A four-DOF planar robotic leg actuated with McKibben artificial muscles was designed, constructed, and controlled. Both position and passive stiffness were independently controllable at each joint. The tunable passive stiffness properties of the actuators provided stable, forward walking for the robot. A benefit of passive joint stiffness is energy efficiency. Results indicate that the leg may be capable of walking on a horizontal plane with its control valves off 90% of the time. The muscle-like properties of these actuators, including high strength-to-weight ratio, tunable passive stiffness, and self-limiting force output, make them well suited for legged robots.

Braided pneumatic actuators exhibit non-linear force-length properties grossly similar to muscle, and have a high strength-to-weight ratio. These properties make them desirable for legged robots. The work emphasizes understanding the actuator properties for later use in simulation and control of legged robots. Static and dynamic mathematical models for the actuators are reported and verified through testing and simulation. In addition, a dynamic air flow model modulated by a solenoid valve was developed to provide modular actuation subroutines for simulation.

This paper describes the kinematic analysis of two different cricket locomotion modalities, and the use of these data in a dynamic simulation to combine and simplify the insect's complex three-dimensional movements. The results of this simulation will then become the input to the design and control of a microrobot capable of mimicking the walking and jumping behaviors of the cricket.

The monopod hopper described fits into a cube that is 5 cm on a side, is autonomous, and is designed to be statically stable and passively dynamically stable. Hopping is achieved through the excitation of a spring-mass system at its resonant frequency. Simulations were extensively used to finalize the design, before construction of the robot. The hopper, although having no active directional control, is able to climb steps up to 1 mm, travel at a rate of 1.5 body lengths per second for an average of over 225 cm before deviating significantly from its original course, and can operate up to 45 min before depleting the energy stored in the batteries.

A rough terrain locomotion controller for an eight-legged demining robot built by K/sup 2/T, Inc. is presented. The method takes inspiration from the behavior of biological organisms to create a robust yet computationally simple controller. Included is a brief description of mechanism based gait control and insect-inspired reflexes for rough terrain locomotion which were previously used to control a hexapod robot with great success. This method is then applied to develop a locomotion controller for the K/sup 2/T crab-like demining robot. In simulation, the resulting controller causes the robot to display successful rough terrain navigation ability including walking over irregular terrain, traversing obstacles on the order of half the tibia length, traversing sparse terrain, and crossing ditches, all without complex sensing or terrain mapping.

Describes the posture controller for a new cockroach-like hexapod robot developed in the Bio-Robotics Laboratory at Case Western Reserve University. The posture controller is based upon the virtual model control scheme and the problem of redundant kinematics is solved using an optimization approach. It does not just control static posture, but is the major component of a future locomotion controller. The robot has complex, animal-like kinematics with 24 degrees of freedom, yet the controller effectively manages its posture despite large perturbations. The algorithm is also computationally efficient.

This paper describes the design and simulation of a cockroach-like hexapod robot which is under construction for the purpose of testing control principles which are being extracted from the cockroach. The cockroach was chosen because of its remarkable running and climbing capabilities and because much is known about its biomechanics and control. The robot is designed with five, four, and three degrees of freedom in the front, middle and rear legs, respectively, to permit it to mimic the different functions of cockroach legs. Pneumatic cylinders actuate each joint and provide opposing muscle-like forces to actuate the joints. Pulse-width modulation controls the actuators with the necessary smoothness and precision. A dynamic simulation has been developed to predict loads on the structure and the required joint torques.