Knowledge Bank

Force sharing refers to the way that the brain and body parts work together to apply forces to complete tasks. Bimanual force sharing involves using both arms to complete tasks. Force sharing allows humans to complete many daily tasks and requires a good deal of control. Even though force sharing is intuitive for many people, the concepts behind it are still not well understood. The inability to force share can decrease the quality of life since many daily tasks require force sharing and control. The goal of this research was to contribute to the current knowledge of force sharing by simulating a force sharing task between two arms on one able-bodied person. To simulate the force sharing task, two force plates were used. The subject pressed on each plate with one hand with the goal of reaching a desired force. The forces applied to the plates were added together to try to reach the goal force. In each trial, the goal force was varied as well as the fraction contribution of each plate to the force output. By varying both parameters, a range of force sharing tasks was simulated with different levels of task symmetry. We hypothesized that people will produce systematically higher forces for the side that contributes more to the weighted force output. The data suggested that the subjects generally applied more force to the force plate with the greater contribution, but not always. To see if exertion level affected the results, trials with differing goal forces were compared. The data showed that with higher exertion levels, the standard deviation of the force output increased. However, the conclusions from the data cannot be applied to the general population due to the small sample size. Future work could expand the study to more subjects and considering various protocol variants could increase our understanding of force sharing and control.