Mechatronics Exercises

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Constant temperature box


We are making a temperature regulated box which is used to survey how different materials feel at different temperatures.


Test procedure:

  • Different boxes are near each other, at different temperatures. They have at least 2 different materials.
  • Hand is inserted to temperature stabilizer, then
  • Two fingers are inserted to box. Touching lasts for 20-30 seconds. New people will not be coming to touch the same box in a short time.
  • Tests are done in a temperature controlled room, movement of the person should be minimized.


  • Our aim is to make 18 test boxes, 9 boxes have tile-samples inside them and other 9 contain wood-samples. In addition one hand-temperature-stabilizer is required.

  • In each group of boxes (2 groups: tile-sample group and wood-sample group), the temperature of the test-samples will be kept in following ranges: 20, 20.5, 21, 21.5, 22, 22.5, 23, 23.5, and 24 Degree C. Hand-stabilizer must be held at constant temperature of 33 degrees.

  • Starting point of temperature range is not fixed, for example 21->25 is also acceptable.
  • The test box should be covered by 5 sides and open only in the front side having enough space to insert two fingers at a time to touch the test-surface during the experiment.

  • The air temperature inside the box can affect experiment; therefore it should be equal to the test-surface-temperature.

  • Thickness of the test-samples used in all boxes should be equal and surface texture should also be maintained uniform.

  • Boxes do not have refrigeration, since room temperature is under target temperatures.

  • Budget is 200-400 euros for each of first 5 protototype boxes.
  • Boxes should have replaceable / changeable samples.
  • Test subject must not see the temperature / material of sample.
  • Boxes should be small enough to be reachable without extra movement.
  • Boxes do not need to be portable.
  • Support for double-blind studies is not required.
  • Relative humidity of the environment does not need to be controlled, but should be equal in all boxes within reasonable accuracy.




Test subject has a plug'n'play -experience. Boxes are at a set temperature, and subject needs only to place fingers in and feel the temperature inside.

Setting and monitoring the temperature of boxes is currently inconvenient. To set the temperature, box has to be reprogrammed with a new target value. In commit this target value can be found at line 920,  

float goalTemperature = 30;

In future, a display and a few buttons will be added for more ergonomical control of device.


Conclusions and Suggestions

The box functions according to the set specifications. This, however, requires a stable environment. In order to make the boxes more independent of external conditions it would need to be insulated. We have now completed two test boxes. The rest of the test boxes will be constructed during the summer along with the stabilizer box. A display which shows the temperature in real time should be included in future boxes. Sometimes there is a need to change the temperature of the box and therefore some kind of switch should be done to avoid unnecessary changes in the code.

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  File Modified
PDF File box.pdf Apr 29, 2015 by Mark Mckay