Have you ever wondered how an AGV-self-weight 3 tons with a 5-ton payload-can precisely start, stop, and cover 8 meters in just 8 seconds? Achieving this feat not only requires powerful drive support but also demands sophisticated control algorithms. Today, we'll break down the technical logic behind this design and show how our YIKONG Smart team has unlocked this project.
1. Design Goals and Basic Parameters
Total Weight: 8 tons (3 tons self-weight + 5 tons payload)
Displacement: 8 meters (from Point A to Point B)
Time Requirement: Complete start-stop within 8 seconds
2. Motion Control Logic: Balancing Speed and Force
2.1 Using a "Uniform Acceleration – Uniform Deceleration" Motion Mode:
First 4 seconds: Accelerate from standstill to the midpoint (4 meters).
Last 4 seconds: Decelerate from the midpoint to the endpoint (remaining 4 meters).
As shown in the diagram, the maximum speed of the AGV is calculated as:
v=2*s/t=2*4/4=2m/s
2.2 Using a "Uniform Acceleration – Constant Speed – Uniform Deceleration" Motion Mode:
Acceleration Phase: Accelerate from standstill to a constant speed.
Constant Speed Phase: Run at a constant speed continuously.
Deceleration Phase: Decelerate from the constant speed back to zero.
From the diagram, the minimum average speed is:
v=s/t,v=8/8=1m/s
Note: If the AGV operates at this minimum average speed, it would cover exactly 8 meters in 8 seconds-leaving no room for acceleration or deceleration. In practice, a typical AGV speed of 1.2 m/s is used for evaluation.
3. Overcoming Two Major Resistances: The "Hurdles" for the AGV
Rolling Friction Resistance (Ground Resistance):
Once the AGV drive wheel is in motion, rolling friction comes into play. It is estimated as:
F=8000*10*0.03=2400N
Inertial Resistance (Resistance during Acceleration/Deceleration):
This is given by:
F=m×aF = m \times aF=m×a
(Calculation to be determined based on the acceleration phase.)
4. Evaluating the AGV's Acceleration Traction Force to Overcome Inertial Resistance
4.1 Evaluation at a Maximum Speed of 2 m/s:
The AGV accelerates linearly from 0 m/s to 2 m/s and decelerates back to 0 m/s, with both acceleration and deceleration phases lasting 4 seconds.
Using the equation s=v0t+0.5at2s = v_0 t + 0.5at^2s=v0t+0.5at2 (with v0=0v_0 = 0v0=0),
we find:a=2*4/4²=0.5m/s²
The traction force required to overcome inertial resistance is then:
F=ma=8000*0.5=4000N
Therefore, the AGV drive wheel must provide a traction force greater than the sum of rolling friction and inertial resistance:
Ftotal>2400+4000=6400 N
4.2 Evaluation at a Maximum Speed of 1.2 m/s:
The AGV accelerates from 0 m/s to 1.2 m/s and decelerates back to 0 m/s, with equal acceleration and deceleration phases.
Let the constant speed phase last xxx seconds. Using the equation s=v0t+0.5at2s = v_0 t + 0.5at^2s=v0t+0.5at2 (with v0=0v_0 = 0v0=0),
we have:a=2*[(8-1.2x)/2]/[(8-x)/2]²=(8-1.2x)/[(8-x)/2]²=4*(8-1.2x)/(8-x)²
Given that the terminal speed during acceleration is 1.2 m/s, the average speed is 0.6 m/s, and the acceleration (or deceleration) time is (8−x)/2(8 - x)/2(8−x)/2, we can also express:
a=0.6/[(8-x)/2]=1.2/(8-x)
Solving these equations yields approximately:
x=56/9≈6.222,a=27/40=0.675
The required traction force to overcome inertial resistance is then:
F=ma=8000*0.675=5400N
Thus, the minimum traction force must satisfy:
Ftotal>2400+5400=7800 N
4.3 For Maximum Speeds between 1.2 m/s and 2 m/s:
You can substitute the specific speed values into the above formulas to calculate the required forces.
5. Fine Control: The Secret to Energy Efficiency and Smooth Operation
The methods above outline a general design approach. With more refined control techniques, acceleration and deceleration phases can be analyzed separately for optimal performance.
For instance, as illustrated, aligning the rolling resistance during deceleration with the reverse traction force can greatly reduce the reverse traction requirement, thereby lowering the maximum required traction force or speed. This enables the AGV drive wheel system to achieve an optimal state that is both energy-efficient and smooth in operation.
6. Summary and Insights
Balance Speed and Traction: Since P=Fv
Critical Matching: The key to proper component selection is the precise matching of the AGV drive wheel diameter with the reduction ratio.
Enhanced Design and Algorithms: An improved vehicle structure and optimized motion control algorithms can further boost operational efficiency and smoothness, achieving energy savings through algorithmic refinement.
Integration of Physics and Control: The design of an AGV is not merely about raw power-it is the perfect blend of physical principles and intelligent motion control algorithms.
Case-Specific Analysis: Each issue must be analyzed in detail based on the specific circumstances; do not simply apply or misinterpret parts of this analysis as a universal solution.
