even short circuits that cause fires and other dangers.

3. When using the 18650 battery, the positive and negative electrodes need to be distinguished. Incorrect installation may lead to equipment damage, fire, explosion and other dangers.

Important safety tip: The entire cylinder of the 18650 battery is the negative electrode. On the cylindrical surface of the 18650 battery, there is a layer of insulating tape wrapped. Do not damage the tape. If the tape is damaged, the negative electrode metal surface will be exposed. When the metal surface of the cylinder touches the positive electrode with a metal object, the battery will short circuit. Do not attempt to short-circuit any negative electrode position and positive electrode position with metal items such as screwdrivers and tweezers! Any battery short circuit can cause dangers such as overheating, fire and even explosion!

2.2.3 Safety matters regarding battery installation

1. Pay attention to the 18650 battery board on Maqueen Plus. The positive and negative electrodes are marked in multiple places on the battery board. See the picture below:

   

2. Before installing the battery, please note that the power switch labeled "POWER SWITCH" needs to be switched to the "OFF" side to turn off the power of Maqueen Plus. As shown in the picture:

   

3. When installing the battery, the "+" mark of the battery faces the "+" mark direction of the battery board, and the "-" faces the "-" mark direction. And put the battery pull strap on the battery. As shown in the picture below.

   

The 18650 battery needs to be installed by the teacher or under the guidance of the teacher. Do not allow children or students to install the 18650 battery by themselves to avoid danger.

2.2.4 Safety matters regarding battery disassembly

When you need to disassemble the 18650 battery from Maqueen Plus, please be sure to pay attention to the following points:

1. Do not directly pull out the battery with your fingers. To ensure reliable contact of the battery, the 18650 battery box is installed very tightly. If you directly pull it out with your fingers, it is easy to cause serious damage to your fingernails.

   

2. Do not pry the battery with any sharp objects such as a screwdriver. It is easy to cause a short circuit and explosion of the battery and hurt your eyes and body.

   

3. To remove the battery, a "battery pull strap" is required. Gently pull the battery out of the battery compartment.

   

3. POWER SWITCH

1. For the safety of use, Maqueen Plus is equipped with two power switches. They are respectively located on the battery board and the bottom plate of the car. It can operate normally only after both switches are turned on. As shown in the picture:

4 Installation methods of the battery board and the metal bracket

Maqueen Plus V3 in order to give students a certain assembly experience, the battery board and the metal bracket were not installed during production.

The specific installation methods are as follows:

4.1 Tool Preparation

• Screwdriver *1
• 35mm copper column *5
• Metal adjustment bracket *1
• Installation screw *5
• Sensor installation bracket *1
• Hand-twisted screw *4
• Battery board *1
• Power connection line *1
• Laser ranging sensor *1

4.2 Install the battery board

1. Install the 35mm supporting copper columns, which need to be screwed in place to ensure the flatness of the battery board after installation. Due to the differences in the thread manufacturing process, some copper columns may not be easily screwed in place. At this time, please use pliers to assist in the installation appropriately. But do not install it violently to avoid damaging the thread. The installation position is as shown in the picture:

   

2. Use screws to install the battery board on the copper columns, as shown in the picture:

   

3. Install the connection line, as shown in the picture:

   

4.3 Install the metal bracket and the laser ranging sensor

1. Install two 35mm copper columns at the position as shown in the picture:

   

2. Use hand-twisted screws to install the adjustment bracket on the battery board. Please note that the front and rear directions of the bracket in the picture should not be installed wrongly, otherwise it will block the USB interface of the micro:bit, as shown in the picture:

   

3. Use hand-twisted screws to install the sensor fixing bracket, as shown in the picture:

   

4. Install the sensor, as shown in the picture:

   

4.4 The form after installation is completed

5. Motor replacement method

Maqueen Plus V3 adopts a design with replaceable motors. If the motors are damaged due to high-intensity use or being dropped, they can be replaced in the following way.

5.1 Remove the motor

1. Turn off the power of Maqueen Plus V3.

2. Pull out the two wheels.

3. Pull out the connection lines on the motor. As shown in the picture:

   

4. Use a screwdriver to unscrew the 4 motor screws at the bottom. As shown in the picture:

   

The motor disassembly is completed.

5.2 Install the motor

1. Install the buckle on the motor, as shown in the picture:

   

2. Install the motor on the base plate, as shown in the picture:

   

3. Install the connection line. This position is not very easy to install and requires some patience, as shown in the picture:

   

4. Install the wheels. When installing the wheels, pay attention to align the plane of the motor shaft with the plane of the wheels to avoid failure to install or damage to the wheel shaft hole. As shown in the picture:

   

6. Calibration method of the line-tracking sensor

The line-tracking sensor has been calibrated before leaving the factory. Usually, you don't need to calibrate it. If it is found that the line-tracking sensor cannot correctly recognize the black line, you can try to calibrate the line-tracking. The method is as follows:

1. Place the 5 probes of the line-tracking sensor on the black area at the same time. (Make sure that all 5 probes are in the black area)
2. Turn on the power of Maqueen Plus.
3. Press and hold the "Calc-Key" button for about 2 seconds. The line-tracking indicator light starts to flash, and then release the button. The calibration is completed.
4. Check the calibration result: Put the line-tracking sensor on the white background, the line-tracking indicator light goes out. Put it on the black background, the line-tracking indicator light is on. The calibration is correct.

The line-tracking sensor uses the grayscale detection method to recognize the black line. Therefore, not all black lines can be effectively recognized. For materials that cannot be recognized, even if calibrated, they cannot be correctly recognized. For example, laser-printed maps may not be recognized.

7. Example tutorial based on MakeCode programming

7.1 Open the MakeCode platform and load the library

Click the link to enter the MakeCode graphical programming platform: https://makecode.micro:bit.org/

Click "New Project" to create a new project, as shown in the picture:

In the pop-up dialog box, give a name to the project and then click "Create", as shown in the picture:

Load the Maqueen Plus library:

Click the "Settings icon" and then click "Extensions", as shown in the picture:

Load the Maqueen Plus library: Search for dfrrobot in Extensions, and then select

"DFRobot_MaqueenPlus_V2", as shown in the following picture:

Note: Maqueen Plus V3 and Maqueen Plus V2 use the same library. To ensure that the link does not change, the name of the library is still V2, but all the functions of V3 have been integrated.

The loading of the library is completed. The loaded library is shown in the picture. It will contain the libraries of both the infrared and the matrix laser ranging sensors at the same time.

Safety Precautions

Since Maqueen Plus is a STEM education product and is presented in a bare - board form, the following safety precautions should be noted during use:

1. The use of batteries must strictly comply with the battery usage methods and safety precautions. Otherwise, it may damage the product and cause risks such as overheating and combustion.
2. Do not touch the product, especially the circuit board part and the battery part, with sharp objects like screwdrivers. This is to avoid damaging components or causing danger.
3. Do not touch the product's circuit board with metal objects to prevent short - circuits, which can damage the product and lead to risks such as overheating and combustion.
4. The product is not waterproof and should not come into contact with liquid substances such as water and beverages. If liquid is accidentally spilled on the product, immediately turn off the power and remove the battery. Only attempt to power it on after the moisture has completely dried.
5. When storing the product, do not stack multiple products together to avoid component damage, and even the risk of power short - circuits, which may cause fires and personal injury.