How The Gripper Test Works

How test_gripper_angles_buttons Works

After importing the cyberbot module, the script uses display.show(Image.ARROW_E)  to point at the micro:bit module’s B button.  

# test_gripper_angles_buttons

from cyberbot import *

display.show(Image.ARROW_E)

The main loop repeatedly checks if either the A or B buttons have been pressed.  If the B button was pressed since the last time it checked, the bot(16).servo_angle(30) call closes and lifts the Gripper paddles.  If the A button was pressed since the last time it checked, the bot(16).servo_angle(150) call lowers and opens the Gripper paddles. 

Both servo_angle calls can be considered “set it and forget it” so the servo will hold the position it was most recently set to.  Whenever a particular button is pressed, the arrow is updated to point at the other button.  

while True:
    if button_b.was_pressed():
        bot(16).servo_angle(30)     # close gripper & lift
        display.show(Image.ARROW_W)
    elif button_a.was_pressed():
        bot(16).servo_angle(150)    # Lower gripper & open
        display.show(Image.ARROW_E)    

Try This

Some objects need to be lifted up and set down more carefully, like objects with narrower bases.  Try modifying the test script to make the Gripper close-lift and lower-open more gradually.  

• Set the project name to test_gripper_angles_buttons_try_this.  
• Modify the script as shown below.  
• Make sure to change was_pressed to is_pressed in the if and elif conditions.
• Save your work by clicking Save.
• Click Send to micro:bit.
• Make sure the batteries and barrel plug are connected and that the cyber:bot board’s PWR switch is set to 2.
• Test by holding the B button until the gripper goes all the way up, and then holding the A button until the gripper goes all the way down and opens.