Design, modeling and control of a hopping robot

Persistent Passive Hopping and Juggling is Possible Even With Plastic Collisions

“…The reality that the foot mass (sometimes called toe mass) is not zero is included explicitly in the hopping models of Rad, Gregorio, and Buehler (1993), Lapshin (1992) and Wei et al (2000), although none of the controllers discussed in these papers attempted to minimize the energy dissipated by collision (or, almost equivalently, from energy lost in active leg retraction).…”

Design Principles for a Family of Direct-Drive Legged Robots

“…Ignoring the three outliers in the K ts plot, a linear fit over the rest of the data gives K ts = 4.39 r, with a coefficient of determination of 0.895. Using the standard thermal model [7], [27], actuators can incur a core rise of 100 C 3 , and the robot's design is assumed to achieve an optimistic (Table II) actuator mass fraction of 40%. Measuring the length of the first link in units of r (gap radius) to cancel the r in the K ts plot, results in min( v ) = 1 r (7).…”

“…It has long been understood in the legged locomotion design literature that a large fraction of the robot's mass budget should be reserved for actuation [27]. Our desire for DD designs pushes this notion toward its extreme as the robots in this family all have approximately 40% of total mass taken up by the actuators, compared to 24% for the modestly geared MIT Cheetah and approximately 10-15% for more conventional machines (detailed in Table II).…”

Dynamic Locomotion With One, Four and Six-Legged Robots

“…SUBJECT TERMS designs and controllers for stable running with power autonomy based on standard electric actuation, instead of tethered, powerful hydraulic actuation. Our planar ARL Monopod I [8,9] demonstrated that by designing the dynamical system, including the compliance, actuator and transmission models, as well as the operating modes in the design process from the beginning, it was possible to achieve dynamically stable locomotion based on electric motors, despite drastically reduced actuator power and energy densities. ARL Monopod I was able to run at up to 1.2 m/s with a specific resistance of 0.7 based on an average mechanical power of 125 W at 1.2 m/s.…”