Ground reaction forces (GRFs) on individual support vary with posture and motion for bipedal mechanisms or systems due to the redundancy in the system. In digital human modeling, specifically posture prediction, the GRFs are predicted, as they are unknown in a virtual environment. Traditionally, models in which the GRFs are predicted have been presented; however, they are always assumed to be on flat ground. Little work has been done to predict the GRFs on uneven or arbitrary terrain. This paper presents a generic method to calculate the vertical GRFs for given standing postures with uneven terrain. The vertical GRFs are predicted based on the generalized forces (torque in revolute joints; force in prismatic joints) calculated using the recursive Lagrangian formulation and a 3-D zero moment point. Motion capture experiments were used to obtain postures for common standing reaching tasks. Force plates were employed to record GRF information for each task. Experimental postures were reconstructed, and the GRF prediction algorithm was used to predict the associated vertical GRFs for each task. Experimental and predicted vertical GRFs are compared to validate the prediction model. The prediction method proved to be valid, with an overall error of 6%.

This paper presents a novel design and analysis of a hyper-redundant continuous robot (biological continuum style manipulator), actuation system, and control strategy. The robot includes 8 flexible segments, though it can be extended to more segments as necessary. In this study the gravity of the springs is neglected due to the manipulation force is much larger than these gravity forces. This mechanism exhibits a wide range of maneuverability and has a large number of degrees of freedom. Each segment is designed using a novel flexible mechanism based on the loading of a compression spring in both transverse and axial directions and using cable-conduit systems. The forward kinematics of the mechanism is also presented and lends itself well to computer control. It is shown that the solution of the transverse deflection of each segment is obtained in a general form, while the stiffness coefficients are obtained in closed form. A prototype robot segment is experimentally tested, the results are verified. A bench-top actuation system has been developed and a control scheme used in prosthetic hand control has been implemented to control the mechanism