143 |
While interrelated, the second problem is more relevant |
While interrelated, the second problem is more relevant |
144 |
to robotics and has therefore been dealt with in that context |
to robotics and has therefore been dealt with in that context |
145 |
due to the popularity of the LEGO Mindstorms. |
due to the popularity of the LEGO Mindstorms. |
146 |
|
See e.g. REF!! |
147 |
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|
148 |
Mechanical looseness is a different matter; it suggests |
Mechanical looseness is a different matter; it suggests |
149 |
the following design rules: |
the following design rules: |
151 |
- No frictionless pins. For controllers, the frictionless pins are next to useless |
- No frictionless pins. For controllers, the frictionless pins are next to useless |
152 |
except in special circumstances due to their looseness. |
except in special circumstances due to their looseness. |
153 |
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|
154 |
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- A high gear ratio at the very beginning of the gearing is vital |
155 |
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to alleviate the looseness in the next gears. |
156 |
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|
157 |
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- Axles used in gears must be attached at several points, far enough |
158 |
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from each other. |
159 |
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|
160 |
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- All joints where there is significant force should be designed |
161 |
|
symmetrically, using e.g. 3-long pins with friction. The symmetry |
162 |
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makes the looseness in one direction much less. (This is similar |
163 |
|
to taking the numerical derivative of a function |
164 |
|
|
165 |
|
.. raw latex |
166 |
|
|
167 |
|
$f(x)$ |
168 |
|
|
169 |
|
at |
170 |
|
|
171 |
|
.. raw latex |
172 |
|
|
173 |
|
$x$ |
174 |
|
|
175 |
|
as |
176 |
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|
177 |
|
.. raw latex |
178 |
|
|
179 |
|
$(f(x+\epsilon/2) - f(x-\epsilon/2)) / \epsilon$ |
180 |
|
|
181 |
|
instead of |
182 |
|
|
183 |
|
.. raw latex |
184 |
|
|
185 |
|
$(f(x+\epsilon) - f(x)) / \epsilon$ |
186 |
|
|
187 |
|
|
188 |
Conclusion |
Conclusion |
189 |
========== |
========== |
190 |
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|