Before I mount all the equipment on a tractor I will mount is on a spare lawn mower that I have so I can get use to all the variables in a safer environment
The actuators that I used before to steer the lawn mower have been removed as they are too slow.
I am replacing the actuators with a very powerful wheel chair motor as i need 75 -100 pounds of thrust to move the stationary wheels. The motor will be attached directly onto the near vertical steering wheel hub. seen as the dark brown/black near vertical rod seen below
the gear on the end go the steering hub mates with a golden moon shaped gear that has 26 teeth.
the question is, as this is an unusual why to control the steering how will I ensure that the motor does not drive into or past the end stops position at tooth position 1 and 26 and damage the wheel chair motor.
Can this be dealt with in the software ie use an encoder to measure the position of the steering hub gear to ensure that it stays with in limits or I could use some contact switch to limit the motors travel.
If this proves too hard then we will go direct to the tractor. However it would be a good use of the otherwise useless lawn tractor.
Can you not set the max steering angle in Steering to limit the travel to a safe range?
Or; use a stronger linear actuator and ensure the geometry is such that it reaches its end stops within the range of the steeling system. It would protect itself then as most have end stop switches.
Gimson robotics have some that do 29mm/sec and 25kg load.
A quick search found some very fast actuators
If you used a feedback actuator you wouldn’t need a WAS either.
I want to get rid of the actuators as they are slow. Mine did 6 inches in 6 seconds that seems about the same as yours. 3 cm/sec almost 1"/sec. I also need 100 pounds of thrust as the lawn mower does not have hydraulics. So when the mower is stationary I need a lot of torque to start moving the wheels on concrete
yes using a WAS and limiting the steering angle would be a simple way to go. As I have not really used the software much I am not sure what it can do. I do not want to go too far down a route to find my ideas will not work with the current code. I guess that’s why I ask a few too many question. In any case the people on this site seem really helpful and I certainly do appreciate your and their answers/help. It will be returned when I get a chance.
I did not respond to your Ardusimple power question as I did not want to be the one that was responsible for any blue smoke.
Max
The max steering angle definitely works fine. I had my sensor bracket break due to clearance issues and it then tried to go way beyond full lock. With that in mind, if you do rely on WAS for limiting, it might be worth fitting two and adding a bit of arduino code to compare them then disable steer if they don’t match.
Tomorrow all being well I intend to buy a linear position sensor to be the WAS.
I looked at the STEER tab on Autosteer. Assuming any WAS will put out from 0 volts to vcc ie 5 volts and if the Max Steer Angle in Degrees is 40 then we would have 8 degrees per volt.
The Steer tab on my pc is set up with " 8 counts per degree" or should that be 8 degrees per volt.
Counts sounds like an encoder not a potentiometer
Am I confused. Normally am
i will try to find the video on this. I think I watch one on this some time ago
OK I am back on the linear actuator solution for steering (temporarily) until I fully understand the working of the code and can get it working predictably with my Mower hardeware.
The reason for this is the motor that I will eventually use for the project is very powerful and I do not want to be using this and learning at the same time as one mistake and some part of the steering system will get bent. Also the mower is already set up for an actuator so no mods are required
The actuator I have is a 6inch stroll with feedback version. It has 5 wires. Two for Vcc and GND and 3 for the potentiometer.
You mentioned that if I had a feedback version that I did not need a WAS. So if I put the potentiometer wires of the actuator in the WAS inputs and put the Vcc and GND in the motor driver outputs all the other IBT wiring to the arduino can be kept the same.
Is this correct?
Lastly when I do return to the wheel chair brushed dc motor can I use micro switched to shut off the power then the steering rack gets need its max position. If so how are the micro switches wired into the PCB2 board.
Then the motor power wires as you would any other motor to the IBT.
If you are using micro switches to prevent damage I would be using them in as fail safe manner as you can. So, NC switches and a relay to allow motor to run.
I got the feedback actuator working with the AOG code in the simulator. nor to tune the simulated system and to fully learn the software and then put it on the mower and try it out for real.
The decide about an alternative it it is not fast enough
thanks for your help…
Personally I would research faster actuators. They make them at least 3 times faster than yours and hugely more powerful (which you could use to combat the speed restriction). To me, the motor idea is asking for disaster and adding complexity.
Researching actuators as we speak. If I can find faster ones then this seems the best way to go. Anyway this was my original solution.
In parallel to working on this Ie actuators I need to find a motor driver (or a way) that can switch between RC control (PWM) of the actuator and the Arduino control (also PWM) by flipping a switch on the RC transmitter.
I have done this before with Sabertooth and Roboteq motor controllers in other projects when PC was with PWM and the Arduino was Serial and flipping between them was done by the transmitter and motor controller
Not currently sure how to do this with the current set up. However I do need to control the lawn mower by RC when not using the AOG to control the steering
Hello max2019,
Did you continue your mower test?
Concerning the detection of the right and left limit switches, I carried out the assembly below:
The angle sensor is realised with a 10 k potentiometer.
