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Mecanum Drivetrain Options

6″ Mecanum VersaChassis

One of the most important aspects of designing a robot this season is how teams construct their drivetrain. This 6″ Mecanum VersaChassis includes many of the recommended features from this year’s Drivetrain Design Guide, like side-to-side (holonomic) motion, a proper angle of approach to traverse the Scoring Platform, and a slower overall speed than in past years. This Mecanum VersaChassis was made to be a base for teams to start building their own robot on. Our recommended gearing calculations are posted below.

 

6″ Wheel with Belt Drive

The Single Reduction Clamping Gearbox naturally pairs with a Plastic Clamping Bearing Block or VersaBlock to establish a standard drivetrain gear reduction. For those who wish to use a 6″ wheel, VEXpro HTD belts & pulleys can be used to achieve the same result. Download the STEP file for this Application Example here.

217-4156-6in-Wheel-Application-rev2

 

4-Bar Simple Stacker

The formerly mentioned 4-bar is now complete! We are excited to see what kind of mechanisms teams can come up with to attach to this 4-bar. After prototyping this 4-bar simple stacker, it is confirmed that it is able to lift itself a minimum of 19 inches to be able to stack Totes on the Scoring Platform.   This system is very adaptable and could merge well with the Pinch Claw or any other object manipulation systems teams come up with!

4-bar

Click to download CAD file (STEP, 44.3 MB)

Claw Design Guide

Object manipulation is very important for this year’s game, Recycle Rush.  The Pinch Claw group developed this Claw Design Guide to elaborate on the variety of mechanisms to consider for your robot this year.  Read an excerpt of the 2015 Build Blitz Claw Design Guide:

“Due to the nature of competitive robotics, nearly every game involves some sort of object manipulation. Whether it’s picking up an object and placing it on a goal or gripping onto a field element, claws are an extremely common method of object manipulation that most teams consider at some point during their design process. Claw designs can be as varied as overall robot designs, but most fall under one of three categories: roller claws, pivot/pinch claws, and passive/fixed claws. The purpose of this design guide is to introduce these three primary styles and to help teams evaluate the best manipulator for their needs.”

 

Download the full VEXpro Build Blitz Claw Design Guide here!

claw-cover

Drivetrains for Recycle Rush

One of the Build Blitz teams devoted their time to the various possibilities of drivetrains for Recycle Rush.  Read an excerpt of the 2015 Build Blitz Drivetrain Design Guide:

There are a lot of factors which need to be considered when designing a drivetrain for the 2015 game. Refreshingly, a few of the “historical” constraints have been removed. In addition several aspects of the game may shift a team’s traditional design requirements. This is cool because it forces designers to discount their pre-conceived notions and it provides a fun thought exercise. We love fun thought exercises!

Lots of people ask “what do you recommend for this year’s game?” The answer is always: the simplest drive that does everything dictated by your strategy. (See Karthik’s Strategic Analysis). In our minds this probably means the following for most teams:

      • Moving sideways is very helpful when trying to align & stack Totes
      • Stick to a “traditional size” base — just because the rules allow for giant robots doesn’t mean it is a good decision
      • If you’re gearing faster than 10 ft/sec free-speed, you’re probably going too fast
      • You should try to find a configuration which crosses the scoring platforms; using 6” diameter wheels is a simple way of accomplishing this
      • Focus on reliability — you need to maximize every match, not just “escape with the win”.

Whatever you choose to do, focus on that last point. Consistency is critical in 2015. Good luck to all teams! Send any comments or questions to prosupport@vex.com for more help.”

Download the full VEXpro Build Blitz Drivetrain Design Guide here.  We can’t wait to see what ideas you come up with!

ddgcover

Pinch Claw – Final Testing

We have our first functional prototype – the Pinch Claw! This morning the Pinch Claw group was finished building and ready to test their mechanism. First, the claw was tested grabbing a Tote and placing it on another Tote. Every time this was tested, the claw was successful.

Next, the claw was tested to grab a Container and place it onto a Tote. The initial tests were unsuccessful because the Container was too slick for the grabber to lift up. After adding friction material (in this case, black gum rubber) to the sides of the claw, there were no issues lifting and placing a Container on top of a Tote.

The complete Pinch Claw was made out of all VEXpro parts and weighs 4.5 lbs. The only complication the group ran into was having to add friction material (in this case, black gum rubber) to grip the Container. Prototyping is very important for every team – your mechanism doesn’t need to be attached to a fancy robot to see if it works or not. This Pinch Claw is very versatile, and can attach to almost any other mechanism to complete a robot.

Linear Elevator Concept

Tonight we got a chance to sit down and talk with Lead Engineer of the Linear Elevator group, Art Dutra. Take a look at how a linear elevator is an efficient way to score in Recycle Rush, and get a sneak preview of some NEW VersaFrame parts being created to help teams create an elevator of their own!

Linear Elevator on Field Linear Elevator Close-Up

A Simple Stacker Begins to Take Shape

This morning we got an update from the Simple Stacker group. They have been busy working on a 4-bar system to complete this crucial task. The goal for this mechanism is to be able to stack two totes on top of the step – ultimately using this to assist in gaining the Coopertition points.

Initially, a 4-bar was compared to a linear elevator system, but 4-bar required less precision alignment.  Additionally, even though both styles achieved the same goal, a 4-bar would be much simpler to design and construct.  As highlighted in Karthik’s Strategic Analysis, this is always an important factor to consider.

To reach this goal, the 4-bar stacker needs to be able to lift itself 19 inches from the ground up to reach the height of 2 Totes on top of the Step. It achieves this in early calculations.

Lift lowered grabbing bin  Lift Raised stacking on step

After completing the 2D prototype, the group decided on using a Mini CIM and a VersaPlanetary Gearbox to power this stacker. After some quick calculations, it looked like a Mini CIM would work perfectly.  Thanks to its compact size and ease of use, the VersaPlanetary Gearbox was the natural interface between the motor and the linkage.

Gearing calculations

The next step for the Simple Stacker group will be to turn their 2D “Crayola CAD” into a 3D CAD model for more testing. We can’t wait to see how their process continues to grow!