15 accepted papers
In this work, we build on our method for manipulating unknown objects via contact configuration regulation: the estimation and control of the location, geometry, and mode of all contacts between the robot, object, and environment. We further develop our estimator and controller to enable manipulatio…
We propose a framework for optimizing a planar parallel-jaw gripper for use with multiple objects. While optimizing general-purpose grippers and contact locations for grasps are both well studied, co-optimizing grasps and the gripper geometry to execute them receives less attention. As such, our fra…
We present an approach to robotic manipulation of unknown objects through regulation of the object's contact configuration: the location, geometry, and mode of all contacts between the object, robot, and environment. A contact configu-ration constrains the forces and motions that can be applied to t…
We propose a framework for co-optimizing the shape and motion of rigid robotic effectors for planar tasks. While planning object and robot-object contact trajectories is extensively studied, designing an effector that can execute the planned trajectories receives less attention. As such, our framewo…
A majority of microrobots are constructed using compliant materials that are difficult to model analytically, limiting the utility of traditional model-based controllers. Challenges in data collection on microrobots and large errors between simulated models and real robots make current model-based l…
We present a hybrid differential dynamic programming (DDP) algorithm for closed-loop execution of manipulation primitives with frictional contact switches. Planning and control of these primitives is challenging as they are hybrid, under-actuated, and stochastic. We address this by developing hybrid…
Many insects demonstrate remarkable locomotive capabilities on inclined or even inverted surfaces. Achieving inverted locomotion is a challenge for legged insect-scale robots because repeated attachment and detachment to a surface usually requires the design of special climbing gaits, adhesion mecha
We present the design of an active two-phase finger for mechanically mediated dexterous manipulation. The finger enables re-orientation of a grasped object by using a pneumatic braking mechanism to transition between free-rotating and fixed (i.e., braked) phases. Our design allows controlled high-ba…
Planning locomotion trajectories for legged microrobots is challenging because of their complex morphology, high frequency passive dynamics, and discontinuous contact interactions with their environment. Consequently, such research is often driven by time-consuming experimental methods. As an altern…
We present a power and control autonomous, insect-scale legged robot the Harvard Ambulatory MicroRobot with RF communication (HAMR-F). At only 2.8 g and 4.5 cm in length, HAMR-F is capable of locomotion at speeds up to 17.2 cm/s (3.8 body lengths per second) with an onboard battery. Two microcontrol
This paper develops a custom motion capture system that uses vision-based methods to rapidly and accurately track the body and leg position/orientation of a 1.43g legged microrobot, the Harvard Ambulatory MicroRobot (HAMR). Two new generalized metrics for quantifying locomotion performance are defin…
This paper presents an off-board trajectory controller for a range of stride frequencies (2-45 Hz) that enables zero-radius turns and holonomic control on one of the smallest and fastest legged robots, the Harvard Ambulatory MicroRobot (HAMR). An experimental model is used as the basis for control t…
We present an off-board phase estimator and controller for leg position near the resonance of the Harvard Ambulatory MicroRobot's (HAMR) two degree-of-freedom transmission. This control system is a first step towards leveraging the significant increase in stride length at transmission resonance for…
Full autonomy remains a challenge for miniature robotic platforms due to mass and size requirements of on-board power and control electronics. This paper presents a solution to these challenges with a 2.3g autonomous legged robot. An off-the-shelf optical mouse sensor is adapted for use on the Harva…
This paper presents a non-linear, dynamic model of the flexure-based transmission in the Harvard Ambulatory Microrobot (HAMR). The model is derived from first principles and has led to a more comprehensive understanding of the components in this transmission. In particular, an empirical model of the…