Calculating Velocity of Lego EV3 Large Motor in a Projectile Motion

The EV3 Large Servo Motor is a powerful motor that uses tacho feedback for precise control to within one degree of accuracy.

By using the built-in rotation sensor, the intelligent motor can be made to align with other motors on the robot so that it can drive in a straight line at the same speed. It can also be used to give an accurate reading for experiments.

The motor case design also makes it easy to assemble gear trains.

Specifications:

• Tacho feedback to one degree of accuracy;
• 160-170 rpm;
• Running torque of 20 N/cm (approximately 30 oz/in.);
• Stall torque of 40 N/cm (approximately 60 oz/in.);
• Auto-ID is built into the EV3 Software.

Combining knowledge from projectile and getting the velocity of the rotating body such as EV3 large motor can lessen your trial and error with your robot.

Using the formula of V = 2rN or DN .

• V – velocity of the body rotating m/s
• r – radius of rotation
• D – diameter of rotation
• N – no. of rotation/revolution per minute

Sample

A 50g Blue ball will be thrown in a plain field with an angle of 45 degrees. Using the large motor with a 170rpm (max) how far will it go if the throwing arm has a length of 100mm.

Using the formula above in getting the initial velocity that will be applied to the Ball

V = 2 (3.14)*(0.1m)(170rev/min)

V = 106.8 m/min

V= 1.78 m/s

Using this V as the initial velocity of the object in projectile motion, we can get the maximum distance it can reach using the formula

R = V² x sin2(Ø) / g

R = (1.78m/s)² x sin2(45)/9.81m/s²

R = 0.507m

Note that If we decrease the value of rotation of the large motor, we also decrease the peripheral velocity of the object and shorten the distance it will travel.