title: Workspace Shape and Characteristics for Human Two- and Three-Fingered Precision Manipulation.
abstract: OBJECTIVE
  To study precision manipulation, which involves repositioning an object in the fingertips and is used in everyday tasks such as writing and key insertion, and also for domain-specific tasks such as small scalpel cuts, using tweezers, and hand soldering.
  
  
  METHODS
  In this study, the range of positions (workspace) through which 19 participants manipulated a 3.3-4.1 cm-diameter object are measured with a magnetic tracker. Each participant performed two conditions: a two-finger thumb-index finger condition and a three-finger thumb-index-middle finger condition.
  
  
  RESULTS
  The observed workspaces, normalized to a 17.5 cm hand length, are small compared to free-finger trajectories; for the two-finger trials, 68% of points are within 1.05 cm of the centroid and 95% are within 2.31 cm, while the three-finger case shows a narrower distribution, with 68% of points within 0.94 cm of the centroid and 95% of points within 2.19 cm. The longest axis is a long thin arc in the proximal-palmar plane. Analysis of fingertip workspaces shows that the index fingertip workspace volume is the most linear predictor of object workspace (R(2) = 0.98).
  
  
  CONCLUSIONS
  Precision manipulation workspace size and shape is shown, along with how the fingers are used during the manipulation.
  
  
  CONCLUSIONS
  The results have many applications, including normative data for rehabilitation, guidelines for ergonomic device design, and benchmarking prosthetic and robotic hands.
authors.forename: Ian M
authors.initials: IM
authors.lastname: Bullock
authors.forename: Thomas
authors.initials: T
authors.lastname: Feix
authors.forename: Aaron M
authors.initials: AM
authors.lastname: Dollar
mesh_terms: D000293:Adolescent; D000328:Adult; D006804:Ergonomics; D005260:Female; D005385:Fingers / Q000502:physiology*; D018737:Hand Strength / Q000502:physiology*; D006801:Humans; D008297:Male; D013647:Task Performance and Analysis; D055815:Young Adult