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Drivetrain Design 1. Unit 9. Drivetrain Turning. Most common type is a skid steer which is often called a tank drive . Consists of 2 sets of wheels on each side of the chassis with each set running at different speeds. - PowerPoint PPT Presentation

Transcript of Drivetrain Design 1

Drivetrain Design 1

Drivetrain Design 1Unit 9Drivetrain TurningMost common type is a skid steer which is often called a tank drive. Consists of 2 sets of wheels on each side of the chassis with each set running at different speeds. This allows the robot to steer in arcs and is also capable of a zero radius turn.

Drivetrain TurningThere are 2 properties of drivetrain turning:Turning torqueScrub torqueTuring Torquethe wheels on the left and the right of the robot are the drive wheels and the wheels on the front and the back are used for stability.When the right wheel moves forward, the left wheel moves in reverse. This will cause the robot to move left. The force of the wheels provides the torque at the center of the robot.

Scrub TorqueFor a robot to turn, the front and rear wheels need to slide sideways across the floor causing friction between the wheels and the ground. This friction opposes the turning of the robot and is called the scrub torque. If a robot is to turn, the turning torque needs to exceed the scrub torque.

How Can You Reduce the Scrub Torque?Reduce the wheel friction with the ground. Change the normal force or the weight of the robot.Change the coefficient of friction of the wheel itself. 2. Reduce the size of the center of rotation. a. Change the configuration of the chassis. How Can You Increase Turning Torque ?Increase the turning force of the wheel.Increase the normal force.Increase the coefficient of friction.2. Increase the distance of the center of rotation of the robot.a. Change the configuration of the chassis. This drivetrain is short and wide. This robot will have good turning because of its high turning torque and low scrub torque.

This drivetrain is long and narrow. This robot will turn poorly because of its low turning torque and high scrub torque.

SummaryTo make a robot turn better, adjust:The chassis configuration.The difference in traction between the various wheels (mainly the front and back wheels). Unit 9 TasksTHINK Phase lecture notes and keytermsBUILD Phase pp. 25-42AMAZE Phase Challenge p. 44Eng Notebook p. 45STEM Science #1, 2; Tech #1, 3; Eng #1-4 Unit 10 TasksTHINK keyterms. Read pp. 7-23. BUILD pp. 24-25. Use the Engineering Design Process. Outline the 7 steps found in the Unit 3 lecture. This will be submitted as your Engineering Notebook.AMAZE Challenge p. 28Eng Notebook Eng Design Process from BUILD Phase.STEM Science #1,2; Tech #1-3