Mercurial > cortex

comparison org/movement.org @ 306:7e7f8d6d9ec5

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
massive spellchecking
author Robert McIntyre <rlm@mit.edu>
date Sat, 18 Feb 2012 10:59:41 -0700
parents 1eed471e2ebf
children 5d448182c807
comparison
equal deleted inserted replaced
305:19c43ec6958d 306:7e7f8d6d9ec5
7 #+INCLUDE: ../../aurellem/org/level-0.org 7 #+INCLUDE: ../../aurellem/org/level-0.org
8 8
9 9
10 * Muscles 10 * Muscles
11 11
12 Surprisingly enough, terristerial creatures only move by using torque 12 Surprisingly enough, terrestrial creatures only move by using torque
13 applied about their joints. There's not a single straight line of 13 applied about their joints. There's not a single straight line of
14 force in the human body at all! (A straight line of force would 14 force in the human body at all! (A straight line of force would
15 correspond to some sort of jet or rocket propulsion.) 15 correspond to some sort of jet or rocket propulsion.)
16 16
17 In humans, muscles are composed of muscle fibers which can contract to 17 In humans, muscles are composed of muscle fibers which can contract to
18 exert force. The muscle fibers which compose a muscle are partitioned 18 exert force. The muscle fibers which compose a muscle are partitioned
19 into discrete groups which are each controlled by a single alpha motor 19 into discrete groups which are each controlled by a single alpha motor
20 neuton. A single alpha motor neuron might control as little as three 20 neuron. A single alpha motor neuron might control as little as three
21 or as many as one thousand muscle fibers. When the alpha motor neuron 21 or as many as one thousand muscle fibers. When the alpha motor neuron
22 is engaged by the spinal cord, it activates all of the muscle fibers 22 is engaged by the spinal cord, it activates all of the muscle fibers
23 to which it is attached. The spinal cord generally engages the alpha 23 to which it is attached. The spinal cord generally engages the alpha
24 motor neurons which control few muscle fibers before the motor neurons 24 motor neurons which control few muscle fibers before the motor neurons
25 which control many muscle fibers. This recruitment stragety allows 25 which control many muscle fibers. This recruitment strategy allows
26 for percise movements at low strength. The collection of all motor 26 for precise movements at low strength. The collection of all motor
27 neurons that control a muscle is called the motor pool. The brain 27 neurons that control a muscle is called the motor pool. The brain
28 essentially says "activate 30% of the motor pool" and the spinal cord 28 essentially says "activate 30% of the motor pool" and the spinal cord
29 recruits motor neurons untill 30% are activated. Since the 29 recruits motor neurons until 30% are activated. Since the
30 distribution of power among motor neurons is unequal and recruitment 30 distribution of power among motor neurons is unequal and recruitment
31 goes from weakest to strongest, the first 30% of the motor pool might 31 goes from weakest to strongest, the first 30% of the motor pool might
32 be 5% of the strength of the muscle. 32 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 similar design: Each muscle is defined
35 by a 1-D array of numbers (the "motor pool"). Each entry in the array 35 by a 1-D array of numbers (the "motor pool"). Each entry in the array
36 represents a motor neuron which controlls a number of muscle fibers 36 represents a motor neuron which controls a number of muscle fibers
37 equal to the value of the entry. Each muscle has a scalar strength 37 equal to the value of the entry. Each muscle has a scalar strength
38 factor which determines the total force the muscle can exert when all 38 factor which determines the total force the muscle can exert when all
39 motor neurons are activated. The effector function for a muscle takes 39 motor neurons are activated. The effector function for a muscle takes
40 a number to index into the motor pool, and then "activates" all the 40 a number to index into the motor pool, and then "activates" all the
41 motor neurons whose index is lower or equal to the number. Each 41 motor neurons whose index is lower or equal to the number. Each
42 motor-neuron will apply force in proportion to its value in the array. 42 motor-neuron will apply force in proportion to its value in the array.
43 Lower values cause less force. The lower values can be put at the 43 Lower values cause less force. The lower values can be put at the
44 "beginning" of the 1-D array to simulate the layout of actual human 44 "beginning" of the 1-D array to simulate the layout of actual human
45 muscles, which are capable of more percise movements when exerting 45 muscles, which are capable of more precise movements when exerting
46 less force. Or, the motor pool can simulate more exoitic recruitment 46 less force. Or, the motor pool can simulate more exotic recruitment
47 strageties which do not correspond to human muscles. 47 strategies 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.
138 (movement-kernel creature muscle))) 138 (movement-kernel creature muscle)))
139 #+end_src 139 #+end_src
140 140
141 =movement-kernel= creates a function that will move the nearest 141 =movement-kernel= creates a function that will move the nearest
142 physical object to the muscle node. The muscle exerts a rotational 142 physical object to the muscle node. The muscle exerts a rotational
143 force dependant on it's orientation to the object in the blender 143 force dependent on it's orientation to the object in the blender
144 file. The function returned by =movement-kernel= is also a sense 144 file. The function returned by =movement-kernel= is also a sense
145 function: it returns the percent of the total muscle strength that is 145 function: it returns the percent of the total muscle strength that is
146 currently being employed. This is analogous to muscle tension in 146 currently being employed. This is analogous to muscle tension in
147 humans and completes the sense of proprioception begun in the last 147 humans and completes the sense of proprioception begun in the last
148 post. 148 post.
149 149
150 * Visualizing Muscle Tension 150 * Visualizing Muscle Tension
151 Muscle exertion is a percent of a total, so the visulazation is just a 151 Muscle exertion is a percent of a total, so the visualization is just a
152 simple percent bar. 152 simple percent bar.
153 153
154 #+name: visualization 154 #+name: visualization
155 #+begin_src clojure 155 #+begin_src clojure
156 (defn movement-display-kernel 156 (defn movement-display-kernel
238 </video> 238 </video>
239 </center> 239 </center>
240 <p>The worm is now able to move. The bar in the lower right displays 240 <p>The worm is now able to move. The bar in the lower right displays
241 the power output of the muscle . Each jump causes 20 more motor neurons to 241 the power output of the muscle . Each jump causes 20 more motor neurons to
242 be recruited. Notice that the power output increases non-linearly 242 be recruited. Notice that the power output increases non-linearly
243 with motror neuron recruitement, similiar to a human muscle.</p> 243 with motor neuron recruitment, similar to a human muscle.</p>
244 </div> 244 </div>
245 #+end_html 245 #+end_html
246 246
247 ** Making the Worm Muscles Video 247 ** Making the Worm Muscles Video
248 #+name: magick7 248 #+name: magick7