Servo

Abstract: Muscular movements are under the control of a servo similar in many ways to those used in engineering control systems but with a subtlety of design not found in man-made servo mechanisms—including an automatic gain compensation for altered load which must be useful, for example, for adjusting to reduced g on the Moon.

Abstract: A visual feedback control scheme, called image-based visual servo, is proposed for manipulators with cameras on their hands. To accomplish specific tasks in unstructured environments, it is essential to have capabilities of recognizing the object position with respect to the manipulator hand. Using the Jacobian matrix relating the camera motion to the object position change in the acquired image, a state space formulation of a visual feedback system is established. On the basis of the task defined in the image plane, the desired motion of the hand is achieved by time-variant state feedback. The image-based scheme is applied to a task of tracking a moving object by the camera (and the hand). Simulations show that the control scheme is stable even under noisy conditions, while the conventional position-based servo tends to be unstable. Experiments on a PUMA 560 show the validity and the effectiveness of the image-based visual servo. >

Abstract: Many factors such as size, power, and weight constrain the design of modular snake robots. Meeting these constraints requires implementing a complex mechanical and electrical architecture. Here we present our solution, which involves the construction of sixteen aluminum modules and creation of the Super Servo, a modified hobby servo. To create the Super Servo, we have replaced the electronics in a hobby servo, adding such components as sensors to monitor current and temperature, a communications bus, and a programmable microcontroller. Any robust solution must also protect components from hazardous environments such as sand and brush. To resolve this problem we insert the robots into skins that cover their surface. Functions such as climbing the inside and outside of a pipe add a new dimension of interaction. Thus we attach a compliant, high-friction material to every module, which assists in tasks that require gripping. This combination of the mechanical and electrical architectures results in a robust and versatile robot.