Preface

First of all, let me introduce myself. At present, the author is engaged in work with many mechanical equipment, and these equipment rely on servo, cylinder, etc. for movement. However, these devices are all foreign, even if there are domestic devices, they are also very unstable, and the accuracy is not enough. Personally, I feel that the domestic automation equipment is not developed enough. It is hard to avoid thinking of basic education. Arduino, mechanical arm, robot, etc. have started to practice in foreign primary and secondary schools, but they may only have access to them in large cities in China. Children like the author who came out of the countryside have only found their interests here until now, but at present they can only learn and develop in their spare time. Now we can only hope that our children can contact similar products early and cultivate their interests!

Similar to uArm mechanical arm products, there are 7Bot and Dobot, which are probably the most popular at present. It is reported that the founder of 7Bot started his business from uArm project. So there is a certain inheritance between the two. No matter what products are, they start from imitation to technology accumulation and then to innovation and development. As far as I can see from the three websites, the information and software are probably the most complete, because from the information currently introduced, Dobot can achieve writing, painting, laser engraving and other actions, one of the most important parameters is that its repetition accuracy can reach 0.01mm, but at present the accuracy of uArm can only reach ± 5mm, which may be a big difference. Maybe the designers of uArm here want to achieve different functional goals.

Unpacking

This is the fastest time for me to experience the product Love to play computer games It was delivered by Shunfeng Express. I haven't experienced such a fast express for a long time. It took only two days from Shenzhen to Beijing. And when receiving the express delivery, I found that the product was not as big and heavy as I thought. The size was only the size of A4 paper, and the weight was about 1kg. After searching on the Internet, there are few articles about uArm at present, so I will open the box for you here:

The uArm box is slightly larger than A4 paper, which doesn't take up much space. A white coat is put on the outside to ensure that the box will not be opened unintentionally. At the same time, the black and white matching and the circuit design on the white coat indicate that this is a technological product.

The box can be pulled out from the side.

After removing the coat, you can find a plump black paper box. It seems that there are many things in it. Open the box below.

After opening the box, I found that there was a bag inside. It was very considerate, and the size was just enough to put the box in the bag.

The arm is wrapped with a plastic bag and supported by the frame stacked by the box. Since the main frame has been assembled, it can be used quickly. The power supply, air pump and bracket are respectively placed on the lower right side of the box through the box. All products are shown as follows:

It's considerate to have a screwdriver.

The purpose of listing these eight screws here is to show you that the quality of these screws is very good. They are not ordinary screws.

The USB data cable is a noodle cable, which has a good feel. At the same time, the connectors are made of metal, not our common plastic material.

These are four legs. They are very light in the hand. It seems that they are made of aluminum alloy, and the head is skid proof with rubber pads. The overall feeling is that the workmanship is exquisite. This is also the promotion of uArm products using CNC processing.

Appearance

The appearance of the arm. The arm does not sink when held in the hand. The structure is made of aluminum alloy processed by CNC. The processing is precise, and the screws are exquisite. This is my first impression of this equipment. But the steering gear is used, which may not be very precise.

The black ones on both sides are servo motors.

This is the detail of the nozzle. There is also a motor on the upper part of the nozzle that can control the nozzle to rotate 180 °.

Here are the data line interface and power interface. The design positions of data line interface and power supply interface may have poor contact of power line due to the air pump blocking the line when the manipulator rotates. At the same time, several days of experience found that the connectors of these two lines are relatively tight, which may be deliberately designed because the manipulator is constantly moving. Prevent poor contact.

The design of the base is very good. If you are afraid of instability, there is also a suction cup base, which can be more stable. I'm afraid the motor will burn out when the equipment goes crazy.

When I saw the steering gear, I felt cold. Maybe the mechanical arm could only do one action. High difficulty may not be completed.

The steering gear is on both sides, and the wiring condition.

Experience

With this mechanical arm, my children want to borrow it for fun. It seems that there are many geeks around me. For the trial of this mechanical arm, if you don't write some code, you are embarrassed to try it. So I have to write something. When I was writing something, I found a problem. I didn't know what the control protocol of this device was. I couldn't find it on the official website. Finally, I contacted the official customer service to get the information. But please note that the information here is all in English and only one document. Later, I found several examples in the example document, and realized the control of the manipulator through learning the examples. Such a process also goes through a long process, in which communication with the "hard man is king" who tried together makes the trial run smoothly.

At present, the official problem is the lack of some instruction documents, such as how to realize the movement, grabbing, alarm and so on of the mechanical arm through the code. As well as the software or APP that can teach, because some geeks just want to achieve some actions or draw pictures, in fact, I found that the code I wrote is to achieve some code actions by teaching.

Step 1: Use the official Uarm_Client.exe program for action control. First, this program is written in Java, so you must install the Java running environment when using it.

I found it. The English interface will still be used. Geeks should at least graduate from college. Of course, there are also junior high school cultures that can be recognized. ha-ha

The first step is to select the COM port in Setting, and then select Connect. At this time, Connect will turn yellow to prove that the connection is OK. You can click RESET to test whether the mechanical arm returns to its original position. As long as you connect it, you can control the movement of the device at various positions, as well as the adsorption and release of the suction nozzle. But this is just for control. You may feel that it is not interesting after several movements, because what we want is the automatic completion of the robot arm, which looks like a tall and tall robot. If you have Leap Motion, you can use Leap Motion to control your movements. If you don't have Leap Motion, you won't try it. It is available on JD. If you are interested, you can buy it.

Try the second step:

After the simple test of the above software, I thought about how to control the movement of the mechanical arm. However, because of the lack of protocol, I had to crawl the protocol through the serial assistant. After crawling, I found that it was all digital code, and I didn't understand it. Sending the next command through the serial assistant could achieve one or two simple actions, but it was far from enough.

The following commands are captured:

Air nozzle: adsorption F0 AA 1D 00 F7

Release F0 AA 1D 01 F7

initialization

F0 AA 1E 01 00 00 00 01 00 00 00 F7

If the order to move the position has a large section, I can't figure out what to do, and I am in a stalemate during the trial. I don't know how to use it. Later, the manufacturer sent Github's link, and found some example codes through searching. By understanding the codes, I was able to control the movement of the mechanical arm. Because I know Arduino, I burned the code of various examples and found that the code "Getting Started" can easily achieve movement. Therefore, my second trial was to use the command learned from this code to achieve the teaching action of the device, which can make the device perform some actions. However, these actions are all based on the command to first obtain the position coordinates of the current manipulator, and then burn the positions to be moved into the manipulator. This is only the first step of control. Later, after coding, you can enter Teach mode and record actions by entering Teach commands. Then, the device action is realized by entering the command move.

Code snippet for implementing device coach

+++++++++++++++++++++++++++++Code snippet for implementing device coach++++++++++++++++++++++++++++++

    if (readSerial == 't')
    {
      uarm.alert(1, 300, 100);// A long sound indicates the beginning of teaching
      for (int i = 0; i < 11; i++)
      {

        uarm.get_current_xyz();

       Teach_x_pos[i] = uarm.get_current_x();
        Teach_y_pos[i] = uarm.get_current_y();
        Teach_z_pos[i] = uarm.get_current_z();
        delay(5000);
        uarm.alert(i, 100, 100);// Record the number of times and sound several times

        Serial.print("The current location is ");
        Serial.print(i);
        Serial.print(Teach_x_pos[i]);
        Serial.print(" , ");
        Serial.print(Teach_y_pos[i]);
        Serial.print(" , ");
        Serial.print(Teach_z_pos[i]);

        Serial.println();
      }
    }

    if (readSerial == 'm')
    {
      for (int i = 0; i < 11; i++)
      {
        uarm.move_to(Teach_x_pos[i], Teach_y_pos[i], Teach_z_pos[i]);
        uarm.alert(2, 10, 100);// Record the number of times and sound several times
        delay(100);

      }
    }

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

Try Step 3

After the above trial, we found that there are still some small problems that have not been realized, namely, adding some actions and editing actions. This requires the upper computer to write. Fortunately, I learned C # by myself and wrote the upper computer with C #, so I still have some experience. Otherwise, serial communication will kill people. This is to write and record teaching actions. After the direction is set, start writing. In fact, the writing is very smooth. However, it took a long time to debug the interval between the action and the action, because it was impossible to judge whether the last action was completed. Therefore, it was impossible to know when to send the second command. The sending overlap led to incorrect device action. During the debugging process, various equipment "draughts" occurred, but I felt it was normal. Debugging! However, I would like to thank my daughter-in-law for not killing me, because I have been debugging programs for the past two days, so I have no time to play with my son. (My son came to Beijing only in the summer vacation, and usually he seldom spent time together.)

A great god said that programmers spend 20% of their time thinking about how to write code, 15% of their time writing code, and 65% of their time debugging programs. It was found that it took a long time to write code. But now the function has been realized and can move. However, after the success, we found that there was a certain error in the perception that the equipment did not reach the position at the end of the teaching coordinate. I don't know why? It feels like the Offset value, but after testing several values, it is not. Fortunately, now the action is finished.

The above figure is the interface of a software I wrote. The functions currently implemented can teach the robot arm actions, and the operation steps are as follows:

Step 1: click the motor to power off, then you can move the arm.

Step 2: Move your arm to the target position you want, then click Get Position, and then receive the position coordinates in the receive information box.

Step 3: click Add Position to add the currently obtained coordinate position to the running step.

Step 4: click the action you want, such as nozzle rotation, nozzle adsorption and other actions.

Step 5: Save the running step to the file.

Step 6: click motor power on.

Step 7: Click Run, and the mechanical arm will start to move.

Note that the serial port switch can only be connected twice.

Then you can move the robot arm according to your own ideas.

Then you can download and modify if you want to change.

Test

In order to test the ability of this mechanical arm, the author made the mechanical arm write a letter "A" according to the teaching of several points, and repeated the positioning of the mechanical arm several times, which is still relatively accurate, but when walking in a straight line, the bending phenomenon will be fixed in a certain direction. It can also reach within 5mm of the nominal value.

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At the same time, the mechanical arm will shake when it rotates.

Summary

It's time to make a summary. I pay attention to the video of this robot arm on the Internet. At the same time, I understand that this product is mainly for sales abroad. Some information is written by foreign geeks. At present, the manufacturer is trying to sell it in China. But first, a group of geeks need to develop some applications and instructions to expand the application of the product. The author is a beginner. In order to use this manipulator as soon as possible and conveniently, the author has developed a software that can be used for learning. But it must be completed through the upper computer.

Now let's talk about the advantages and disadvantages of this robot arm. It has been tried for about 20 days. This is a long trial. The trial time of such a highly open product cannot be equal to that of other products. It needs to develop code to use it, At the same time, there are no instructions and tutorials for domestic development of this product. Therefore, I was looking for tutorials and interface files for a long time.

advantage:

1. The workmanship is absolutely exquisite, because the CNC processing is used, and the screws are not ordinary screws.

2. The accessory data line is exquisite.

3. Products are advantages. But the supporting facilities are just shortcomings.

4. The official customer service communicated actively and was able to promote data acquisition.

5. Considerate, equipped with suction cup base, it is convenient to graft the mechanical arm onto other objects, such as mechanical control trolley.

Disadvantages:

1. There are no domestic product descriptions and tutorials.

2. Since geek debugging may have wrong code, which may lead to abnormal arm, it is recommended to add emergency stop button to prevent arm damage.

3. At present, the mechanical arm using steering gear shakes severely when rotating. It may not reach the set coordinate position due to algorithm problems, but these can be changed through upgrading. It is reported that the manufacturer is in the process of upgrading.