Design Critique: Lusmo® Automatic Pet Feeder



The Lusmo® is a pet feeder of Japanese design that automatically dispenses food for small dogs or cats and can be programmed to provide up to three meals per day. Pet owners can adjust the quantity of food dispensed (from 1/16 cup to 1 cup) and the time of each meal. I’ve been using the unit in my home for two months and am very happy with it; it is reliable and beautifully designed. Programming the unit, however, is a complicated process that could easily be improved with the implementation of a few simple changes.

Fig. 1: The Lusmo®
Automatic Pet Feeder
(Model L-AF120R).


Improvement Opportunity 1

All programming tasks are completed by engaging the feeder’s three multi-function programming buttons in a variety of sequences and combinations.

Recommended Design Change 1

Simplify programming tasks by giving each task an independent button with corresponding label.


Fig. 2: Diagram of the feeder’s display panel, which can be found in the feeder’s
instruction manual.

The feeder’s display includes a digital screen and three programming buttons (two are represented by the black triangles to the left of the digital screen; one is represented by the black circle to the right of the digital screen). Each programming button performs a variety of functions, depending on the following:

  1. How long the button is pressed.
  2. At which point in a sequence the button is pressed.
  3. Which button (if any) is pressed in combination with it.

This design minimizes the number of programming buttons required to operate the feeder but greatly complicates the feeder’s system mappings, as there is not a logical one-to-one relationship between action and outcome.


Fig. 3: Instructions for programming feeding times, which can be found in the
feeder’s instruction manual.

The feeder’s complicated system mappings are particularly apparent when programming feed times. In order to set a feed time, the user must complete steps 15 listed in figure 3. This sequence is arbitrary and the labeling on the unit itself does not provide adequate instruction nor direction. Thus, in order to change the feeding time, the user must either,

  1. memorize the sequence (what Norman refers to as “knowledge in the head”), or,
  2. have the instruction manual readily available whenever the feeding times needed to be set or changed (what Norman refers to as “knowledge in the world”).

In this instance, neither option is ideal. Illogical sequences such as this, are first, difficult to remember, and second, difficult to retrieve. Using “knowledge in the world” is a much better solution when approaching arbitrary sequences; however, this type of knowledge is only useful if it is available at the moment the sequence needs to be initiated, which, in this case, would require the user to consult the instruction manual whenever the feeding times needed to be set or changed.

Compounding the aforementioned issues is the fact that the sequence must be done quickly: if ten seconds pass between any of the steps in the sequence, the user must begin the process again.

There is also a much more problematic issue with mapping all of the feeder’s functionality to three multi-function programming buttons: namely, that one of the programming buttons used in a variety of sequences also turns off the feeder. If the programming button that controls the power to the feeder is pressed long enough, at the wrong moment in a sequence, the unit could be turned off. This in turn would leave the pet without food for as long as it would take the user to discover the error.

This outcome is unlikely, but the mere possibility of such a serious mistake occurring indicates that the system design does not properly take into account user error.


Fig. 4: Proposed redesign of programming buttons. The power button is offset from
the other programming buttons and given a unique shape in order to reduce the
likelihood of the feeder being turned off by mistake. 

By reorganizing the display panel to include separate buttons for Power, Setting, Mode, Manual, Forward, Backward, Increase, Decrease, and Enter (and labeling each button accordingly), logical sequences for programming the feeder could be developed and implemented, which would greatly improve the ease in which the feeder could be programmed. The redesign would also greatly reduce the risk of the unit being turned off by mistake.

Improvement Opportunity 2

When programming the amount of food to be dispensed by the feeder, the user must select a code, which corresponds to a particular quantity of food, rather than the quantity itself.

Recommended Design Change 2

Replace the current digital screen, which is only capable of displaying a four-digit alphanumeric string, with another, more robust digital screen that would allow for longer alphanumeric strings. Then, the actual quantity of food to be dispensed could be displayed and selected.


Fig. 5: Instructions for setting the feed amount, which can be found in the
feeder's instruction manual.

The process for programming the amount of food to be dispensed employs the same three multi-functional program buttons as the process for programming the feeding time, so implementing Recommended Design Change 1 would also be beneficial to this process.

What is unique to this process is how the necessary information is displayed on the digital screen. Instead of selecting a particular quantity of food, the user selects an “F” code, which corresponds to an actual quantity of food (see diagram in figure 5). While the pairings of the codes to the food quantities are logical (i.e., larger codes=more food), they still require that the user either,

  1. memorize the code-to-quantity pairings if the user would like to select a specific quantity (“knowledge in the head”), or,
  2. have the instruction manual readily available whenever the feeding quantities needed to be set or changed (“knowledge in the world”).


Fig. 6: Proposed redesign of digital screen. The screen would be capable of
displaying a complete feeding quantity with unit of measurement.

Again, neither of these options is ideal. If the digital screen were capable of simply displaying a few more characters (as seen above), the “F” codes would be unnecessary because the quantity of food to be dispensed could be displayed and selected instead.