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To address the limited dexterous workspace of the human hand, we have developed the Active Handrest. This device assists in precision manipulation tasks by extending a user’s dexterous workspace while providing ergonomic support for reduced fatigue. People use handrests to complete dexterous activities as routine as providing a signature. However, the dexterous workspace of the statically supported hand is somewhat limited. By providing consistent support over large workspaces the Active Handrest could be useful for performing precision tasks, such as surgery, upper limb rehabilitation, and machining. Our prototype Active Handrest is a planar, human–machine interface that provides support for the user’s wrist and arm while allowing the user to retain complete control over a grasped tool or manipulated device. The Active Handrest uses force input from the user’s hand, position input from a grasped tool, or a combination of these inputs. The device’s controller then converts the input(s) into handrest motions. In this paper we describe our novel device prototype and establish a baseline for its performance. Preliminary experiments were conducted to investigate the effects of control input, velocity limits, and user experience. Subsequent experiments compared the Active Handrest to various other support conditions. Use of the Active Handrest was found to significantly reduce task error and provided better speed-accuracy performance than the other tested support methods.

The Active Handrest is a large workspace assistive robotic device that has been shown to significantly improve the user performance of various movement tasks. This device has the potential to assist highly accurate motions without the need for a robotically enabled or comanipulated tool while allowing the user to retain complete control over a grasped tool. This paper evaluates the Active Handrest's effect on the kinematics of user movements together with various virtual fixture control strategies to further improve the human performance while using the Active Handrest. The most effective fixture strategy for tracing straight lines is first determined. Then, this fixture strategy is directly implemented on the Active Handrest's motions. Finally, the performance of different fixture strategies is assessed through speed-accuracy tradeoff and movement kinematics. It is concluded that fixtures implemented on the Active Handrest are as effective as those implemented on a grasped tool, which enables users of the Active Handrest high accuracy with ordinary tools such as a scalpel or paint brush. The performance is further improved when fixtures are implemented on both the Active Handrest and the grasped tool.

People use handrests every day to complete dexterous activities as routine as providing a signature. However, the dexterous workspace of the hand is somewhat limited. To address this limit, we have developed an Active Handrest to aid in manipulation tasks by extending a user's dexterous work space while providing ergonomic support for reduced fatigue while maintaining or even improving upon the precision obtained from a fixed handrest. Such a device could be useful performing precision tasks over large workspaces surgery, machining, or pick-and-place tasks. prototype Active Handrest is a planar, computer controlled support for the user's wrist and arm that allows control over a grasped tool or manipulation device uses force input from the user's hand, position input from a grasped manipulandum, or a combination of position inputs. The control algorithm of the device then interprets and converts the input(s) into handrest motions. conducted to optimize the control strategy by investigating the effects of control mode and of velocity limits. Task precision and completion time were used as performance metrics showed that the device provided the greatest task its velocity was limited to 5 mm/s, while using control strategy. An experiment was then conducted the Active Handrest to various fixed wrist and arm support conditions, as well as the unsupported condition. Active Handrest was found to reduce task error compared to performing the tasks with an unsupported arm by 26.0% compared to task completion with a static wrist support These results are statistically significant (p < 0.0001). generally completed experiments more slowly using the Active Handrest, performance with the Active Handrest sensitivity of task error relative to task completion experience with our drawing task leads to an increase in accuracy however, the Active Handrest continues to outperform other hand support conditions (p < 0.0001).

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