Project Overview  Introduction  Clawbot Build  Design Modification  Design Development  Programming  Sensors  Advanced Sensors  Open design challenges  Project evaluation

LESSON 03

LESSON 3 STARTER Key words: Programmable, environment, design, manufacturing and application Learning objective: Analyse a finished product and evaluate its performance during a task. Develop a range of design modifications as sketches. Compare and objectively review modifications before improving a product. Task: Identify the faults Your 5 minute starter task is to operate the Clawbot (either over a competition field or on the floor/work- surface of your classroom) and identify three design features of the robot, that could be improved to help it meet its design brief better: “Design Brief The Robot will be designed to be easy to operate, will be able to collect bean bags from the ground and dispense them into a high scoring trough with ease, and will always remain upright during driver control.”

Redeveloping a product Feedback – What are the design faults? In your teams, agree the three main design faults you believe will stop the Clawbot from meeting its design brief? Decide their order or priority by scoring them with either 1, 2 or 3. 1 will be the most pressing issue, 3 the least. If the arm extends to its farthest position backwards, the motor controller can become disconnected. The arm and claw can slam into the front of the robot at speed, which can result in damage. The claw is too high off the surface to pick up flat bean bags. If a bean bag is lifted beyond 0 degrees, the robot tips over onto its back. The link between the controller and cortex uses a wire. Whilst driving around, the robot can become stuck on bean bags that are in its path.

Redeveloping a product Developing your robot – What options do you have? It is very easy to “design out” the faults a clawbot has. Task: Open up your Engineering notebook and draw the clawbot as accurately as you can on 1 page of A4. Once you have done this, propose changes to the Clawbot that would require no new parts (i.e. you redesign it using the parts you already have in your kit or that are already on the robot)

Redeveloping a product Solutions – Over engineered but with exceptional control (lots of new parts used here) This clawbot development has been built with a focus on the challenge of picking up the bean bags and scoring them into high goals. It does this be changing the current claw and arm, which could only move up and down in one axis of motion, with a claw that can rotate through an the X, Y and Z axis of motion. Using a turntable, additional motors, a chain and sprocket set and additional motor controllers and metal, the engineer has provided an “ultimate” solution to placing single bean bags in different goals.

Redeveloping a product Solutions – A simplified improvement with two improved features (very few new parts introduced here) This clawbot development has been built to solve three of the key issues with the original clawbot. It also does this without requiring extensive new parts or motors. The first change is to build a frame around the clawbot arm and move its position to the middle of the base of the robot. This improves its centre of gravity and ensures it won’t fall over. The second change is to extend the clawbot arm using longer metal, so meet a higher goal. The third change is to introduce two sensors, one to the arm to stop it going too far back, and one to the front of the base to stop if colliding with its own base.

Redeveloping a product Apply your developments to your Clawbot – Build it better Using just the parts in your kit, your task is to try to improve the design of your robot. Task: Take apart the parts of your robot that you feel need improving, and as a team rebuild your robot to solve those problems. You are not allowed to use anything other than what was provided in your kit. One quick solution to the issue of collecting bean bags off the surface of a table is to flip the orientation of the claw upside down. This directs the claw to the surface and allows it to pick up bags with ease. This is achieved by loosening the nylon locking nuts and refitting them with the motor facing inwards.

LESSON 3 PLENARY As a class, let us consider the following questions? A. What ways did you test your product for faults? B. If given any materials and parts, how would you change your robot? C. Part of VEX Competition rules are that you can use 24 x 18” of Acrylic as part of your robot. With this in mind, how would you use this material in your robot? D. How can sensors improve a Clawbot?

Summary Today you have:  Learnt about testing and evaluating a product to identify design improvements.  Sketched out design solutions to improve a product.  Modified a product to create a new improved “Version 2”. Learning objective: Analyse a finished product and evaluate its performance during a task. Develop a range of design modifications as sketches. Compare and objectively review modifications before improving a product.