Hexapod Foot Sensor Assembly Guide

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<h1>Hexapod Foot Sensor Assembly Guide</h1>

25

<p><b>By James Frye. Updated February 14, 2008</b></p>

26

<p>This tutorial guides you through building and setting up a Hexapod Foot Sensor using a Force Sensing Resistor (FSR).</p>

27

</div>

28

29

30

31

<h2>Kit Contents & Required Materials</h2>

32

<p>The kit includes two FSRs, hexapod foot caps, rubber bumpers, and hubs. You will need to provide: electrical tape, 24–28 AWG hookup wire, heat shrink, solder, and a nylon wire tie.</p>

33

<p><b>Note:</b> This kit is compatible with the AH3-R and 3DOFA legs (BRU/BLK).</p>

</div>

<div class="asm-step-name">Foot Sensor — Prepare the FSR</div>

</div>

<p>Solder some 24 gauge or lighter wires onto the force sensors as shown. Cover the connections with heat shrink.</p>

45

<p>Note: the wires will need enough slack to not bind the legs while the robot is walking. Be generous with the wire length at first — you can always trim after everything's in place.</p>

</div>

<span>Figure 1.</span>

</div>

</div>

</div>

<div class="asm-step-name">Foot Sensor — Prepare the Leg</div>

</div>

<p>Attach the tubing hub to the tubing using a button head screw as shown.</p>

63

<p>Note: if your hubs include additional 4-40 socket head cap screws, they are not needed in this assembly.</p>

</div>

<span>Figure 2.</span>

</div>

</div>

</div>

<div class="asm-step-name">Foot Sensor — Insulate the Tube</div>

</div>

<p>Cover the side of the tube opposite the screw head with electrical tape. This will prevent the sensor terminals from shorting to the tube.</p>

</div>

<span>Figure 3.</span>

</div>

</div>

</div>

<div class="asm-step-name">Foot Sensor — Expose the Adhesive</div>

</div>

<p>Use an exacto knife to carefully peel away the <b>clear plastic</b> piece covering the black adhesive. <span class="warning">Be very careful — if not done carefully the sensor can be damaged!</span></p>

</div>

<span>Figure 4.</span>

</div>

</div>

</div>

<div class="asm-step-name">Foot Sensor — Attach the Sensor</div>

</div>

<p>Stick the adhesive side of the sensor to the end of the leg as shown, then carefully bend the wires to lay along the leg. <span class="warning">Do not bend the sensor tail too sharply!</span> Secure the sensor tail and wires to the leg with electrical tape.</p>

115

<p>Note: the sensor should be centered on the flat of the aluminum hub.</p>

</div>

<span>Figure 5.</span>

</div>

</div>

</div>

<div class="asm-step-name">Foot Sensor — Attach the Bumper</div>

</div>

<p>Peel an adhesive-coated bumper off of the paper and stick it firmly on the end of the leg as shown.</p>

133

<p>Note: this should be centered precisely on top of the FSR. Clear rubber bumpers are included to make alignment easier.</p>

</div>

<span>Figure 6.</span>

</div>

</div>

</div>

<div class="asm-step-name">Foot Sensor — Install Rubber End Cap</div>

</div>

<p>Attach a nylon wire tie to the wires. Connect an ohm meter to the FSR wires. Gently slide the rubber foot over the sensor and tip of the foot. Push it on until the meter reads some resistance, then carefully work the rubber end cap back in the opposite direction just until the meter reads open.</p>

151

<p>If you are unable to get the meter to read open (infinite resistance), you may need to adjust the wire tie or the bend on the sensor from Step 5. After proper setup, the sensor should read open until it makes contact with the ground.</p>

152

<p>On a moving robot, the rubber end cap holds the sensor in place even with significant lateral loading, and the sensor returns to open even after being under load for a long time.</p>

</div>

<span>Figure 7.</span>

</div>

</div>

</div>

162

163

164

<div class="asm-step-name">Foot Sensor — Wiring & Reference</div>

</div>

<p>The simplest way to use the FSR is with a 10k pull-up resistor. Two wiring setups are shown in Figure 8.</p>

170

<p>Setup "A" produces the response illustrated by the red line in the Sensor Output Chart. Setup "B" produces the response illustrated by the blue line.</p>

</div>

<span>Figure 8.</span>

</div>

</div>

<p><b>Sensor Output Chart.</b> Refer to the chart below for expected pressure vs. voltage values.</p>

</div>

</div>

</div>

</div>

Wiki source code of Hexapod Foot Sensor Assembly Guide

Navigation

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2	<style>
3	.asm { font-family: Verdana, Helvetica, sans-serif; font-size: 14px; max-width: 960px; }
4	.asm-step { background: #fff; border: 1px solid #ddd; border-radius: 8px; margin-bottom: 1.5rem; overflow: hidden; }
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17	h1 { font-size: 18px; margin-bottom: 0.25rem; }
18	</style>
19
20	<div class="asm">
21
22	<!-- Header -->
23	<div style="padding: 0.5rem 0 1rem 0;">
24	<h1>Hexapod Foot Sensor Assembly Guide</h1>
25	<p><b>By James Frye. Updated February 14, 2008</b></p>
26	<p>This tutorial guides you through building and setting up a Hexapod Foot Sensor using a Force Sensing Resistor (FSR).</p>
27	</div>
28
29	<!-- Kit contents -->
30	<div class="asm-info">
31	<h2>Kit Contents & Required Materials</h2>
32	<p>The kit includes two FSRs, hexapod foot caps, rubber bumpers, and hubs. You will need to provide: electrical tape, 24–28 AWG hookup wire, heat shrink, solder, and a nylon wire tie.</p>
33	<p><b>Note:</b> This kit is compatible with the AH3-R and 3DOFA legs (BRU/BLK).</p>
34	</div>
35
36	<!-- Step 1 -->
37	<div class="asm-step">
38	<div class="asm-step-header">
39	<div class="asm-step-name">Foot Sensor — Prepare the FSR</div>
40	<div class="asm-step-num">Step 1 / 8</div>
41	</div>
42	<div class="asm-step-body">
43	<div class="asm-step-text">
44	<p>Solder some 24 gauge or lighter wires onto the force sensors as shown. Cover the connections with heat shrink.</p>
45	<p>Note: the wires will need enough slack to not bind the legs while the robot is walking. Be generous with the wire length at first — you can always trim after everything's in place.</p>
46	</div>
47	<div class="asm-step-figure">
48	<img src="https://wiki.lynxmotion.com/info/wiki/lynxmotion/download/servo-erector-set-robots-kits/ses-v1-robots/ses-v1-3-4-dof-hexapods/hexapod-foot-sensor/WebHome/fsrft01.jpg">
49	<span>Figure 1.</span>
50	</div>
51	</div>
52	</div>
53
54	<!-- Step 2 -->
55	<div class="asm-step">
56	<div class="asm-step-header">
57	<div class="asm-step-name">Foot Sensor — Prepare the Leg</div>
58	<div class="asm-step-num">Step 2 / 8</div>
59	</div>
60	<div class="asm-step-body">
61	<div class="asm-step-text">
62	<p>Attach the tubing hub to the tubing using a button head screw as shown.</p>
63	<p>Note: if your hubs include additional 4-40 socket head cap screws, they are not needed in this assembly.</p>
64	</div>
65	<div class="asm-step-figure">
66	<img src="https://wiki.lynxmotion.com/info/wiki/lynxmotion/download/servo-erector-set-robots-kits/ses-v1-robots/ses-v1-3-4-dof-hexapods/hexapod-foot-sensor/WebHome/fsrft02.jpg">
67	<span>Figure 2.</span>
68	</div>
69	</div>
70	</div>
71
72	<!-- Step 3 -->
73	<div class="asm-step">
74	<div class="asm-step-header">
75	<div class="asm-step-name">Foot Sensor — Insulate the Tube</div>
76	<div class="asm-step-num">Step 3 / 8</div>
77	</div>
78	<div class="asm-step-body">
79	<div class="asm-step-text">
80	<p>Cover the side of the tube opposite the screw head with electrical tape. This will prevent the sensor terminals from shorting to the tube.</p>
81	</div>
82	<div class="asm-step-figure">
83	<img src="https://wiki.lynxmotion.com/info/wiki/lynxmotion/download/servo-erector-set-robots-kits/ses-v1-robots/ses-v1-3-4-dof-hexapods/hexapod-foot-sensor/WebHome/fsrft03.jpg">
84	<span>Figure 3.</span>
85	</div>
86	</div>
87	</div>
88
89	<!-- Step 4 -->
90	<div class="asm-step">
91	<div class="asm-step-header">
92	<div class="asm-step-name">Foot Sensor — Expose the Adhesive</div>
93	<div class="asm-step-num">Step 4 / 8</div>
94	</div>
95	<div class="asm-step-body">
96	<div class="asm-step-text">
97	<p>Use an exacto knife to carefully peel away the <b>clear plastic</b> piece covering the black adhesive. <span class="warning">Be very careful — if not done carefully the sensor can be damaged!</span></p>
98	</div>
99	<div class="asm-step-figure">
100	<img src="https://wiki.lynxmotion.com/info/wiki/lynxmotion/download/servo-erector-set-robots-kits/ses-v1-robots/ses-v1-3-4-dof-hexapods/hexapod-foot-sensor/WebHome/fsrft04.jpg">
101	<span>Figure 4.</span>
102	</div>
103	</div>
104	</div>
105
106	<!-- Step 5 -->
107	<div class="asm-step">
108	<div class="asm-step-header">
109	<div class="asm-step-name">Foot Sensor — Attach the Sensor</div>
110	<div class="asm-step-num">Step 5 / 8</div>
111	</div>
112	<div class="asm-step-body">
113	<div class="asm-step-text">
114	<p>Stick the adhesive side of the sensor to the end of the leg as shown, then carefully bend the wires to lay along the leg. <span class="warning">Do not bend the sensor tail too sharply!</span> Secure the sensor tail and wires to the leg with electrical tape.</p>
115	<p>Note: the sensor should be centered on the flat of the aluminum hub.</p>
116	</div>
117	<div class="asm-step-figure">
118	<img src="https://wiki.lynxmotion.com/info/wiki/lynxmotion/download/servo-erector-set-robots-kits/ses-v1-robots/ses-v1-3-4-dof-hexapods/hexapod-foot-sensor/WebHome/fsrft05.jpg">
119	<span>Figure 5.</span>
120	</div>
121	</div>
122	</div>
123
124	<!-- Step 6 -->
125	<div class="asm-step">
126	<div class="asm-step-header">
127	<div class="asm-step-name">Foot Sensor — Attach the Bumper</div>
128	<div class="asm-step-num">Step 6 / 8</div>
129	</div>
130	<div class="asm-step-body">
131	<div class="asm-step-text">
132	<p>Peel an adhesive-coated bumper off of the paper and stick it firmly on the end of the leg as shown.</p>
133	<p>Note: this should be centered precisely on top of the FSR. Clear rubber bumpers are included to make alignment easier.</p>
134	</div>
135	<div class="asm-step-figure">
136	<img src="https://wiki.lynxmotion.com/info/wiki/lynxmotion/download/servo-erector-set-robots-kits/ses-v1-robots/ses-v1-3-4-dof-hexapods/hexapod-foot-sensor/WebHome/fsrft06.jpg">
137	<span>Figure 6.</span>
138	</div>
139	</div>
140	</div>
141
142	<!-- Step 7 -->
143	<div class="asm-step">
144	<div class="asm-step-header">
145	<div class="asm-step-name">Foot Sensor — Install Rubber End Cap</div>
146	<div class="asm-step-num">Step 7 / 8</div>
147	</div>
148	<div class="asm-step-body">
149	<div class="asm-step-text">
150	<p>Attach a nylon wire tie to the wires. Connect an ohm meter to the FSR wires. Gently slide the rubber foot over the sensor and tip of the foot. Push it on until the meter reads some resistance, then carefully work the rubber end cap back in the opposite direction just until the meter reads open.</p>
151	<p>If you are unable to get the meter to read open (infinite resistance), you may need to adjust the wire tie or the bend on the sensor from Step 5. After proper setup, the sensor should read open until it makes contact with the ground.</p>
152	<p>On a moving robot, the rubber end cap holds the sensor in place even with significant lateral loading, and the sensor returns to open even after being under load for a long time.</p>
153	</div>
154	<div class="asm-step-figure">
155	<img src="https://wiki.lynxmotion.com/info/wiki/lynxmotion/download/servo-erector-set-robots-kits/ses-v1-robots/ses-v1-3-4-dof-hexapods/hexapod-foot-sensor/WebHome/fsrft07.jpg">
156	<span>Figure 7.</span>
157	</div>
158	</div>
159	</div>
160
161	<!-- Step 8 with chart -->
162	<div class="asm-step">
163	<div class="asm-step-header">
164	<div class="asm-step-name">Foot Sensor — Wiring & Reference</div>
165	<div class="asm-step-num">Step 8 / 8</div>
166	</div>
167	<div class="asm-step-body">
168	<div class="asm-step-text">
169	<p>The simplest way to use the FSR is with a 10k pull-up resistor. Two wiring setups are shown in Figure 8.</p>
170	<p>Setup "A" produces the response illustrated by the red line in the Sensor Output Chart. Setup "B" produces the response illustrated by the blue line.</p>
171	</div>
172	<div class="asm-step-figure">
173	<img src="https://wiki.lynxmotion.com/info/wiki/lynxmotion/download/servo-erector-set-robots-kits/ses-v1-robots/ses-v1-3-4-dof-hexapods/hexapod-foot-sensor/WebHome/fsrft08.jpg">
174	<span>Figure 8.</span>
175	</div>
176	</div>
177	<div class="asm-fullwidth">
178	<p><b>Sensor Output Chart.</b> Refer to the chart below for expected pressure vs. voltage values.</p>
179	<div style="text-align:center;">
180	<img src="https://wiki.lynxmotion.com/info/wiki/lynxmotion/download/servo-erector-set-robots-kits/ses-v1-robots/ses-v1-3-4-dof-hexapods/hexapod-foot-sensor/WebHome/hfschart.gif" style="max-width:100%; border:1px solid #ccc; border-radius:4px;">
181	</div>
182	</div>
183	</div>
184
185	</div>
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