Boom Lift Crawler with Abstract Actuator Models and Controller
This example models a boom lift using abstract models of the actuators. The lift has 6 hydraulic actuators in the chassis, 7 hydraulic actuators in the boom plus one other passive hydraulic cylinder. The lift was modeled in CAD, imported into Simscape Multibody. The actuators are modeled using prescribed motion with transfer functions to represent the delay in the hydraulic system.
The model includes a simple control system which restricts some of the movements when the lift is in certain positions. Simulink dashboard blocks permit manual testing of the algorithm
Overview of Actuation Systems
The boom lift crawler consists of a chassis and a boom.
The chassis has:
- Four outriggers to level the lift
- Two tracks so the lift can crawl along the ground
The boom has a number of actuators to position a basket with the operator:
- Turret drive: Orient the boom relative to the chassis
- Lift cylinder: Raise the boom vertically
- Tilt cylinder: Adjust the angle of the telescoping boom
- Master and Slave cylinders: Ensure the basket remains level as the boom tilts
- Extend cylinder: Extend the telescoping boom
- Jib cylinder: raise and lower the basket
- Rotate actuator: Orient the basket relative to the boom
The mechanical model was created in CAD software and imported into Simscape Multibody. It includes many closed-loop linkages and models ground contact for the outriggers and the tracks.
Abstract Actuators System
The actuator models are abstract. The joints in the model move using prescribed motion, and a transfer function models the delay from the hydraulic system. This subsystem converts the on/off signal for the actuators to a position.
A very basic control system checks signals from sensors on the boom lift and determines if the user inputs should be permitted or overridden.
Simulation Results: Full Sequence
The plots below shows the result of a test sequence designed to activate all actuators on the boom lift.
Motion of the outriggers along with applied actuator force.
Motion of the tracks along with applied actuator force.
Motion of the lift, extend, and jib actuators along with applied actuator force.
Motion of the tilt, and basket leveling actuators along with applied actuator force.
Motion of the turret and basket rotation actuators along with applied actuator torques.