✔ Introduction ✔ Frame Build Motion Power Control Sensors Project evaluation

Motion STARTER Parts list Quick task: Discuss in pairs all the parts shown. Agree the function each of these parts for the Tumbler motion, and write your description in your parts list. 2-Wire-269 Motor Shaft Collars 4.6mm Spacers Motor Controller 29 3" Drive Shafts 5" Wheel

Creating Motion Learning objective: Understand how motion is created in robotics and how different types of motion can be achieved. Gears VEX uses a four-sided polygon (square) shaft as part of its motion system. This means that the shaft will transfer torque directly to anything which has a matching square hole.  This square shaft also has rounded corners, which allow the shaft to spin freely in a larger-size round hole.  The most common type of gear used in VEX robotics is called a spur gear. Spur gears transfer motion between two shafts running parallel to each other.  Spur Gears are characterized by their teeth, which are straight and parallel to the gear’s axis of rotation.  These are the primary form of mechanical power transfer used in the VEX Robotics Design System.

Rotational motion Creating Motion To begin, your motors will create rotational motion. By inserting a square shaft into the corresponding hole, you can drive anything (like the gears just seen) round and round.

Creating Motion Gear Chains The driver gear is the central gear here. It is driving the other two using a motor. The gears either side rotate in the same direction, and allow the two wheels to drive the Tumbler forward using one motor on one side. You can keep adding gears in pairs, to keep the wheels moving in the same direction

Creating Motion Task: Note these definitions down FRICTION is the force that opposes motion when two surfaces rub together.  It is a reaction force only.  It occurs when two surfaces are in contact and a force is applied such they slide along one another.  TRACTION can be defined as the friction between a drive wheel and the surface it moves upon. It is the amount of force a wheel can apply to a surface before it slips.  Increasing Traction: Since traction is dependent on the friction between the wheel and the surface, to increase traction one must maximize this friction. To increase traction, one must either increase the coefficient of friction (grippier wheels) or increase the normal force acting on the wheel (heavier robot, or more weight on drive wheels).

Creating Motion View the Step by Step build guide - MOTION Follow the instructions on page one of the build guide. Use the tools provided by your teacher and remember to check all the time that you are being accurate and working as a team! Key to getting it right… Fit the shaft couplers into each motor before fitting the motor to the chassis. Use one long screw and one short screw to attach the motors to the frame. Fit the collar to the shaft in the right place to prevent the shaft slipping.

Summary Today you have: Learning objective: Understand how motion is created in robotics and how different types of motion can be achieved. Today you have: Developed an understanding of how motors and attachments can change the direction of motion Explored gears Discussed in context the terms traction and friction.