Terminal guidance of autonomous parafoils is a difficult problem in which wind uncertainty and system underactuation are major challenges. Existing strategies almost exclusively use impact error as the criterion for optimality. Practical airdrop systems, however,must also includeother criteria thatmaybe evenmore important than impact error for somemissions, such as ground speed at impact or con...

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 seco...

This paper considers motion planning for small (e.g. cubesat-type) satellites operating within a few meters of a target object. The main goal is to develop a principled methodology for handling the coupled effects of orbital dynamics, rotational and translational rigid body dynamics, underactuation and control bounds, and other constraints such as obstacles. The proposed approach is based on co...

We present a policy search method that uses iteratively refitted local linear models to optimize trajectory distributions for large, continuous problems. These trajectory distributions can be used within the framework of guided policy search to learn policies with an arbitrary parameterization. Our method fits time-varying linear dynamics models to speed up learning, but does not rely on learni...

An image-based visual servoing (IBVS) method is proposed for controlling the 3D translational motion and the yaw rotation of a quadrotor. The dynamic model of this unmanned aerial vehicle (UAV) is considered at the design stage to account for its underactuation. In contrast with previous IBVS methods for underactuated UAVs, which used spherical image moments as visual features, the proposed con...

This paper presents a control law for the tracking of a cyclic reference trajectory by an under-actuated biped robot. The robot studied is a five-link planar robot. The degree of under-actuation is one during the single support phase. The control law is defined in such a way that only the geometric evolution of the robot is controlled, not the temporal evolution. To achieve this objective, we c...

This paper introduces the iRobot-Harvard-Yale (iHY) Hand, an underactuated hand driven by 5 actuators that is capable of performing a wide range of grasping and in-hand repositioning tasks. This hand was designed to address the need for a durable, inexpensive, moderately dexterous hand suitable for use on mobile robots. The primary focus of this paper will be on the novel simplified design of t...

Millirobots are a promising robotic platform for many applications due to their small size and low manufacturing costs. However, controlling these millirobots is difficult due to their underactuation, power constraints, and size. While hand-engineered controllers can sometimes control these millirobots, they often have difficulties with highly dynamic maneuvers and complex terrains. We present ...

The purpose of this paper is to present a robust tracking control algorithm for underactuated biped robots capable of self-balancing in the presence of external disturbances. The biped is modeled as a five-link planar robot with four actuators located at hip and knee joints. A sliding mode control law has been developed for the biped to follow a human-like gait trajectory while keeping the tors...