How to make your own robot

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Device Plus The editorial team

2016 year 5 month 23 Japan

How to use with Arduino The stepping motor of components and sensors is 2 Make your own robot on wheels ：

Once you know the basics of using stepper motors , You can create some interesting projects , You can even make your own robot . This time, , I will try to build a 2 Wheel robots .

On top In an article , Use Arduino Control motor - Use servo motor for steering Make a remote control car , We made a remote control car , Among them, ordinary motor provides forward / Backward movement , The servo motor controls the steering .

In this 2 Wheel robot , forward / Backward movement and rotation can be accomplished by two motors placed side by side . You often see this 2 Robot with wheelbase as motion source . I want to make something with this versatility .

Make your own robot with this electronic construction recipe

About time ：90 minute
Parts needed

• Arduino UNO R3
• 42mm Stepper motor 12V x2
• L6470 Stepper Motor Driver Kit
• L6470/42x34mm Stepping motor screw set （ Japanese version ）
• 5mm Universal mounting base （ A set of 2 individual ）
• 006P 9V Battery holder

Design of two wheeled robot

chart 1 – by 2 Wheel robot modeling

First , You need to think about 2 Complete design of wheeled robot . If there is 2 A motor , You can make one with a simple design 2 Wheel robots .2 A motor that rotates in the same direction provides forward / Move backward , Reverse rotation provides rotational capacity . This point , That is, basic motion control can be easily realized by using two motors , This has been adopted in many fields . Let's measure the dimensions of the stepping motor and other components to be used , And make a fuselage matching this size .

I use 3D The parts of the printer can be found here .

chart 1 Use free modeling software “123d design”, It shows that I'm right 2 The idea of a simple design of a wheeled robot body . I'm thinking about using a round piece of wood as a base , And set the stepping motor 、Arduino And battery connected to it . Because the two wheeled robot may eventually overturn forward or backward , So I will install a small ball caster on the back of the board as a support .

Determine the size of the wheel , Please place the stepping motor in the figure 1 On the round wooden block shown , Then measure the height from the floor . To that height , Add casters floating a little + 2-3mm The height at the time , You get the diameter of the wheel .

chart 1 3D Circular plates and wheels produced by printers

chart 2 Support ball casters

Besides , I simulated the part that locks the stepper motor to the board . There are four on the shaft side of the stepping motor 4mm Screw holes , So I made a part , They can be used to lock the circular plate to the stepper motor .

chart 2 The part that fixes the stepping motor on the circular plate

chart 3 3D Parts printed by printer

once 3D The printer produces parts , I installed the stepping motor and confirmed the size . It fits perfectly .

chart 4 – Parts assembly

Connect the driver to the stepper motor .

Because all components are installed on the 12 Cm board , So we need to use space as carefully as possible . Due to the stepper motor driver L6470 The position and size of the board and screw hole are the same as that of the surface of the stepping motor , I can screw the driver to the back of the stepping motor . By doing so , I can save a little space .

chart 5 – Temporarily remove the screws and install the drive board .

chart 6 – The drive plate on the back of the stepper motor

Use Arduino Circuit for driving two stepping motors

before , We only drive one stepper motor . This time, , We need to drive two stepper motors . Use a method called daisy chain ,L6470 It can control multiple stepping motors .

Chrysanthemum chain It's a kind of Wiring scheme , Among them, several devices are connected together in sequence or in a ring . In addition to the complete single circuit , A system that contains internal loops cannot be called a daisy chain .

And L6470 The circuits required to perform the daisy chain are as follows . Because there are many wires , Please be careful not to make mistakes when wiring .

chart 3 – Connect the circuit of two stepping motors

The difference from the circuit with only one time is , The first and second stepper motors now have a component that connects them . use L6470 After the data sheet is confirmed , The first stepper motor is connected to SDO, The second stepper motor is connected to SDI. Send and receive data through this part .

chart 4 – L6470 Sketch Map

Conclusion

After the circuit wiring is completed , I want to say it's time to start the programming part , However, the procedure for processing multiple stepping motors may be a little complicated , It may be wise to step back and learn more about stepper motor programming . If all goes well , The two stepper motors will be synchronized as in the following video .

How to make your own robot （ The first 2 part ）

Look at the original

Device Plus The editorial team

2016 year 5 month 24 Japan

How to be in 2 Make your own robot on wheels , Use a Arduino Stepper motors for components and sensors …… The first 2 part

In the 1 In the part , We Use the library to drive the stepping motor . This time, , We will study stepper motor programming in more detail and learn how to control it , Problems encountered when dealing with stepper motors , And some solutions .

Electronic building formula

About time ：90m
Parts needed

• Arduino UNO R3
• 42mm Stepper motor 12V x2
• L6470 Stepper Motor Driver Kit
• L6470/42x34mm Stepping motor screw set （ Japanese version ）
• 5mm Universal mounting base （ A set of 2 individual ）
• 006P 9V Battery holder

Stepper motor comments

chart 1 – Stepper motor and L6470

In this article, I will review how to control stepping motor by programming . It can be seen from the following characteristics , Compared with ordinary motor and servo motor , Stepper motor is unique in that it can control rotation .

• The motor ： Rotate when powered on
• Servo motor ： Corresponding to a signal in 0 To N Rotate within degrees
• Stepper motor ： It can be controlled without signal limitation

Besides , When you actually control the motor, you send PWM The signal . in other words , If you will Arduino Directly connected to the stepper motor , Control will be difficult . So usually , For things like Arduino Such a microcontroller , You will want to control the stepping motor through the motor driver , This makes various types of control possible .（ Information about handling common motor drives , see also #12.）

This time it was used L6470 Stepper motor driver is cheap and has on-board control / Oscillator circuit , Used to detect stepping motor 、DSP And communications I/F Over current . Basically , When you try to control the rotation or power of the motor or need precise movement , You need to choose a motor driver with the following functions and capabilities to complete your circuit .

[](http://www.rohm.com/web/global/search/parametric/-/search/Stepping Motor)

[ Stepper motor driver directory – ROHM](http://www.rohm.com/web/global/search/parametric/-/search/Stepping Motor)

Because I want a product that is easy to use and cheap , So what I use is L6470. however , Last and previous time , When I try to drive the stepper motor , I expect it to rotate . contrary , I only have noise and vibration , But the shaft doesn't rotate . I want to know if I have done anything to make it strange ？

Stepper motor “ Out of step ” The phenomenon

When using stepping motor , You often encounter out of step . In short , Out of step means that the actual motion of the stepping motor cannot keep up with the rotation control signal , The expected rotation position of the motor driver is out of alignment with the actual position of the stepping motor , As a result, synchronization is lost and the motor does not rotate .

There are many reasons for jumping out . Driving a stepper motor as described below usually causes it .

• Sudden acceleration or deceleration stepping motor
  • The timing of sudden acceleration and deceleration brings the possibility that the signal is not synchronized with the motor . In these cases , First, gradually accelerate / Slowing down will eliminate this possibility .
• Insufficient torque
  • If the motor does not have enough torque （ Rotating power ）, Out of step may occur . under these circumstances , You must switch to a motor with the required torque .
• The driving voltage is low / unstable
  • If the drive voltage is low / unstable , This may lead to out of step .L6470 Specifications 8V-45V, But in 8V Be careful when running under .
• The influence of vibration
  • If vibration is applied to the motor , It may lead to out of step .

Generally speaking , When out of step occurs , All the above reasons are possible , But sudden acceleration or overspeed caused by insufficient torque is the most common reason . therefore , If your stepping motor fails , These reasons are worth investigating .

In addition, Yifa semiconductor sells L6470 Of , There are detailed instructions , You can also refer to it .

L6470 Product description

Program the stepping motor

Now? , Let's delve into the theme of this article , Stepper motor programming . To pass through L6470 from Arduino Control stepping motor , You must be right about l6470 Program to send control signals . The circuit is as follows .

chart 1 – Connect Arduino、L6470 And stepping motor circuit

Stepper motor control program flow

The following is the step motor program . We will now read the flow of this program .

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#include <Arduino.h>#include <SPI.h> //(1) Import for SPI transmission //(2) Define the stepper motor pin#define PIN_SPI_MOSI 11#define PIN_SPI_MISO 12#define PIN_SPI_SCK 13#define PIN_SPI_SS 10 void setup(){ delay(1000); Serial.begin(9600); //(3) Initialize the stepper motor pin pinMode(PIN_SPI_MOSI, OUTPUT); pinMode(PIN_SPI_MISO, INPUT); pinMode(PIN_SPI_SCK, OUTPUT); pinMode(PIN_SPI_SS, OUTPUT); digitalWrite(PIN_SPI_SS, HIGH); //(4) SPI signal to commence SPI transmission SPI.begin(); SPI.setDataMode(SPI_MODE3);// When SCK is high, send/receive data, when idle, set pin to HIGH SPI.setBitOrder(MSBFIRST);// Transmission from MSB //(5) L6470 settings L6470_setup();} //**********************************************//(6) SPI transmission method//void L6470_send(unsigned char value){ digitalWrite(PIN_SPI_SS, LOW); SPI.transfer(value); // Send control signal via SPI transmission digitalWrite(PIN_SPI_SS, HIGH); } //// (7) L6470 setup//void L6470_setup(){ // Device settings L6470_send(0x00); L6470_send(0x00); L6470_send(0x00); L6470_send(0x00); L6470_send(0xc0); //Set maximum revolution speed L6470_send(0x07);//register address L6470_send(0x20);//value(10bit),default 0x41 //Voltage setting when motor is idle L6470_send(0x09);//register address L6470_send(0xFF);//value(8bit),default 0x29 //Voltage setting when motor rotating at constant speed L6470_send(0x0a);//register address L6470_send(0xFF);//value(8bit),default 0x29 //Voltage setting when accelerating L6470_send(0x0b);//register address L6470_send(0xFF);//value(8bit),default 0x29 //Voltage setting when decelerating L6470_send(0x0c);//register address L6470_send(0xFF);//value(8bit),default 0x29 //full step, half step,1/4,1/8,…,1/128 step setting L6470_send(0x16);//register address L6470_send(0x00);//value(8bit} //// (8)Main process - loop()//**********************************************void loop(){ //360 degrees - Turn one complete revolution L6470_send(0x50);// Run(DIR,SPD),0x51:Forward,0x50:Reverse L6470_send(0x00); L6470_send(0x20);// Rotation speed settings L6470_send(0x00); delay(1604);// Turn 1 time every 1604ms L6470_send(0xB8);// Hard stop}

Control signals —— About SPI transmission

First ,L6470 and Arduino The control signals between are exchanged by calling SPI transmission （ Serial peripheral interface ） Method . such SPI Transmission is used in Arduinos and IC Chips and other microcontrollers exchange signals .

On the second line of the program （1） Of “#include SPI.h” Expression , I'm going to Arduino Upper use SPI transmission . When using the library , Please remember these “#include <***.h>” Expressions always exist .

Next , stay （2） in , I set up L6470 Pins used . ad locum , You can see the written MOSI and MISO. These are SPI The basic signal line used for transmission .

stay SPI In transit , The signal line consists of 3 There are four basic elements （ Use SS When the signal is 4 Elements ）. Each signal line has a specific clock （SCK）、 The output signal （MOSI：Master Out Slave In） And input signals （MISO：Master In Slave Out）. During actual transmission , The communication arrangement is Arduino Output standard clock signal (SCK), Then with L6470 Use it together In and Out（MISO and MOSI） The connection transmits data back and forth .

• SCK—— The serial clock
• MISO – Main in and out
• MOSI – The main out comes from the in
• SS – Slave selection

stay (3) in , Set the pin mode of the signal line used . Next , stay (4) in , Set the... To use SPI transmission mode . The device being connected determines the mode .

once SPI Transmission preparation is complete , stay (5) in , We can finally use SPI Transfer and start L6470 Set up . Actually send SPI The part that transmits the signal is (6) L6470_send() How to write a function .

It's going on L6470 When setting , Please set the required elements according to the specifications recorded in the data sheet and manual .

L6470 Data sheet

When you view the contents of the data table , You will see the following command address table . This time because we use 12026 The motor , So pass SPI The transfer sends the register address recorded in the table to initialization L6470.

As an example of how to use tables in programming ：

123	//Highest revolution speed settingL6470_send(0x07);//register addressL6470_send(0x20);//value(10bit),default0x41

The above is the code . If we were “ Maximum speed ” View in the table of function row , The address is “0x07”, The length is “10” position , The initial value is “0x20”（ With 12026 Model as an example ）. adopt SPI Transmit the values in the transmission table , You can make various settings .

surface 1 L6470 Data sheet .

Once the initialization is complete , stay (8) Find the actual command to drive the stepping motor in the main process . You can see the various commands recorded in the data table again .

• Rotation command
  0x51（ Positive rotation ）、0x50（ reverse ）
• stop it （ soft ） command 0xB0

In this example , Send forward or reverse rotation command , And then there was 20 Bit rotation speed command , Then there is the delay （1604）. This makes it rotate during this time . If you change this speed value , It can accelerate or decelerate .

This is the use of Arduino adopt L6470 The process of driving the stepping motor . in addition , Corresponding to this , By changing some connection methods , It can control multiple stepping motors as introduced last time .

Let's try driving a two wheeled robot

Now we know the programming function flow of stepping motor , Let's finish 2 Wheel robots . I used in my last article 3D The printer completes the printing of wheels and body , The necessary components will now be installed on the body , So you can make your own robot completely .

chart 2 – All the parts needed to make your own robot are installed on your body

Installed Arduino、 Bread board and for stepping motor （2 Series ） Of 9V After battery , There is little room left …… Oh dear .
therefore , I didn't use it Arduino UNO, Instead, try to replace it with Arduino Pro Mini.

chart 3 – Use Arduino Pro Mini, Perfect ！

chart 4 – It is installed neatly on the bread board

chart 5 – The wheel is firmly mounted on the shaft , So it won't slip

After installing all components , We can finally turn on the power and try to drive it .

Useful ！ In the video , A step motor is connected 12V Adapter . When I connect 9V Battery time , They are a little too heavy , I noticed that the stepping motor didn't have enough torque . under these circumstances , If it's too heavy , As I described before , You can replace the motor itself , Reduce weight , Or further improve the power supply to make stable operation possible .

Conclusion

This time, , We use stepping motor to make your own robot on two wheels . Movement occurs in code . When you make your own robot , You can add other things , For example, install light sensors on each side , Make a robot that moves towards the brightest light , Or a robot moving towards sound , Even a robot that can be driven by a smart phone passes through the previously introduced ESP- WROOM -02 Use WIFI signal communication . Various applications are possible . I may try to introduce some improvements in subsequent Posts .

The next time , I think I'll make a device that uses magnetic sensors or other cool things .