Joint Control

1. The joint index
2. The joint control blocks
3. The balance blocks

CONTENTS

https://youtu.be/6euhRYrWdRY?si=6jIPs83Vut1t-fdM

Video

• In the last class we learned the basic structure of graphical programming
• In this lesson, we will learn about joint control so that Bittle can do various actions

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Thinking & Analysis

• We learned about the loop structure that makes sounds and lights.
• Our next task is to teach Bittle to shake hands.
• Think about how a person shakes hands.
• How does Bittle move each joint?

Sport

Center

Welcome to the Sport Center. Let’s understand Bittle’s servo first.

• Observe the joints of Bittle
• Does anyone know what components are connecting Bittle's joints?

Servo

• Servo is short for servo motor
• It is composed of DC motor, reduction gear group, and feedback control loop
• Generally, position control is used
• The angle range of Bittle’s servo Bittle is (0°~270°)

Joint Index Number

* Some joints are omitted on Bittle

• A block containing a joint index number and an absolute angle value

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• A block containing a joint index number and a relative angle value

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• A list consists of one or more pairs of joint index + absolute angle value

One time Joint Movement State

• Rotate individual joints to an absolute angle
• Rotate individual joints to a relative angle
• Rotate multiple joints sequentially to absolute angles or relative angles
• Rotate multiple joints sequentially to a list of absolute angle values

Sequential Transform of Joints

Simultaneous Transform of Joints

• Rotate multiple joints simultaneously to absolute angles or relative angles
• Rotate multiple joints simultaneously to a list of absolute angle values

You can set the delay time so that the robot can pause after finishing the current motion

• A list consists of the full frame (16 absolute joint angles)
• Rotate multiple joints simultaneously to the full frame
• Example:

Make Bittle / Bittle X stand up:

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Simultaneous Transform to a Frame

Example:

• Get the current angle value of the right front arm.
• Rotate the head joint to the value and delay 1.2s.

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Get a Certain Joint Angle

Call Preset Skills

• The gyroscope (gyro) can help the robot keep balance and recover when falls over.
• The balancing adjustments may interrupt your programmed motions.
• In Mind+ mode, the gyro sensor is automatically disabled.
• In Standard mode, the gyro is enabled. So it’s better to turn it off with the “Deactivate Gyro” block.

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The Gyro Block in Mind+

The “Deactivate Gyro” block must be put after the “open serial port block”

Task 1

Please write code to achieve the following requirements:

1. Rotate Bittle’s head from -30 degrees to 30 degrees gradually
2. Rotate the head from 30 degrees to -30 degrees gradually
3. Simultaneously turn the left and right rear thighs to 90 degrees, and left and right rear legs to -30 degrees
4. Sequentially turn the left and right front thighs to 50 degrees
5. Simultaneously turn the left and right front shank to 30 degrees

Task 1

Task 2

• Please write code to perform the following movements in order：
• Stand up
• Sit down
• Say Hello (3 times)
• Loop over the above actions

\CODE\3.02_JointsAction.mp

• Now we are quite familiar with joint control in Mind+.
• Next time we will create new skills in the Skill Composer.

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Now we have learned programming basis.

Next time we'll help Bittle master more skills in Skill Composer.