Mark A. Minor

Climbing the walls [robots]

Presents two underactuated kinematic designs for miniature climbing robots. They use suction. The underactuation is to save weight.

Simple motion planning strategies for spherobot: a spherical mobile robot

Mobile robots have been traditionally designed with wheels and few have explored designs with spherical exo-skeletons. A spherical mobile robot that offers to have a number of advantages, is proposed in the paper. The success of our design is contingent upon development of control strategies for reconfiguration of the sphere. We address the open-loop control problem and present two strategies for reconfiguration. The first strategy uses spherical triangles to bring the sphere to a desired position with a desired orientation. The second strategy uses a specific kinematic model and generates a trajectory comprising straight lines and circular arc segments. As compared to existing motion planners, our strategies require less computation and provide scope for easy implementation.

Hybrid Force–Velocity Sliding Mode Control of a Prosthetic Hand

Four different methods of hand prosthesis control are developed and examined experimentally. Open-loop control is shown to offer the least sensitivity when manipulating objects. Force feedback substantially improves upon open-loop control. However, it is shown that the inclusion of velocity and/or position feedback in a hybrid force-velocity control scheme can further improve the functionality of hand prostheses. Experimental results indicate that the sliding mode controller with force, position, and velocity feedback is less prone to unwanted force overshoot when initially grasping objects than the other controllers.

An Avian-Inspired Passive Mechanism for Quadrotor Perching

Flying robots capable of perch-and-stare are desirable for reconnaissance missions. Inspired by an adaptation that enables songbirds to sleep in trees without active muscle control, the research presented herein details the design for a passive mechanism that enables a rotorcraft to perch reminiscent of a bird perching on a tree branch. Perching is accomplished through the integration of a compliant, underactuated gripping foot and a collapsing leg mechanism that converts rotorcraft weight into tendon tension in order to passively actuate the foot. Analysis of mechanism behavior is presented, and stability tests were performed to characterize the ability of the system to reject disturbances. The results indicate that it is possible to passively perch a rotorcraft on multiple surfaces and support reasonable environmental disturbances. The analysis in this paper can enable passive perching design optimization in vertical take-off and landing systems.

A simple tractor-trailer backing control law for path following

Backing of a tractor-trailer system is a problem addressed in many literatures. It is usually solved using various nonlinear-based control methods, which are often not easy to implement or tune and do not consider the influence of side-slope. We propose a two-tier controller that is simple and intuitive, which directly controls the curvature of the trailers trajectory. It allows the control input to be more directly related to path specification and handles path curvature discontinuity better. A side-slope compensator is designed upon the simple controller to prevent side-slope from deteriorating tracking performance. Experimental results are provided to illustrate the capability of this new algorithm applied to a full scale autonomous vehicle and trailer system in a real field environment using minimal sensing capability. Performance comparison between the compensated and uncompensated systems is also presented. Results demonstrate good performance on modest side-slope.

Under-Actuated Kinematic Structures for Miniature Climbing Robots

This paper presents two biped designs for miniature climbing robots. The designs use underactuation to satisfy space and weight constraints. In the first design, one actuator provides steering and another two propel the robot in a cartwheel style gait. The cartwheel gait is quite effective but space required for the maneuver precludes certain applications. The limitation is overcome in the second design, which uses under-actuation to provide two different forms of locomotion. It uses a crawling stride in confined environments and a faster pivoting gait in open environments. Such adaptability is achieved without increasing the number of actuators. Both robots have been built and have successfully demonstrated their mobility and maneuverability.

Design, implementation, and evaluation of an under-actuated miniature biped climbing robot

The design, implementation, and evaluation of a miniature biped robot for urban reconnaissance are presented. Design specifications for mobility, space requirement weight, sensing, and control are defined. A revolute hip joint is selected based on its enhanced mobility and capability to function in reasonably confined spaces. Small size dictates minimal weight, which is achieved by an under actuated joint structure, providing steering at only one foot, minimizing sensors, and structural optimization. The smart robotic foot supports the robot on a variety of smooth surfaces and provides feedback when a firm grip is established. Adaptable control strategies and dithering are implemented in lieu of minimal sensors and uncertainty created by backlash, gravity, and compliance in the suction feet. The robot is evaluated while performing tasks on surfaces with a variety of inclinations.

A dexterous manipulator for minimally invasive surgery

Presented here is the design of a mechanism for dexterous placement of an end-effector (forceps, scissors, dissectors) during minimally invasive surgery. The mechanism is best suited to function as a manipulator for a surgical robotics system where motion scaling and filtering of surgeon hand movements could be realized in a fashion to improve ergonomics. End-effector degrees of freedom in the form of actuation, bidirectional 180/spl deg/ articulation, and rotation are provided by a compact multilink structure comprised of gears and gear-links. This structure has been optimized to provide a large dexterous workspace, low backlash, small force magnification, excellent stiffness, load capacity and infinite life durability. These conditions are achieved through selection of link configuration, forceps design, optimal link thicknesses, gear profile design, and high strength steels.

Modeling and control of an under-actuated miniature crawler robot

This paper presents the modeling and control of our second generation prototype miniature crawler robot which was targeted to applications in constrained environments. The mechanical design and the drive mechanism of the robot are first discussed A kinematic model is then derived and the motion planning is analyzed. A description of the Texas Instrument DSP-based embedded controller is presented. Finally, experimental results are presented for evaluation of the robot performance.

Avian-inspired passive perching mechanism for robotic rotorcraft

Flying robots capable of perch-and-stare are desirable for reconnaissance missions. Current solutions for perch-and-stare applications utilize various methods to create an aircraft that can land on a limited set of surfaces that are typically horizontal or vertical planes. This paper presents a bio-inspired concept that allows for passive perching on cylindrical-type surfaces. The prototype provides compliant gripping through the use of an underactuated foot. A mechanism inspired by songbird anatomy is integrated that utilizes rotorcraft weight as a way to passively actuate the foot. Successful perching trials on two rods of differing diameters were performed and are discussed. The purpose of this initial design is to act as a proof of concept for the mechanical action of the mechanism; our results demonstrate that passive perching can be achieved through the integration of underactuated gripping with mechanism-generated mechanical advantage.