Chess Robot - Set Up

geraldinebc15 · November 20, 2020, 10:15am

In this tutorial we detail how to prepare everything and also share some tips to make the perfect setup.

This is a companion discussion topic for the original entry at https://community.robotshop.com/robots/show/chess-robot-set-up

cbenson · December 1, 2020, 1:16pm

This seems to be timed perfectly for Netflix’s series "The Queen’s Gambit.

geraldinebc15 · December 1, 2020, 3:50pm

Hahaha yes!

My sister started watching it last week and said it is really good, and she isn’t even into chess.

Gunnar86 · February 23, 2021, 3:31am

Can the AL5D robot arm be substituted for the LSS robotic arm?

geraldinebc15 · February 23, 2021, 11:07pm

Hello @Gunnar86!

You could use the AL5D arm, however, you would have to modify the code because the AL5D arm doesn’t use the LSS smart servos, these communicate using the LSS serial protocol which is what is used in the project and it doesn’t work for regular servos.

Anyway if you are interested in making it work for that arm here I shared some tips that may be useful.

You could also contact Solomon because he seems to have the same interest as you. It would be great to be able to modify the project to work with the AL5D!

Let me know if you have any other questions

Gunnar86 · February 23, 2021, 11:57pm

@geraldinebc15

Thank you for quick response! At this point, I am looking into using the existing code and modifying it. I am also interested in replacing the AL5D servos with the smart servos so if you have any additional advice that would be great! I have raspberry 3 starter kit, is that sufficient or would you recommend the raspberry 4 b?

geraldinebc15 · February 24, 2021, 8:38pm

I am also interested in replacing the AL5D servos with the smart servos

Unfortunately, this isn’t possible because the two arms use very different parts (mechanics, electronics and servos) (AL5D uses the SES V1 and the LSS Arm uses the SES V2). However, if you have the AL5D version with the SSC-32 or SSC-32U they have a protocol that overlaps so the code can potentially be adapted (if you don’t make use of the “smart” aspects of the system). For example, instead of using the Degree command (#1D450), you could use the Pulse command (#1P1000) where the number for the pulse corresponds to the angle (moving a servo to 45.0 degrees would be a pulse of 1000us). In case you are interested, you can check both communication protocols here:

http://www.lynxmotion.com/images/data/lynxmotion_ssc-32u_usb_user_guide.pdf (page 24)
However, if you were already planning on investing in the smart servos a good option would be simply getting the 4DoF arm as this would be “plug and play” and you could save a lot of time, but it is up to you

I have raspberry 3 starter kit, is that sufficient or would you recommend the raspberry 4 b?

For sure, you can easily use a RPi 3 instead.

Gunnar86 · May 9, 2021, 1:53am

Are there any python libraries I can import from the AL5d code?

geraldinebc15 · May 10, 2021, 4:44pm

Not a library per se but there are some sample codes:

Python:

github.com

Lynxmotion/Arms/blob/master/Code examples/Python (RPi)/Basic 2D IK example/lib_al5_2D_IK.py

# 2017-07-12 by scharette
# Basic 2D IK example of AL5 + Python (library)

from math import sqrt, atan, acos, fabs

# Define legnth of AL5 sections
# if AL5A
#A = 3.75;
#B = 4.25;

#if AL5B
#A = 4.75;
#B = 5.00;

#if AL5D
A = 5.75;
B = 7.375;

# Constants
rtod = 57.295779	# Radians to degrees constant

This file has been truncated. show original

Arduino:

github.com

Lynxmotion/Arms/blob/master/AL5D/Arduino_Arm/Arduino_Arm.ino

    #include <Servo.h>
    #include <PS2X_lib.h>

  #define SOUND_PIN    5        // Botboarduino JR pin number
  #define PS2_DAT      6        
  #define PS2_CMD      7
  #define PS2_SEL      8
  #define PS2_CLK      9

    PS2X ps2x;
    int error = 0;
    byte type = 0;

    #define Deadzone 10

    char ArmSize = 'D'; // Must be 'A', 'B', or 'D'  DO NOT REMOVE THE SEMICOLON OR THE ' '
    float A;
    float B;
    float rtod = 57.295779;

This file has been truncated. show original

PS: @Solomon123 is also working on modifying the code to work with the AL5D so you may want to reach out to him.

dancrissco · July 4, 2022, 9:29pm

I am having a Math Domain Error after the first manual move

geraldinebc15 · July 5, 2022, 2:12am

Hello @dancrissco!

Did you set the dimensions in inches? If you did make sure it is possible to reach the desired position with the arm.

For reference these are the dimensions I used:

{“baseradius”: 1.77, “cbFrame”: 0.62, “sqSize”: 1.09, “cbHeight”: 0.79, “pieceHeight”: 1.97}

dancrissco · July 5, 2022, 7:56am

Thanks for your reply Geraldine.
I had my cbframe as 10 inches.
What is cbframe?
I thought it was one side of chess board. My mistake.
Here are my parameters
{“baseradius”: 2.0, “cbFrame”: 10.0, “sqSize”: 1.25, “cbHeight”: 1.0, “pieceHeight”: 1.5}
Regards
Daniel

geraldinebc15 · July 5, 2022, 4:27pm

cbframe means chessboard frame, so in this case, it would be what is marked in red:

dancrissco · July 5, 2022, 7:32pm

Hi Geraldine. It is working now. I made a few chess moves to check it out. Will now work on it to make the movement smooth and repeatable. Once again thanks for the help.

cbenson · July 5, 2022, 7:50pm

@dancrissco We hope you might be up to providing a video of your progress here! Happy it’s working!

dancrissco · July 13, 2022, 12:26pm

The chess robot works well for about three moves and then comes with an invalid move announcement.
This happens after I have moved the chess piece. Kindly advise.
Screen shot of the code area is provided. Is this vision related?

geraldinebc15 · July 13, 2022, 12:52pm

A nice way to find out if this is what is happening is by adding some lines to the code you screenshotted to show the "prevIMG and “curIMG”. However, it is most likely that the picture is being taken when your hand is on the chessboard, please make sure that you wait until the robot is resting in its place, make your move, and press the clock when your hand is not on the way.

Let me know if that works

dancrissco · July 13, 2022, 2:01pm

Thanks Geraldine. I will try that.
Regards
Daniel

dancrissco · July 13, 2022, 4:21pm

Hi Geraldine, the issue is when the robot picks the Bishop or Knight. It misses or topples adjacent pieces.
This causes the invalid move
The picking of pawns is clean. Wondering if I should play with gripper angle or open close?
I think the key now may be to master the robot pick and place.
Any suggestions?

tepalia02 · July 14, 2022, 7:34am

Thanks for the detailed tutorial. Must try someday.