Robots are fun to play with, but they can be insolent during social interaction with humans if badly programmed, a researcher said on Tuesday.

It is important to program robots to change moods by better understanding and adapting to human behavior, especially as robots play a bigger role in assisted living, said Maja Matarić, founding director of the University of Southern California's Center for Robotics and Embedded Systems, during a speech at the RoboDevelopment conference on Tuesday in Santa Clara, California.

"You can endow a robot with a personality ... but it should not be rude," Matarić said. Unlike some humans, robots are not sociopaths, Matarić said. Robots can stay a distance away and still interact with a person. However, people, especially at-risk patients, need social interaction, so the closer and more mobile a robot, the better.

By taking cues from body movement and health readings gathered from a body, robots can adapt behavior and take better care of patients, Matarić said

USC is experimenting with robots as coaches that direct the exercise and movement of patients suffering from cardiac or mental diseases. With the help of wearable technologies like sensors on humans, robots are able to judge and monitor human behavior and activity, based on which patients are directed to do certain activities.

For example, by collecting information from bracelet sensors on hands, robot coaches are encouraging cardiac patients to exercise. Robots are also helping Parkinson's disease patients move more appropriately by detecting walking movement with the help of a leg band on patients.

Cameras in a robot are another way to detect movement, but sensors are effective for patients concerned about privacy issues, Matarić said. Wearable sensors can also keep track of human health.

Humans need to feel cared for and encouraged to do activities, but for sustained engagement, robots need to understand a patient and adapt to their behavior, Matarić said. By taking real-time cues from health and movement reads, robots are now being programmed to motivate patients and adapt to changing moods and needs.

Robots can talk in engaging tones to motivate patients, but also need to know when to play music or read a book to calm a patient. Cardiac patients can reach high frustration levels, and certain sensors monitoring a patient's heart rate and blood pressure can indicate those levels, based on which a robot can react.

Customizable robots can also detect early signs of dementia or Alzheimer's disease, for which they can provide continued support, Matarić said. Robots detecting sustained wayward movement in a person can identify it as an early sign of dementia.

Close to 1 million residents in the U.S. in assisted living have dementia, and 26 million worldwide have Alzheimer's disease, with the number expected to reach 100 million by 2050, Matarić said.

The assistive robots being developed by USC will be ready for commercial use in a few years; venture capitalists just need to look at the technology and invest in it, Matarić said in an interview after the speech. The need for caretakers is dire -- well-trained workers are few and nursing shortages are already an issue, and robots can fill that role, Matarić said.

A professional company also needs to repackage the robots to make them attractive to consumers. The industry could take off if health insurance companies reimburse patients for charges related to assistive robots, she said.