Robotics Design Process

Jacki Roig

Robotics Design Process Defining the Problem You are confronted with a situation. Here are two examples: A community wants to construct a robot zoo in which the “animals” move their heads, open their mouths and make appropriate sounds when they sense that someone is coming towards them. Design and build […]

Robotics
Design Process

Defining
the Problem


You are confronted with a situation. Here are two examples:

A
community wants to construct a robot zoo in which the “animals”
move their heads, open their mouths and make appropriate sounds when they
sense that someone is coming towards them. Design and build a prototype
device which could satisfy this need.


A local pet shop wishes to sell a range of devices which automatically feed
small cage pets (such as rabbits, gerbils, mice etc.) when their owners
are away for the weekend. Design and build a prototype device which could
satisfy this need.


You need to determine what problem you are trying to solve before you attempt
to design and build a robot to solve a problem. Take the time to study a
number of different situations and once you have decided what the situation
is and you understand exactly what the problem is then write a design brief
in a log book (this will be your working document as you work on your robot.
This log book can be a paper notebook or an electronic document.) This is
a short statement which explains the problem that is to be solved.

Researching
and Designing

  • gathering
    information

  • identifying
    specific details of the design which must be satisfied

  • identifying
    possible and alternative design solutions

  • planning
    and designing a appropriate structure which includes drawings

Having
written a brief, you are now ready to gather information which will help
you to produce a successful design. First you will need to decide what information
you require. This will be different from project to project and will also
depend on the amount of information and knowledge you already have. A useful
step will be to use the following chart. Ask the five questions, then read
the column headed Gathering Information. This will help you plan
the type of information you will need to gather.

Gathering
Information

1.
What is the practical function of the design? (What must my robot do?)

A
design’s practical functions can include:

  • movement
    How will the robot move within its environment? If it were put in
    a different environment, would it still be able to move within this
    new space?
  • manipulation
    How will the robot move or manipulate other objects within its environment?
    Can a single robot move or manipulate more than one kind of object?
  • energy
    How is the robot powered? Can it have more than one energy source?
  • intelligence
    How does the robot “think?” What does it mean to say that
    a robot “thinks?”
  • sensing
    How will my robot “know” or figure out what’s in its environment?
    If it were put in a different environment, would it be able to figure
    out this new environment
2.
What part does appearance (shape and form, surface texture, colour,
etc.) play in the design’s function? What does the robot look like?
Is there a reason for it to look as it does?

Shape
and form are important to a design’s aesthetic qualities, ergonomics,
strength, stability, rigidity, safety

Surface
texture, finish and colour can be appropriate to a design’s:aesthetic
qualities, mechanical, optical and thermal properties, durability,
etc.

3.
What materials are suitable for the design?

The
properties of a material will determine its suitability for a design.
For our work with robotics we have chosen to work with LegoT™.
However, there are many different types of materials that can be and
are used in the construction of robots.

  • strength,
    hardness, toughness, density
  • durability
  • and
    the aesthetic qualities determined by colour, surface texture, pattern,
    etc.

The
materials cost and availability are also important factors.

4.
What construction methods are appropriate to the design?

Construction
techniques fall into the categories of:

  • cutting
    and shaping
  • fabrication
    – the assembly of the parts using screws, bolts, glues, solder,
    etc
  • moulding
    – by the application of a force on the material
  • casting
    – using a mould to form the shape of a solidifying material

A
particular material can only be worked in a limited number of ways.
The method of construction therefore will be determined by the chosen
material, the availability of manufacturing facilities, the skills
of the work force and the production costs.

5.
What are the likely social and environmental effects of the design?
The
manufacture, use and disposal of any product will have both beneficial
and detrimental effects upon people, wildlife and the environment. The
designer therefore, has an enormous responsibility to consider very
carefully the potential effects of any new design. This will include:
health and safety factors, noise, smell, pollution, etc.

Gathering
information can involve reading, listening, conducting interviews and observing.

A
specification is a detailed description of the problem to be solved. It
should ‘spell out’ exactly what the design must achieve.

Creating
a Prototype

You
should ideally think of at least three different ways to solve the problem
before you concentrate on any one in particular. Sketches and notes are
required at this stage. You can also create prototypes using lego for this
step. Once you have created a lego prototype, take a digital picture of
it. Print out the picture and jot your notes below the picture in your log
book. Once you have settled on one solution, go back over the list of specifications
you have made. Make sure that each specification is satisfied.

Now
it the time to produce some working drawings. These are the drawings that
will assist you as you begin constructing the prototype of your structure.
(Here again, lego and a digital camera might be your best friend.) You may
choose to do your drawings by hand or you might want to use a draw program
on the computer to assist you.

Determine
a working schedule for yourself. Draw up a timetable showing how much time
you expect to spend on each part of the design process. Your planning should
also ensure that you have all the necessary materials and equipment that
you need to complete your project.

Programming
and Testing your Robot

Now
it is time to program your robot. This can be achieved in many different
ways. Use can achieve rudimentary intelligence in your robot by using only
relays, potentiometers, bump switches and some discrete components. You
can increase complexity in intelligence in your robot by adding more sensors
and continuing in the same vein of using hardwired logic. By introducing
a more sophisticated control element, the microprocessor, you introduce
a significant new tool in solving the robot control problem. For our robots
we used the RCX Brick that was first developed by Fred Martin at MIT as
the Programmable Brick. See the following two programming examples:

Mindstorms™

Robolab™
has two levels for programming.

Once
you have written your program and downloaded into the RCX brick using the
Infrared Sender, it is time to test your robot to see if it truly does what
you want it to do.

Evaluating
your Robot

As
building and programming work progresses, and the design begins to take
shape, you will automatically carry out tests on the design. You will also
need to complete systems tests at various stages of the construction. If
any of the tests show that you have failure in a joint, or that part of
your structure is not meeting specifications, then you will have to make
modifications in your plan.

When
building and programming is complete, the entire project must be tested
to see if it does the job for which it was designed. An evaluation needs
to then be written. This should be a statement outlining the strengths and
weaknesses in your design. It should describe where you have succeeded and
where you have failed to achieve the aims set out in the specifications.

Here
is a list of questions which will help you to prepare this statement.

  • How
    well does the design function?

  • Does
    the design look good?

  • Is
    the product safe to use?

  • Did
    I plan my work adequately?

  • Did
    I find the construction straightforward or difficult?

  • Were
    the most suitable materials used?

  • Did
    it cost more or less than expected?

  • How
    could I have improved my design?

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