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Robot Arm not moving correctly  

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7bdb6d27754f49646bd53724440824e5?s=80&d=mm&r=g
(@iseries1)
Active Member
Joined: 4 years ago
Posts: 14
02/10/2020 3:58 pm  

I just assembled the robot and everything went together well. Have several left over screws and nuts though.

Had issues compiling the firmware as it wanted that Laser range finder, VL53L0X, which I do not have. Just commented out all the references and it compiled just fine.

Running the python code revealed a number of issues. First the robot does not move like the screen shows. The motors are backwards or something. In the assembly section one pictures show the motors connected with the Blue wire to the left and the next picture after that shows the Blue wire on the right. Which is it?

Can’t figure out how to get the robot to move up and down using the python code. I think we need a video of the software in action to determine if there is something wrong.

When I hit calibrate it leaves the robot arm either all the way left or all the way right depending on how I have the motors wired. It does not put it in the center as the picture shows. Also the Open/Close function does not work at all. When I power on the unit the claw opens and closes but the Python code does nothing nor does it rotate the claw except in absolute mode.

Great software just can’t make it work….

Mike


After further investigation I saw that I had motors 1 and 2 reversed. I guess I need to place a label on the top side so that I don’t have to look at it upside down to determine which is motor 1 and motor 2. Doing this make the robot go to the center position and not all the way to the left or right.

Also looks like the motors are plugged in with the Blue wire to the right.

So now the robot arm moves correctly and to the correct positions most of the time there are some position from and too that cause the robot to not move correctly. I also found that using the scroll wheel on the mouse moves the arm up and down.

The only item not working is the Open/Close function for the claw and how do you turn the claw.

Mike


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7bdb6d27754f49646bd53724440824e5?s=80&d=mm&r=g
(@iseries1)
Active Member
Joined: 4 years ago
Posts: 14
02/10/2020 7:53 pm  

Well after some more trial and error I got the gripper to work. The program documentation though is backwards.

This is what’s in the code:
Servo servo1; // Wrist orientation
Servo servo2; // Gripper open/close

I think this should be the other way around.

Also in the configuration file it has this:
// Servo definitions
// Servo1: Wrist orientation
#define SERVO1_NEUTRAL 1500 // Servo neutral position Gripped angle
#define SERVO1_MIN_PULSEWIDTH 800
#define SERVO1_MAX_PULSEWIDTH 2200
#define SERVO1_RANGE (SERVO1_MAX_PULSEWIDTH-SERVO1_MIN_PULSEWIDTH)

// Servo2: Gripper
#define SERVO2_NEUTRAL 1500 // Servo neutral position
#define SERVO2_MIN_PULSEWIDTH 1100
#define SERVO2_MAX_PULSEWIDTH 1900
#define SERVO2_RANGE (SERVO2_MAX_PULSEWIDTH-SERVO2_MIN_PULSEWIDTH)

This looks also backwards.

Also there is not a motor release function. It states that the stop function disables the motors when they are not so it is not possible to move the motors freely once that button is pushed. Would be nice to have a release function so that the motors could be repositioned if necessary.

Mike


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350a26dd49eb55d3494500240423a207?s=80&d=mm&r=g
(@robotn1)
Honorable Member Admin
Joined: 5 years ago
Posts: 688
06/10/2020 2:35 pm  

I just assembled the robot and everything went together well. Have several left over screws and nuts though.

Had issues compiling the firmware as it wanted that Laser range finder, VL53L0X, which I do not have. Just commented out all the references and it compiled just fine.

Running the python code revealed a number of issues. First the robot does not move like the screen shows. The motors are backwards or something. In the assembly section one pictures show the motors connected with the Blue wire to the left and the next picture after that shows the Blue wire on the right. Which is it?

Can’t figure out how to get the robot to move up and down using the python code. I think we need a video of the software in action to determine if there is something wrong.

When I hit calibrate it leaves the robot arm either all the way left or all the way right depending on how I have the motors wired. It does not put it in the center as the picture shows. Also the Open/Close function does not work at all. When I power on the unit the claw opens and closes but the Python code does nothing nor does it rotate the claw except in absolute mode.

Great software just can’t make it work….

Mike


After further investigation I saw that I had motors 1 and 2 reversed. I guess I need to place a label on the top side so that I don’t have to look at it upside down to determine which is motor 1 and motor 2. Doing this make the robot go to the center position and not all the way to the left or right.

Also looks like the motors are plugged in with the Blue wire to the right.

So now the robot arm moves correctly and to the correct positions most of the time there are some position from and too that cause the robot to not move correctly. I also found that using the scroll wheel on the mouse moves the arm up and down.

The only item not working is the Open/Close function for the claw and how do you turn the claw.

Mike

We use to send more bolts and nuts than required. Just in case the customer need them.

Regarding the laser: If you install all the listed Python libs, you will not get any problems but , of course, if you do not want to use it, you have to comment some lines out. We opted to include them all to avoid problems with users who got the kit with the laser

Check if motor 1 and 2 are placed correctly. That may be the source of the problem with the arm moving backwards

From the control App (Python) you can move the robot up/down using the mouse´s wheel.

Ok… I just read that you had the motors placed “backwards” 😛
Moving the clamp: check you have connected the servos to the right ports. or that any of them are stuck


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350a26dd49eb55d3494500240423a207?s=80&d=mm&r=g
(@robotn1)
Honorable Member Admin
Joined: 5 years ago
Posts: 688
06/10/2020 3:03 pm  

Well after some more trial and error I got the gripper to work. The program documentation though is backwards.

This is what’s in the code:
Servo servo1; // Wrist orientation
Servo servo2; // Gripper open/close

I think this should be the other way around.

Also in the configuration file it has this:
// Servo definitions
// Servo1: Wrist orientation
#define SERVO1_NEUTRAL 1500 // Servo neutral position Gripped angle
#define SERVO1_MIN_PULSEWIDTH 800
#define SERVO1_MAX_PULSEWIDTH 2200
#define SERVO1_RANGE (SERVO1_MAX_PULSEWIDTH-SERVO1_MIN_PULSEWIDTH)

// Servo2: Gripper
#define SERVO2_NEUTRAL 1500 // Servo neutral position
#define SERVO2_MIN_PULSEWIDTH 1100
#define SERVO2_MAX_PULSEWIDTH 1900
#define SERVO2_RANGE (SERVO2_MAX_PULSEWIDTH-SERVO2_MIN_PULSEWIDTH)

This looks also backwards.

Also there is not a motor release function. It states that the stop function disables the motors when they are not so it is not possible to move the motors freely once that button is pushed. Would be nice to have a release function so that the motors could be repositioned if necessary.

Mike

I will check the “disable motors function” with Jonathan today (in charge of the software). Thanks for the feedback Mike!


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7bdb6d27754f49646bd53724440824e5?s=80&d=mm&r=g
(@iseries1)
Active Member
Joined: 4 years ago
Posts: 14
08/10/2020 12:50 pm  

This is a great project and I think the feature of the robot should be expanded on. You should talk about how the stepper motors that control the Arm and Elbow convert steps to an angle to position the robot in X and Y coordinates. I ended up looking it up on the internet but I think it helps sell the project.

Mike


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