3.6.1. Permitted load torque estimation

3.6.1. Permitted load torque estimation

 

The load, which will be applied to the mechanical interface of robot's wrist axis, is restricted by allowable weight, allowable load torque and allowable moment of inertia.

 

 Allow payload weight :

 

Table 3‑1 Allow payload weight

Robot model	Allow payload weight
HS165DC	1,619N (165kgf) or less

 

 allowable load torque

 

Table 3‑2 Allowable Load Torque

Robot model	allowable load torque
	J3-axis rotation	J4-axis rotation	J5-axis rotation
HS165DC	980N·m(100kgf·m) or less		490 N·m (50 kgf·m) or less

 

 allowable moment of inertia

 

Table 3‑3 allowable moment of inertia

Robot model	allowable moment of inertia
	J3-axis rotation	J4-axis rotation	J5-axis rotation
HS165DC	64.68kg·m²(6.6kgf·m·s²)		17.64kg·m²(1.8kgf·m·s²)

 

 

Loads must be kept below maximum conditions shown in [Figure 3.6].

 

[Figure 3.6] indicates the range in which the material point can be located when the applied load is at the material point. However, as it is hardly the case where the actual load (end effector) is at the material point, assess by calculating the inertia moment of each axis. To give an example of the applied load is assumed to be at the material point:,

 

(Example) When the robot type is HS165DC, and the weight of the applied load is 165 kg

 

■The allowable center location from the center of the J5 axis

①          The allowable central location in terms of allowable torque

LR1 ≤(allowable torque) / (load weight)

LR1 = 490 Nm / (165 kg ×9.8 m/s2) = 0.30 m

 

②          The allowable central location in terms of allowable inertia moment

LR1 ≤(allowable inertia moment/load weight)1/2

= (17.64 kg·m2/165 kg)1/2 = 0.33 m (> 0.30 m)

 

From the above results, the distance from the center of the J5 axis will be regulated by the allowable torque and be within 0.30 m.

 

■The allowable central location from the center of the J4 axis

 

①          The allowable central location in terms of allowable torque

LB ≤(allowable torque) / (load weight)

LB = 980 Nm / (165 kg ×9.8 m/s2) = 0.61 m

 

②          The allowable central location in terms of allowable inertia moment

LB ≤(allowable inertia moment / load weight)1/2

= (64.68 kg·m2 / 165 kg )1/2 = 0.63 m (> 0.61 m)

 

From the above results, the distance from the center of the J4 axis will be regulated by the allowable torque and be within 0.61 m.

 

n  Torque Map

 

 

Figure 3.6 Wrist Axis Torque Mapping