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Cordless Powered Screwdriver Brainstorm

This example of situation brainstorming is based on material presented in [UE95].

Consider the problem: Design a cordless powered screwdriver for use in home or small shop environments.

As a result of a situation brainstorming session, a team might end up with a list of statements about the product as shown below.

The SD provides plenty of power to drive screws

  • The SD maintains power for several hours of heavy use
    • How many hours will a user need to use it between recharges?
    • What does “heavy” use mean?
  • The SD can drive screws into hardwood
    • What torque needs to be produced?
    • Is “hardwood” the most difficult material users will use?
  • The SD drives sheet metal screws into metal ductwork
    • Does this include “drilling” holes into the metal? What torques are required for that?

The SD makes it easy to start a screw

  • The SD holds the screw before it is driven
    • What are the directions and magnitudes of forces that could dislodge the screw once held by the SD?
  • The SD can be used to create a pilot hole
    • How are pilot holes different from conventional applications?

The SD works with a variety of screws

  • The SD can turn philips, torx, socket, and hex head screws
    • Are these the only types of screws used in the geography where we expect the SD to be used?
  • The SD can turn many sizes of screws
    • What exactly is the range of sizes?

The SD can access most physical locations

  • The SD can be manoeuvred in tight areas
    • What constitutes a “tight area”? (volumes, dimensions, obstructions, etc)
  • The SD can access screws at the end of deep, narrow holes
    • How deep and how narrow of a hole would our users need to access?

The SD turns screws that are in poor condition

  • The SD can be used to remove grease and dirt from screws
    • What amount of grease & dirt is typically found on screws in the situations we are designing for?
  • The SD allows the user to work with painted screws
    • What specific impediments do painted screws impose?

The SD feels good in the user's hand

  • The SD is comfortable when the user pushes on it
    • How do our users define “comfort”?
    • How are the users' hands and arms aligned when using the SD comfortably?
    • Does duration of use impact comfort?
  • The SD is comfortable when the user resists twisting
    • What torques can the users' arms/hands resist without discomfort/injury?
    • What risks of repetitive strain are there as a result of twisting?
  • The SD is balanced in the user's hand
    • How do our users define “balance”?
  • The SD is equally easy to use in right or left hands
  • The SD weight is just right
    • What exactly is the best weight for the SD according to the users and HF aspects?
  • The SD is warm to touch in cold weather
    • How cold is cold? How warm is warm?
  • The SD remains comfortable when left in the sun
    • What is the rate of heating of an SD left in direct sunlight?

The SD is easy to control while turning screws

  • The user can push easily on the SD
    • What is the user pushing into?
    • How strongly can our users push?
    • What gripping strength do our users have?
    • What influences do posture and screw location have on the pushing force of users?
  • The user can resist easily the SD twisting
    • How does hand size influence the user's ability to grip the SD as it twists?
    • What role can texture and shape play?
  • The SD can be locked “on”
    • What if the user must urgently turn it off?
    • When exactly during a task would the user lock it “on”?
    • Where should the lock actuator be located to facilitate use by our users?
  • The SD speed can be controlled by the user while turning a screw
    • Where should the speed controls be located to facilitate use by a human hand?
    • How will the user know what speed settings are available?
  • The SD remains aligned with the screw head without slipping
    • What are the slipping forces involved? From where do they arise?
    • What forces can the user naturally and simply apply to help maintain alignment?
  • The user can easily see where the screw is
    • How good is the vision of our users?
    • What are the lighting conditions when the SD is used?
  • The SD does not strip screw heads
    • What forces cause screws to become stripped?
  • The SD is easily reversible
    • What natural movements and forces can our users apply to change direction of the SD?

The SD is easy to set up and use

  • The SD is easy to turn on
    • Can it be accidentally turned on? What happens then?
    • What natural movements and forces can our users apply to turn on the SD?
  • The SD prevents inadvertent turning off
    • What actions might a user take that will inadvertently turn the SD off?
  • The maximum torque of the SD can be set by the user
    • What torque is a safe maximum for user users?
    • What is the minimum useful torque?
    • How quickly will torque change?
    • Do our users want to be able to change the torque setting while using the SD? Is that safe?
  • The SD provides ready access to bits or accessories
    • What manual dexterity can we expect our users to have for this operation?
    • Exactly what bits and accessories would our users need?
  • The SD can be attached to the user for temporary storage
    • Where on the human body is it safe and convenient to attach/carry the SD?
    • How shall we prevent the SD from turning on accidentally while “stored” in this way?
    • What other items (clothing, etc.) do our users have that we can leverage as “storage” locations?

The SD power is convenient

  • The SD is easy to recharge
    • Where would our users (want to) recharge the SD?
    • How can it be recharged? Are there any new technologies in this regard?
    • How often are our users willing to recharge the SD?
  • The SD can be used while recharging
    • What technologies are excluded by this?
    • What impediments will our users have to negotiate/endure during use-while-recharging?
  • The SD recharges quickly
    • How quickly do our users expect the SD to recharge?
  • The SD batteries are ready to use when new1)
  • The user can apply torque manually to the SD to drive a screw
    • What answers to all the other questions herein would change if the SD were to be used manually?

The SD lasts a long time

  • The SD tip survives heavy use
    • What do our users consider heavy use?
    • How long exactly do our users expect the SD to last?
    • What are the typical conditions for storage in which our users would store a SD?
  • The SD can be hammered
    • What hammering forces may occur in situations involving our users?
    • Do point / blunt impacts occur in our users situations?
  • The SD can be dropped from a ladder without damage
    • Is cosmetic damage acceptable?
    • How would a user know if the SD were functionally damaged?
    • Does the SD need to be failsafe?

The SD is easy to store

  • The SD fits in a toolbox easily
    • What sizes of toolboxes do our users use?
    • What else is in those toolboxes that might damage or otherwise interact with the SD?
  • The SD can be charged while in storage
    • Where will the SD be stored (where will the toolbox be stored) such that the SD can still be charged during storage?
  • The SD resists corrosion when left outside or in damp places
    • What exactly are the matching conditions to which our users would expose the SD?
    • How does corrosion affect durability and lifetime of the SD?
    • Do all parts of the SD have to be equally corrosion-resistant? Which systems are crucial in this regard?
  • The SD maintains its charge after long periods of storage2)
  • The SD maintains its charge when wet
    • What systems of the SD must be kept dry?

The SD has a pleasant sound when in use

  • What sounds do our users find minimally annoying or even pleasant?
  • What sound levels will our users tolerate?

The SD looks like a professional quality tool

  • Is there an aesthetic for power tools that should be maintained?
  • Can the appearance of the SD be customized by users to make them unique?

The SD is safe

  • The SD can be used on electrical devices
  • The SD does not cut the user's hands

Note that these statements are grouped into two or three levels. The main level identifies key issues, and the second level details out what the team (and presumably the client also) means by the main level issues, and the third level identifies key questions.

This three-level form often occurs naturally. A team member will identify some key factor, say convenience, and the facilitator3) of the brainstorming session will guide a short discussion (say, five minutes) on that one topic. Once the discussion dies down, the facilitator will move on to another topic, usually derived from the previous discussion.


This is not necessarily a good item for the list. It assumes batteries are used; it assumes batteries are included or immediately available with the SD; it references a part of the SD, not the SD as a whole. However, virtually all SDs use batteries, so it could perhaps be argued to be a standard expectation - unless you're trying to be very innovative….
this is not just a function of the batteries. Improperly designed/manufactured leads and wiring can cause the batteries to lose charge even if the batteries themselves are ideal for the device.
See the role of the facilitator for more information
design/cordless_powered_screwdriver_brainstorm.txt · Last modified: 2020.03.12 13:30 (external edit)