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comparison org/movement.org @ 267:d487348c461c

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minor wording fixes to movement.org
author Robert McIntyre <rlm@mit.edu>
date Tue, 14 Feb 2012 04:52:23 -0700
parents 2fdcbe8185b1
children c39b8b29a79e
comparison
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261:2fdcbe8185b1 267:d487348c461c
26 This recruitment stragety allows for percise movements at low 26 This recruitment stragety allows for percise movements at low
27 strength. The collection of all motor neurons that control a muscle is 27 strength. The collection of all motor neurons that control a muscle is
28 called the motor pool. The brain essentially says "activate 30% of the 28 called the motor pool. The brain essentially says "activate 30% of the
29 motor pool" and the spinal cord recruits motor neurons untill 30% are 29 motor pool" and the spinal cord recruits motor neurons untill 30% are
30 activated. Since the distribution of power among motor neurons is 30 activated. Since the distribution of power among motor neurons is
31 unequal and recruitment goes from weakest to strongest, 30% of the 31 unequal and recruitment goes from weakest to strongest, the first 30%
32 motor pool might be 5% of the strength of the muscle. 32 of the motor pool might be 5% of the strength of the muscle.
33 33
34 My simulated muscles follow a similiar design: Each muscle is defined 34 My simulated muscles follow a similiar design: Each muscle is defined
35 by a 1-D array of numbers (the "motor pool"). Each number represents a 35 by a 1-D array of numbers (the "motor pool"). Each entry in the array
36 motor neuron which controlls a number of sarcomeres equal to the 36 represents a motor neuron which controlls a number of sarcomeres equal
37 number. A muscle also has a scalar :strength factor which determines 37 to the value of the entry. A muscle also has a scalar :strength factor
38 the total force the muscle can exert when all motor neurons are 38 which determines the total force the muscle can exert when all motor
39 activated. The effector function for a muscle takes a number to index 39 neurons are activated. The effector function for a muscle takes a
40 into the motor pool, and that number "activates" all the motor neurons 40 number to index into the motor pool, and that number "activates" all
41 whose index is lower or equal to the number. Each motor-neuron will 41 the motor neurons whose index is lower or equal to the number. Each
42 apply force in proportion to its value in the array. Lower values 42 motor-neuron will apply force in proportion to its value in the array.
43 cause less force. The lower values can be put at the "beginning" of 43 Lower values cause less force. The lower values can be put at the
44 the 1-D array to simulate the layout of actual human muscles, which 44 "beginning" of the 1-D array to simulate the layout of actual human
45 are capable of more percise movements when exerting less force. Or, 45 muscles, which are capable of more percise movements when exerting
46 the motor pool can simulate more exoitic recruitment strageties which 46 less force. Or, the motor pool can simulate more exoitic recruitment
47 do not correspond to human muscles. 47 strageties which do not correspond to human muscles.
48 48
49 This 1D array is defined in an image file for ease of 49 This 1D array is defined in an image file for ease of
50 creation/visualization. Here is an example muscle profile image. 50 creation/visualization. Here is an example muscle profile image.
51 51
52 #+caption: A muscle profile image that describes the strengths of each motor neuron in a muscle. White is weakest and dark red is strongest. This particular pattern has weaker motor neurons at the beginning, just like human muscle. 52 #+caption: A muscle profile image that describes the strengths of each motor neuron in a muscle. White is weakest and dark red is strongest. This particular pattern has weaker motor neurons at the beginning, just like human muscle.