Motorised knob simulator boosts appliance design

Knobs and buttons are everywhere, on TVs, microwave ovens, washing machines, cookers, almost every domestic appliance. It is important from the users’ point of view that these controls are firm and responsive but carrying out tests on different kinds of knobs is hard before marketing a new product. Italian scientists have now developed a knob simulator that tests how easily a particular design is to grip or twist and the response users get when they press the buttons in the right way.

Writing in the International Journal of Advanced Mechatronic Systems, Valentina Colla of the Scuola Superiore Sant’Anna, in Pisa and Benedetto Allotta of the University of Florence, explain how many consumers judge a product by the quality of its knobs and buttons. They point out that while knob assessment is a rather subjective matter most users agree on certain qualities but identifying whether a particular knob fulfils the desires of hundreds if not thousands of users is usually not possible before a product reaches the marketplace.

Nevertheless, say the researchers, “When a customer is choosing a domestic appliance to acquire, one of the most common actions driving the decision process consists in manoeuvring its knobs and buttons.” This rough test does not necessarily reveal overall quality of a product, but inadequate knobs and buttons can easily deter a customer from buying a particular product.

The researchers have developed a mechatronic device that simulates a knob’s behaviour and so could be used to support an extensive campaign of end-users tests. Specifically, the simulator, which they describe as a haptic device, can allow designers to test different hand-grip behaviours with volunteers acting as potential buyers of a given product. The simulator consists of a brushless DC motor that can provide different levels of resistance to rotation, a force sensor, and a bush to which the knob to be tested can be attached. Different cams can be used to simulate different types of knob rotation, smooth, a definite click between positions or a response somewhere between those two.

The team says this successful feasibility could be extended to investigate stick-slip phenomena more deeply and to look at how friction affects knob simulation.

“Passivity control of a haptic device for the simulation of knobs” in Int. J. Advanced Mechatronic Systems, 2011, 3, 304-311

The opposite of built-in obsolescence

Manufacturers should be encouraged to make products that last longer, retain their retail value and are more readily recyclable after use, according to green consultant Peter Lang. Lang is co-founder of the charity Green and Away and a former Adviser to the Green Deputy Mayor of London. Writing in the International Journal of Green Economics, he suggests sustainability will only be achieved by promoting growth in high-quality goods and the phasing out of “shoddy” products.

“Society should be seeking growth in the quality of goods and services,” he says, “This change from quantity to quality is necessary because Western industrialised economies are already consuming beyond the planet’s carrying capacity.”

Lang explains that without changes in taxation and regulation, there will not be a cultural shift towards such high-quality goods that last longer, are more easily repaired and maintain their value on the second-hand market. Eradicating the manufacturing culture that leads to stickers proclaiming “No user serviceable parts” on electrical goods and plastic cases that either have no screws or cannot easily be opened for do-it-yourself repair, under the guise of “health and safety” represents an important part of this. Without this and other changes, we will continue to dispose of electrical goods, furniture, kitchenware, household goods and other products prematurely.

“The suspicion is that manufacturers are confident that their goods will be reliable for a year, but not much longer,” says Lang. “The cost of the product when new seems to make little difference: a £50 video recorder has a one year warranty, as does a £15,000 car,” he adds. “A cynic might be grateful that our planet takes all of 12 months to circle the sun: if it was less then warranties might be shorter too.” Longer warranties and guarantees seem only to apply to things like cutlery, which tend to lack moving parts or any likelihood of falling into disrepair without particularly severe handling and use.

He suggests that changes that are both financially and also culturally attractive will encourage consumers to opt for better-quality products and so nudge the manufacturers to improving their goods. Essential to such endeavours is strengthening existing “fit for purpose” legislation that protects consumers. He believes that products should either be designed “for life” or at the very least come with a label indicating life expectancy so that consumers can make a more informed decision as to which product to buy.

“To some these changes may seem harsh, but the crises of climate change, water and air pollution, and waste from manufacturing are already becoming huge,” says Lang. If we can change the manufacturing and consumer culture to choose high-quality over shoddy, longer lasting and more easily repaired, then we might again achieve a society that appreciates this quality and reduces dramatically our demands on raw materials, energy and waste facilities. Who knows, we might one day see a market in antique kettles and televisions that still function when plugged in!

Peter Lang (2011). Promoting the growth of high quality goods and the phasing out of shoddy products International Journal of Green Economics, 5, 126-132