Board-new-dat/30-dual-foot-dat/30-dual-foot-dat.md
... ...
@@ -7,3 +7,8 @@
7 7
- [[Motor-reduction-Gear]]
8 8
9 9
- [[code-dat]]
10
+
11
+
12
+- [[Mechanical-Synchronization-dat]]
13
+
14
+- [[belt-dat]]
... ...
\ No newline at end of file
engineering-dat/Mechanical-Synchronization-dat/Mechanical-Synchronization-dat.md
... ...
@@ -0,0 +1,192 @@
1
+
2
+# Mechanical-Synchronization-dat
3
+
4
+
5
+
6
+
7
+
8
+✅ 方案 2：链条连接（⭐⭐⭐⭐）
9
+前轴 ──[链轮]====链条====[链轮]── 后轴
10
+
11
+
12
+适合：
13
+
14
+扭矩大
15
+
16
+越野车
17
+
18
+缺点：
19
+
20
+噪音
21
+
22
+重
23
+
24
+要润滑
25
+
26
+
27
+
28
+
29
+✅ 方案 1：前后轴机械联动（最佳）
30
+
31
+- [[belt-dat]]
32
+
33
+Motor → 前轴 ==== 同步带 / 链条 ==== 后轴
34
+
35
+
36
+✔ 前后绝对同步
37
+✔ 一个电机即可
38
+✔ 不需要编码器
39
+
40
+这是最干净、最可靠的解法。
41
+
42
+四、如果你暂时不能改结构（补救方案）
43
+⚠️ 方案 2：前后轴机械联动 + 保留双电机（次优）
44
+Motor A → 前轴
45
+Motor B → 后轴
46
+前轴 ==== 同步带 ==== 后轴
47
+
48
+
49
+注意事项（很重要）：
50
+
51
+同步带必须 略有弹性
52
+
53
+电机必须 同型号
54
+
55
+PWM 必须完全一致
56
+
57
+不要用硬齿轮
58
+
59
+👉 这是“互相容忍”，不是“真正同步”
60
+
61
+
62
+
63
+## Synchronous Belt Drive / Chain Drive Coupling (⭐⭐⭐⭐⭐)
64
+
65
+This method mechanically links the **front axle and rear axle** so they rotate at exactly the same speed, achieving true synchronization **without encoders or software control**. It is the most reliable solution for **geared DC motors** in small RC cars.
66
+
67
+---
68
+
69
+## 1. Principle of Operation
70
+
71
+The front and rear wheel shafts are rigidly connected using a **timing belt** or **chain**, so that rotation of one shaft forces the other to rotate at the same angular speed.
72
+
73
+Front Axle ──[Pulley/Sprocket]====Belt/Chain====[Pulley/Sprocket]── Rear Axle
74
+
75
+Synchronization is guaranteed by physics rather than electronics.
76
+
77
+---
78
+
79
+## 2. Synchronous Belt Drive (Recommended)
80
+
81
+### 2.1 Description
82
+A toothed timing belt meshes with toothed pulleys on both axles, preventing slip and maintaining a fixed speed ratio (typically 1:1).
83
+
84
+### 2.2 Common Belt Types
85
+| Belt Type | Pitch | Typical Use Case |
86
+|---------|------|------------------|
87
+| GT2 | 2 mm | Lightweight, small robots |
88
+| HTD 3M | 3 mm | RC cars, moderate torque |
89
+| HTD 5M | 5 mm | Larger wheels, higher torque |
90
+
91
+### 2.3 Advantages
92
+- No slip (positive engagement)
93
+- Quiet operation
94
+- Low vibration
95
+- Tolerant to small alignment errors
96
+- Easy DIY implementation
97
+
98
+### 2.4 Disadvantages
99
+- Limited torque compared to chain
100
+- Belt tension must be maintained
101
+
102
+### 2.5 Design Notes
103
+- Belt width: **6–10 mm** for small RC vehicles
104
+- Pulley ratio: **1:1** for synchronization
105
+- Include a **belt tensioner** or slotted mounting holes
106
+
107
+---
108
+
109
+## 3. Chain Drive Coupling
110
+
111
+### 3.1 Description
112
+A metal chain engages with sprockets on both axles, commonly used in high-load or off-road applications.
113
+
114
+### 3.2 Common Chain Types
115
+| Chain Type | Pitch | Typical Use Case |
116
+|----------|------|------------------|
117
+| 25H | 6.35 mm | Small off-road vehicles |
118
+| 06B | 9.525 mm | Heavy-duty DIY builds |
119
+
120
+### 3.3 Advantages
121
+- Very high torque capacity
122
+- Extremely durable
123
+- No elastic deformation
124
+
125
+### 3.4 Disadvantages
126
+- Noisy
127
+- Heavier than belts
128
+- Requires lubrication
129
+- Higher precision required in alignment
130
+
131
+---
132
+
133
+## 4. Structural Requirements (Critical)
134
+
135
+### 4.1 Rigid Axle-to-Wheel Connection
136
+Wheels **must not slip** on the axle.
137
+
138
+Recommended shaft types:
139
+- D-shaft
140
+- Hex shaft
141
+- Keyed shaft
142
+
143
+Avoid:
144
+- Friction-fit wheels
145
+- Soft rubber hubs without locking
146
+
147
+---
148
+
149
+### 4.2 Tensioning Mechanism (Mandatory)
150
+
151
+A belt or chain must always include a way to adjust tension:
152
+- Slotted motor mount
153
+- Idler pulley / idler sprocket
154
+- Eccentric tension wheel
155
+
156
+Without tensioning, wear and temperature changes will cause failure.
157
+
158
+---
159
+
160
+## 5. Motor Configuration Recommendation
161
+
162
+### Best Practice
163
+- **Use a single geared motor** to drive one axle
164
+- Mechanically link the second axle via belt or chain
165
+
166
+Motor → Gearbox → Front Axle ==== Belt/Chain ==== Rear Axle
167
+
168
+### Why Not Two Motors?
169
+- Motors fight each other
170
+- Increased current draw
171
+- Gearbox wear
172
+- Reduced efficiency
173
+
174
+---
175
+
176
+## 6. When to Choose Which
177
+
178
+| Scenario | Recommended Method |
179
+|--------|-------------------|
180
+| Small RC car / indoor | Synchronous belt |
181
+| Outdoor / off-road | Chain drive |
182
+| Quiet operation | Synchronous belt |
183
+| Maximum torque | Chain drive |
184
+
185
+---
186
+
187
+## 7. Summary
188
+
189
+- Mechanical coupling guarantees **perfect synchronization**
190
+- No encoders or control algorithms required
191
+- Synchronous belt drive is the best balance of simplicity, noise, and reliability
192
+- Chain drive is suitable for extreme torque or harsh environments
... ...
\ No newline at end of file
mechanics-dat/mechanical-structure-dat/belt-sys-dat/belt-dat/belt-dat.md
... ...
@@ -1,4 +1,103 @@
1 1
2
+
3
+
2 4
# belt-dat
3 5
4
-GT2_Belt_6mm
... ...
\ No newline at end of file
0
+
1
+## open loop belt
2
+
3
+GT2_Belt_6mm
4
+
5
+
6
+
7
+## 闭环同步带
8
+
9
+
10
+GT2-6-200（2mm pitch，6mm 宽，200mm 周长）
11
+
12
+
13
+
14
+
15
+## 紧张方案
16
+
17
+✅ 方案 2：惰轮张紧（最优雅）
18
+ O ← 惰轮
19
+ / \
20
+==== ====
21
+
22
+
23
+惰轮压在同步带背面
24
+
25
+微调惰轮位置即可张紧
26
+
27
+优点
28
+
29
+中心距可固定
30
+
31
+微调方便
32
+
33
+张力可控
34
+
35
+缺点：
36
+
37
+多一个轮子
38
+
39
+占空间
40
+
41
+
42
+
43
+
44
+Compact closed-loop GT2 timing belt configuration and length calculation.
45
+
46
+## Overview
47
+- Belt type: GT2 (2 mm pitch)
48
+- Belt width: 6 mm
49
+- Pulley teeth (both ends): 20T × 2 (1:1 drive)
50
+- Center distance (C): 149 mm
51
+
52
+## Formulas
53
+- Pulley pitch diameter:
54
+
55
+ D = (T × P) / π
56
+
57
+ where
58
+ - D = pulley pitch diameter (mm)
59
+ - T = number of teeth
60
+ - P = belt pitch (mm)
61
+
62
+- Closed-loop belt length for two equal pulleys (1:1):
63
+
64
+ L = 2C + πD
65
+
66
+ where
67
+ - L = belt pitch-line length (mm)
68
+ - C = center distance between shafts (mm)
69
+
70
+## Example calculation (20T GT2 pulley)
71
+1. Pulley pitch diameter:
72
+
73
+ T = 20 teeth
74
+ P = 2 mm
75
+
76
+ D = (20 × 2) / π ≈ 40 / π ≈ 12.73 mm
77
+
78
+2. Belt length:
79
+
80
+ L = 2 × 149 + π × 12.73
81
+ L ≈ 298 + 40 = 338 mm
82
+
83
+## Recommendation
84
+- Preferred standard belt: **GT2-6-340** (GT2, 6 mm width, 340 mm circumference) — strongly recommended.
85
+- GT2-6-338 is not a standard size and is hard to source.
86
+- Choose the 340 mm belt and use an adjustable tensioning mechanism (tensioner or idler) to take up the ~2 mm difference.
87
+
88
+## Summary (specifications)
89
+- Pitch: GT2 (2 mm)
90
+- Width: 6 mm
91
+- Recommended belt circumference: 340 mm
92
+- Pulleys: 20T × 2 (both ends)
93
+- Center distance: 149 mm
94
+
95
+Notes:
96
+- Using a standard 340 mm belt simplifies sourcing and inventory.
97
+- Use a tensioner to ensure proper belt tension and compensate for the small length difference.
... ...
\ No newline at end of file