Abstract
Internal force is a set of contact forces that does not disturb object equilibrium. The elements of the internal force vector cancel each other and, hence, do not contribute to the resultant (manipulation) force acting on the object. The mathematical independence of the internal and manipulation forces allows for their independent (decoupled) control realized in robotic manipulators. To examine whether in humans internal force is coupled with the manipulation force and what grasping strategy the performers utilize, the subjects (n=6) were instructed to make cyclic arm movements with a customized handle. Six combinations of handle orientation and movement direction were tested. These involved: parallel manipulations (1) VV task (vertical orientation and vertical movement) and (2) HH task (horizontal orientation and horizontal movement); orthogonal manipulations (3) VH task (vertical orientation and horizontal movement) and (4) HV task (horizontal orientation and vertical movement); and diagonal manipulations (5) DV task (diagonal orientation and vertical movement) and (6) DH task (diagonal orientation and horizontal movement). Handle weight (from 3.8 to 13.8 N), and movement frequency (from 1 to 3 Hz) were systematically changed. The analysis was performed at the thumb-virtual finger level (VF, an imaginary finger that produces a wrench equal to the sum of wrenches produced by all the fingers). At this level, the forces of interest could be reduced to the internal force and internal moment. During the parallel manipulations, the internal (grip) force was coupled with the manipulation force (producing object acceleration) and the thumb-VF forces increased or decreased in phase: the thumb and VF worked in synchrony to grasp the object more strongly or more weakly. During the orthogonal manipulations, the thumb-VF forces changed out of phase: the plots of the internal force vs. object acceleration resembled an inverted letter V. The HV task was the only task where the relative phase (coupling) between the normal forces of the thumb and VF depended on oscillation frequency. During the diagonal manipulations, the coupling was different in the DV and DH tasks. A novel observation of substantial internal moments is described: the moments produced by the normal finger forces were counterbalanced by the moments produced by the tangential forces such that the resultant moments were close to zero. Implications of the findings for the notion of grasping synergies are discussed.
Similar content being viewed by others
References
Arbib MA, Iberall T, Lyons D (1985) Coordinated control programs for movements of the hand. Exp Brain Res Suppl 10:111–129
Arimoto S, Tahara K, Yamaguchi M, Nguyen PTA, Han M-Y (2001) Principles of superposition for controlling pinch motions by means of robot fingers with soft tips. Robotica 19:21–28
Batschelet E (1981) Circular statistics in biology. Academic Press, London New York Toronto Sydney San Francisco
Baud-Bovy G, Soechting JF (2001) Two virtual fingers in the control of the tripod grasp. J Neurophysiol 86:604–615
Cutkosky MR (1985) Robotic grasping and fine manipulation. Kluwer Academic Publishers, Boston Dordrecht Lancaster
Flanagan J, Johansson RS (2002) Hand movements. In: Ramashandran V (ed) Encyclopedia of the human brain, vol 2. Academic Press, San Deigo, pp 399–414
Flanagan JR, Tresilian JR (1994) Grip-load force coupling: a general control strategy for transporting objects. J Exp Psychol Hum Percept Perform 20:944–957
Flanagan JR, Wing AM (1993) Modulation of grip force with load force during point-to-point arm movements. Exp Brain Res 95:131–143
Flanagan JR, Wing AM (1995) The stability of precision grip forces during cyclic arm movements with a hand-held load. Exp Brain Res 105:455–464
Flanagan JR, Tresilian J, Wing AM (1993) Coupling of grip force and load force during arm movements with grasped objects. Neurosci Lett 152:53–56
Flanagan JR, Wing AM, Allison S, Spenceley A (1995) Effects of surface texture on weight perception when lifting objects with a precision grip. Percept Psychophys 57:282–290
Gao F (2002) Coordination of multi-finger prehension. Unpublished Master Thesis. Department of Kinesiology, The Pennsylvania State University
Gordon AM, Charles J, Duff SV (1999) Fingertip forces during object manipulation in children with hemiplegic cerebral palsy. II: bilateral coordination. Dev Med Child Neurol 41:176–185
Gysin P, Kaminski TR, Gordon AM (2003) Coordination of fingertip forces in object transport during locomotion. Exp Brain Res 149:371–379
Iberall T (1987) The nature of human prehension: three dextrous hands in one. In: IEEE International Conference on Robotics and Automation, vol 4. Raleigh, NC, pp 396–401
Iberall T, Preti M, Zemke R (1989) Task influence on timing and grasp patterns in human prehension. Soc Neurosci Abstr 15:397
Johansson RS (1998) Sensory input and control of grip. Novartis Found Symp 218:45–59
Johansson RS, Westling G (1984) Roles of glabrous skin receptors and sensorimotor memory in automatic control of precision grip when lifting rougher or more slippery objects. Exp Brain Res 56:550–564
Johansson RS, Westling G (1988) Programmed and triggered actions to rapid load changes during precision grip. Exp Brain Res 71:72–86
Kerr J, Roth B (1986) Analysis of multifingered hands. Int J Rob Res 4:3–17
Kinoshita H, Kawai S, Ikuta K, Teraoka T (1996) Individual finger forces acting on a grasped object during shaking actions. Ergonomics 39:243–256
Latash ML, Aruin AS, Shapiro MB (1995) The relation between posture and movement: a study of a simple synergy in a two-joint task. Hum Mov Sci 14:79–107
Mason MT, Salisbury JK (1985) Robot hands and the mechanics of manipulation. MIT Press, Cambridge MA
Murray RM, Li Z, Sastry SS (1994) A mathematical introduction to robotic manipulation. CRC Press, Boca Raton
Nakazawa N, Uekita Y, Inooka H, Ikeura R (1996) Experimental study on human’s grasping force. In: 5th IEEE International Workshop on Robot and Human Communication, pp 280–285
Nakazawa N, Kim I-H, Inooka H, Ikeura R (1999) Force control of a robot hand emulating human’s grasping motion. In: 1999 IEEE International Conference on Systems, Man, and Cybernetics, vol 6. pp 774–779
Proakis JG, Manolakis DG (1996) Digital signal processing: principles, algorithms, and applications. Prentice-Hall, Upper Saddle River New Jersey
Reinkensmeyer DJ, Lum PS, Lehman SL (1992) Human control of a simple two-hand grasp. Biol Cybern 67:553–564
Salisbury JK, Craig JJ (1982) Articulated hands: force control and kinematic issues. Int J Rob Res 1:4–17
Santello M, Soechting JF (2000) Force synergies for multifingered grasping. Exp Brain Res 133:457–467
Scholz JP, Latash ML (1998) A study of a bimanual synergy associated with holding an object. Hum Mov Sci 17:753–779
Serina ER, Mote CD Jr, Rempel D (1997) Force response of the fingertip pulp to repeated compression—effects of loading rate, loading angle and anthropometry. J Biomech 30:1035–1040
Shim JK, Latash ML, Zatsiorsky VM (2003) Prehension synergies: trial-to-trial variability and hierarchical organization of stable performance. Exp Brain Res 152:173–184
Shim JK, Lay BS, Zatsiorsky VM, Latash ML (2004) Age-related changes in finger coordination in static prehension tasks. J Appl Physiol 97:213–224
Smith MA, Soechting JF (2005) Modulation of grasping forces during object transport. J Neurophysiol 93:137–145
Werremeyer MM, Cole KJ (1997) Wrist action affects precision grip force. J Neurophysiol 78:271–280
Wiesendanger M, Serrien DJ (2001) Toward a physiological understanding of human dexterity. News Physiol Sci 16:228–233
Yoshikawa T, Nagai K (1991) Manipulating and grasping forces in manipulation by multifingered robot hands. IEEE Trans Rob Autom 7:67–77
Zatsiorsky V, Latash M (2004) Prehension synergies. Exerc Sport Sci Rev 32:75–80
Zatsiorsky VM, Gregory RW, Latash ML (2002) Force and torque production in static multifinger prehension: biomechanics and control. I. Biomech Biol Cybern 87:50–57
Zatsiorsky VM, Gregory RW, Latash ML (2002) Force and torque production in static multifinger prehension: biomechanics and control. II. Control Biol Cybern 87:40–49
Zatsiorsky V, Gao F, Latash M (2003) Prehension synergies: effects of object geometry and prescribed torques. Exp Brain Res 148:77–87
Zuo B-R, Qian W-H (2000) A general dynamic force distribution algorithm for multifingered grasping. IEEE Trans Syst Man Cybern 30:185–192
Acknowledgements
This study was supported in part by NIH grants AR-048563, AG-018751, and NS-35032. The authors are also thankful to Dr. F. Valero-Cuevas and other participants of the Machines and Organisms Seminar (Cornell University) for useful discussion.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Gao, F., Latash, M.L. & Zatsiorsky, V.M. Internal forces during object manipulation. Exp Brain Res 165, 69–83 (2005). https://doi.org/10.1007/s00221-005-2282-1
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00221-005-2282-1