I am wondering if there is a way to determine if my machine is in motion? I am looking for the right technology to use to tell when an industrial machine is in motion. I am thinking a sensor linked to an application on a raspberry pie. When I know the machine is moving, I want to output that to other devices (probably using serial/USB) to inhibit the doors from being opened and other safety related tasks.
Any ideas?
Motion of an arm? Or of a vehicle? How does the machine MOVE?
the entire machine moves. It is a 4-wheeled machine.
An accelerometer would detect acceleration, and if it has any electronics at all, you should be able to “tap into” it to send signals to the environment. You’ll really need to provide a lot more details though if you want any meaningful advice.
Thank you Coleman! Here are the details. I have a forklift traveling through the warehouse. The forklift has a data collection terminal mounted to it and for safety reasons, I want to write a program that will blank the screen when it is in motion. We tried an accelerometer and found that once the fork lift reached top speed, the sensor no longer perceived that there was any acceleration (which there was not) and the screen came back on. I don’t know if I am explaining that well but the accelerometer we tried could not differentiate between full speed and stopped. I don’t know if that was a problem with that device or if we chose the wrong base technology. My reading on the subject would indicate the latter.
So, I was thinking a sensiitve gyroscope might be the way to go. No matter how carefully they try to go in a straight line, I think there will always be small changes in the line of travel.
Essentially you want to detect something which is moving at a very steady velocity and almost no vibration. A Gyro measures angular acceleration, so won’t be of much use. You can start withe the least elegant but functional approach of pressing a wheel against one of the driven wheels and using a simple encoder. If the encoder is rotating, that wheel is obviously in motion. One per wheel would be ideal, and you can also mount it perpendicular to the wheel so it’s less visible. Using a spring would ensure contact.
robotshop.com/en/encoder-disks.html
Ex: robotshop.com/en/6mm-rotary- … B-Spa-1042
robotshop.com/en/hubs-couplers.html
robotshop.com/en/robot-wheel.html
A forklift will go from a full stop to a max rate in a few dozen meters. On longer travel distances, they reach max speed well before they reach the next reason to brake. That “fooled” the acceleromter and the screen came back on even though the lift truck was still in motion (at top speed actually which could NOT have been worse). There is also a lot of vibration because these vehicles use hard solid rubber tires and no suspension. Every bump, expansion joint, or piece of pallet on the floor is a fairly big shock to the frame of the forklift.
The “play” in the in the steering linkage means lots of small corrections need to be made nearly continuously; much like when driving a car. these ongoing small corrections should create a never ending stream of changes in angular momentum while the lift truck is in motion. Which, if I understand the gyroscope technology should be enough to keep the screen blank. Especially if we build the software side to wait a second or so before enabling the screen.
What do you think?
If we can make that work, the installation will be trivial. We would need them to mount the box anywhere on the lift truck that was part of the frame. Right on the dashboard would do it. The program on the Raspberry PIe would accept input from the sensor and, when the parameters are met to determine the states of “moving” or “stopped”, we would send the message to the program running on the terminal to be blanked or not.
You can try a low G and low angular rate gyro for more sensitivity. The other approach is to attach a sensor to the “gas” to know when it’s in operation. Just brainstorming at this point.
does Lynxmotion offer a gyroscope with the properties you mention?
Accelerometers: robotshop.com/en/sensors-accelerometers.html
Gyroscopes: robotshop.com/en/sensors-gyroscopes.html
IMUs: robotshop.com/en/sensors-imu.html
RobotShop owns Lynxmotion.
