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The common chimpanzee (Pan troglodytes) is a facultative biped and our closest living relative. As such, the musculoskeletal anatomies of their pelvis and hind limbs have long provided a comparative context for studies of human and fossil hominin locomotion. Yet, how the chimpanzee pelvis and hind limb actually move during bipedal walking is still not well defined. Here, we describe the three-dimensional (3-D) kinematics of the pelvis, hip, knee and ankle during bipedal walking and compare those values to humans walking at the same dimensionless and dimensional velocities. The stride-to-stride and intraspecific variations in 3-D kinematics were calculated using the adjusted coefficient of multiple correlation. Our results indicate that humans walk with a more stable pelvis than chimpanzees, especially in tilt and rotation. Both species exhibit similar magnitudes of pelvis list, but with segment motion that is opposite in phasing. In the hind limb, chimpanzees walk with a more flexed and abducted limb posture, and substantially exceed humans in the magnitude of hip rotation during a stride. The average stride-to-stride variation in joint and segment motion was greater in chimpanzees than humans, while the intraspecific variation was similar on average. These results demonstrate substantial differences between human and chimpanzee bipedal walking, in both the sagittal and non-sagittal planes. These new 3-D kinematic data are fundamental to a comprehensive understanding of the mechanics, energetics and control of chimpanzee bipedalism.

The abnormal aggregation of tau protein into paired helical filaments (PHFs) is one of the hallmarks of Alzheimer’s disease. Although some small molecules capable of inhibiting the aggregation have...

Variability in motor rehabilitation program outcomes can be attributed not only to individual components (human patient/rehabilitation equipment) but also to their system-level interactions. Thus, effective deployment of a rehabilitation program depends upon: 1) suitable therapist selection of user-device ergonomics; 2) adjustable device settings; and 3) exercise regimen parameters; to achieve desired system-level motor performance. In this paper, we discuss aspects of creation of a virtual design environment, leveraging tools from musculoskeletal analysis, optimization, and simulation-based design, to permit therapists to rapidly evaluate and systematically customize rehabilitation programs. Specifically, this framework is intended to facilitate 1) parametric study of ergonomic/device/regimen settings on musculoskeletal performance; 2) use of design tools such as optimization for decision support in arriving at the best program; and 3) scaffolded examination of linkage between form and function by iterative what-if type of analyses. We use two case studies (bicep-curling and motor rehabilitative driving) to highlight benefits of such simulation-based rehabilitation program evaluation.

Cable robots have seen considerable recent interest ensuing from their ability to combine a large workspace with significant payload capacity. However, the cables can apply forces to the end-effector only when they are in tension, and thus form a subclass of control problems requiring unilateral control inputs. Furthermore, actuation redundancy occurs when surplus cables are introduced within the system. On one hand, such redundancy needs to be carefully resolved for accurate tracking of the task. On the other hand, it allows the redistribution of the actuation forces to satisfy some secondary criteria. In this paper, we apply such redundancy for enhanced trajectory tracking by actively controlling the task stiffness of the end-effector. The scheme allow us to specify a lower bound of the task stiffness, which is intended to provide improved trajectory tracking and disturbance rejection performance. Finally, we illustrate the improved control performance within a virtual prototype cosimulation framework.

Doctors, dentists, nurses, athletic trainers, occupational therapists and allied health-care professionals are expected to learn the linkage between anatomy, physiology and ultimately functional-performance of muscles i.e. how muscles affect movement or which sets of muscles carry various loads. However the extent of understanding of functional-performance that can be imparted in a didactic-lecture or cadaver-lab setting of a ldquoGross Anatomyrdquo class is limited. Hence we seek to create the architecture and algorithms for scaffolded interaction with human musculoskeletal simulation models (virtual prototypes) that can make varied ldquowhat-ifrdquo type analyses and hypothesis-testing possible. This is very pertinent in the context of the target audience of healthcare professionals who may lack prior exposure to such virtual computational scenario testing tools. Providing such access is vital to training of the next generation of health care professionals to leverage ubiquitous computing and the quantitative-paradigm.

In this paper, we evaluate the performance of two candidate formulations for distributed motion planning of robot collectives within an Artificial Potential Field (APF) framework. We exploit the parallel between the formulation of motion planning for group of robots coupled by constraints and the forward dynamics simulation of constrained multibody systems to develop the candidate approaches. We compare and contrast these approaches on the basis of ease of formulation, distribution of computation and overall computational accuracy. Traditionally penalty formulations have enjoyed a prominent position in motion planning of robot collectives due to their ease of formulation, decentralization and scalability. However, the instabilities introduced in the form of “formulation stiffness” at the algorithm development stage have the potential to hinder the subsequent control. Representative results from the distributed motion planning for a group of 3 point-mass robots moving in formation to a desired target location are used to highlight the differences.

Rehabilitation is a complex multifaceted process with complexity and variability that depends not only on human patients and/or specialized equipment but also on the nature of their functional interaction. Rapid and effective customization of the functional interactions between the patient and the rehabilitation device thus becomes critical for any rehabilitation program. Two principal dimensions govern the effectiveness of such functional interactions: geometric placement of user-device (ergonomics) and exercise selection and performance (regimen). In this paper, we discuss aspects of creation of a virtual design environment, leveraging tools from musculoskeletal analysis, optimization, and simulation-based design, which will permit a therapist to rapidly evaluate and systematically customize various candidate rehabilitation programs. Specifically, this framework: (i) permits study of parametric performance variability due to ergonomic or regimen variability; and (ii) facilitates use of all design tools such as optimization to determine the best program. We illustrate various aspects of this customization using an illustrative case-study of a motor-rehabilitation haptic virtual driving environment