AMIGO Base

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* Author: [http://w3.wtb.tue.nl/en/research/research_groups/control_systems_technology/ CST Group, TU/e]
 
* Author: [http://w3.wtb.tue.nl/en/research/research_groups/control_systems_technology/ CST Group, TU/e]
* License: BSD
+
* License: CERN OHL v.1.1
 
* Repository: [https://rop.wtb.tue.nl/svn/rop/AMIGO/Base/ https://rop.wtb.tue.nl/svn/rop/AMIGO/Base/]
 
* Repository: [https://rop.wtb.tue.nl/svn/rop/AMIGO/Base/ https://rop.wtb.tue.nl/svn/rop/AMIGO/Base/]
 
* Software: [[www.ros.org|www.ros.org]] ''(Coming Soon)''
 
* Software: [[www.ros.org|www.ros.org]] ''(Coming Soon)''

Revision as of 18:54, 30 November 2011

Part Links
Author
TU/e
CST Group, TU/e
rop@tue.nl
CAD Files
Inventor
STEP
Electrical Drawings
(Coming Soon)

AMIGO: Head | Arms | Torso | Base


Contents


Part Summary

The base acts as the support structure for AMIGO. It provides space for important hardware for the platform like the PC's, batteries, laser range finder and the wheels.

Overview

Under Construction
Figure 1 shows the CAD model of the fully assembled base.

Figure 1: Assembled base of AMIGO.


Mechanics

Base Plate

Figure 2 shows the base plate of Amigo. It is a milled aluminum part. The main part (1) consists of a bottom plate and raised edges at the perimeter of the plate. The plate has a thickness of 5 mm and the raised edges are 25 mm high. The wheel protectors (2) are bolted to the raised edges. The same holds for the round edge protectors (7). Blocks (3) and (4) are used to clamp the batteries to the base plate. Blocks (3) are part of (1), so they are milled from the same piece of aluminum. Blocks (4) are loose parts, which are bolted to blocks (3). The design of the battery clamps is not completely finished yet. The electronic connector is not in it. The mounting point for this is not designed yet. But it is intended to be equal to the mounting point in the Turtle.


Figure 2: The base plate of Amigo.


A hole (5) is made in the centre of the base plate. This hole provides access to the tooth belt. The hole is covered from the bottom side by a 2 mm aluminum plate that is bolted to the base plate with counter sunk M3 bolts. The array of holes (6) is used for cooling of the PC which is positioned above it. Air can flow through the hole into the PC.


Electronic Components Mounted on the Base Plate

Figure 3 shows the positioning of the electronic components that are mounted on the base plate. More information about the electronic components will be given in the electronics chapter. The components are:
1. The batteries
2. Industrial Beckhoff PCs with its stock mounting plate and a support unit that is used to connect it to the base plate.
3. EtherCAT stacks
4. Amplifier for the lifting mechanism
5. Encoder collection print
6. Fuse print
7. 3 DC/DC power converters
8. Laser Range Finder mounted to a beam via a 5mm thick aluminum plate. The 105mm long beam is bolted to the front edge protector (denoted (7) in figure 2)
9. Main relay


Figure 3: Electronic components that are mounted on the base plate.


Omniwheels

Custom made omniwheels are used for Amigo. An exploded view of the wheel is depicted in figure 4. The wheel has a diameter of 150 mm. Ten small rollers (2) are positioned around its perimeter. Each of these rollers is fitted with seven O-rings. These provide the grip. The O rings vary in diameter. (Inner diameter 24 mm, 23 mm, 21 mm, 18 mm) They all have the same thickness (5 mm). The small rollers are relatively large. This allows higher obstacles to be crossed. The diameter of the wheel gives the platform a ground clearance of approximately 40 mm. Two needle roller bearings (INA HK0609) are placed inside each roller to ensure smooth rolling. The axles of the rollers are clamped between the outer rings (1) and (6) and the inner rings (3) and (5). Countersunk M4 bolts (4) are used to bolt the rings together. Both sets of wheels are aligned on the main hub (1) to which one of the outer rings already is attached. 5 M5 bolts (7) are used to bolt the second set of wheels to the main hub. The blue rings at the outside of the rollers are M6 shims with a thickness of 0.5 mm. All components of the wheel are made of aluminum. Technical drawings of the wheel are also provided.

Figure 4: Exploded view of a omniwheel.


Leg

The U profile (1) has flanges at the upper and lower edge of the front plate. The lower flange connects the front plate to the motor support. The upper flange (2) is used for the connection of the upper half of the frame. The rear end plate (3) is inserted between the side plates of the U profile. This plate forms the vertical back plate and the horizontal top plate of the leg. Flanges with holes (4) are added to the vertical plate. These align with the large holes in the side plates. Rivnuts are inserted in these holes and connect the rear end plate to the side plates. The rivnuts provide the threaded holes required to bolt the leg to the central box. They are countersank in the side plates to create a flat outer surface. The flange at the end of the horizonal top plate (6) is also used for the connection of the upper half of the frame. In the cross section view of figure 5 it can be seen that a plate can be inserted between the U profile’s upper flange (2) and the top plate flange. The holes in both flanges align. Rivnuts are inserted in the holes of the top plate flange. They provide the necessary threaded holes to bolt the inserted plate to the leg. This plate presses on top of the leg. To prevent the top plate from bending, two horizontal flanges (5) are added. These are pop riveted (10) to the side plates. The top of the leg is closed by the connection plate (7). This is pop riveted to the front plate of the U profile and to the top plate. A rear plate (8) closes the box. The connection to the U profile is similar to the connections used in the central box. An internal plate (9) is added to provide extra torsional stiffness to the box. Finally, the motor support is glued between the side plates of the U profile. The sheet metal components of the leg are made of two millimeter aluminum sheets. They can be cut with a laser cutter.


Figure 5: Exploded view (left) and cross section view (right) of the leg.


Figure 6 shows the exploded view of one leg with the position of the omniwheel (1) which is attached to the motor (4). Figure 6 shows the assembled motor with an encoder mounted to the back and a gear head at the front. This assembly is inserted in the motor support (2) It must be possible to remove the motor assembly from the completed robot, if this should be necessary. Therefore, it is axially inserted in the motor support. The support is a milled 6061 aluminum part. The motor clamp (3) is positioned over the motor assembly. Two M5 bolts tighten the clamp to the motor support. The motor assembly is clamped radially at the gear head. Finally an amplifier (5) for the motor is bolted to the rear plate.


Figure 6: Exploded view of the leg with its actuators attached.


Central Box

Electronics

(Coming Soon)

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