Introduction: 3 Wheel OmniCone
"This instructable was created in fulfillment of the project requirement of the Makecourse at the University of South Florida (www.makecourse.com)"
Say hello to the latest idea in soccer training equipment.
Designed to add a challenge to all aspiring dribblers. Do away with boring static cones that are easy to dance around and add the OmniCone to your training routine to improve reflexes and on the fly decision making.
Unleash your inner Messi. . .
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Step 1: Designing the Cone
The design of the cone is split into a 3 part structure.
1) The base module that holds the motors, wiring harness and the mounting brackets.
2) The base of the cone that holds the electronics. (Arduino UNO, WickedDevice motor shield and the radio receiver)
3) The top of the cone that completes the cone and provides protection during use. It can further be used to house additional modules like proximity sensors, cameras and LED's.
Step 2: Assemble the Designed Parts
Using inventor, constrain the individual pieces to form the final design.
Step 3: Add Mounting Brackets and Omniwheels.
Omniwheel mounts: https://bit.ly/2E9aHfc
60mm OmniWheels: https://bit.ly/2E9aHfc
Find the right size mounting brackets for the base. The wheels must be angled 120 degrees from each other and the holes to mount the motors must match the holes on the motor itself.
Screw in the motor brackets using regular wood mounting screws.
Make sure the wires for the DC motors are soldered in place before mounting them on the brackets.
Add the omniwheel hub to the motor shaft.
Add the wheels and screw into place tightly.
Step 4: Add Electronics
Motor shield: https://bit.ly/2UolRTe
Add the motorshield to the Arduino.
Connect to motors to the motorshield at the correct ports. The user manual is a good source of information and gives various specifications on modes of operation.
Connect the radio receiver to the motorshield and program it to connect to the transmitter.
Mount the complete electronics bundle using double sided tape.
Step 5: Add the Cone Halves
Using zipties connect the two halves of the cone. This protects the electronics from damage during use in soccer practice.
Mount the base of the cone to the top of the base module using screws. Alternatively a hinge can be added to allow for easy access to the electronics for troubleshooting.
Step 6: Program the Arduino
Program the arduino to accept radio inputs from the receiver on the motorshield and convert it into control vectors for the motor driving outputs.
We use the PWM outputs from the arduino to drive the DC motors.
The formula to calculate these vectors is derived from trigonometry.
The first wheel is parallel to the axis of motion and is a cosine of the angle at which the motors are set. In this case it is cos(120). This is multiplied by a magnitude vector that governs how fast the robot will travel. This gives us a value V1. the negative of this value is fed to the first motor.
[wheel1 = –V1]
The second trig component is the sin component. In this case V2=sin(120).
Using a combination of the sin and cos values gives us.
wheel2 = 0.5 * V1 – √(3/2) * V2
w3 = 0.5 * V1 + √(3/2) * V2
This is the calculation that the arduino does on the fly depending on the input from the receiver.
The rest of the programming involves polling the receiver and sending the PWM output to the motors.
Additional functions such as proximity sensors to activate the robot can be added as well.