Sensory and Neural Systems Engineering

Welcome to the Hartmann Group website.

This page provides a broad overview of our research goals. For more detailed scientific information, please visit our publications page.

Whiskers and the sense of touch

Our sense of touch is mysterious. It is easy for you to reach into your pocket or purse and — without looking — identify your cellphone, keys, or a coin. Somehow, your brain combines information about your hand movements and the contacts that you make, to enable you to perceive a particular object.

The long term goal of our laboratory is to better understand how movement and touch are combined in the brain to enable perception.

We use rats as a model to study the sense of touch. Rats, however, don't use their "hands" (paws) very much to explore objects. Sometimes they do, but mostly they use their whiskers. If you've ever watched a rat run around, you'll notice that they're constantly touching their noses to objects. If you were able to use a slow-motion video camera to watch the rat, as our laboratory does, what you would see is that the rat is continuously brushing its whiskers against objects very rapidly, between 5 and 25 times a second. This behavior is called "whisking." The rat is touching different objects to figure out their location, size, shape, and texture.

Our laboratory is particuarly interested in the contact patterns that the rat's whiskers make as it explores different objects, and in the mechanics of whisking movements. Some of the projects we work on in our lab are:

• We construct small robots with whiskers and simulations of whisker movements to figure out an object's shape
• We use high-speed video to quantify rat whisking behavior
• We developed a three-dimensional model of the rat whisker array. The model can be used to simulate the head and whisker movements that a rat may use to explore different objects.

Sensory data and the control of locomotion

We have recently become interested in how the nervous system might use sensory data from the feet, knees, and hips to help control walking. We recently published a paper that simulated bipedal walking over rough terrain. The paper demonstrated that actuation based on simple combinations of sensory inputs from the joints can lead to stable walking.

Our work on whiskers is supported primarily by grants from the National Science Foundation. Some of our work on locomotion has been supported by the Office of Naval Research and the Jet Propulsion Laboratory.