New to SP, have a question

tspco

I made a wheel, put a motor on it, it spins, perfect.
Now I have the wheel on the SP floor, but the wheel just sits and spins, what do I need to do, in order to make the wheel move along the floor?
Yeah I know pretty basic stuff for some of you, but I installed SP less than 24 hours ago.

DanYHKim

I assume you made a cylinder (to be the wheel) and then put a motor on its center, then joined the motor to the wheel. This will turn the wheel, but the wheel and motor will be stationary.

The motor, and all Sketchyphysics joints, has an 'ignore' characteristic set for them, so they do not physically interact with other solids. An object that is set as 'ignore' will also not move around in the environment, and so the wheel will be fixed to the immobile motor.

To make a motor that can move around, it must be part of a grouped object. I think there are convenient pre-made motor/wheel groups in the Sketchyphysics toolbar, or you can make them yourself. For instance, make a rectangular block using conventional techniques (make rectangle, the push/pull the face to make it 3D). Now anchor a motor to this block, and then select 'all connected' to the block (that is, all faces and edges and also the motor). Make this into a group. This grouped solid will be a regular solid object for Sketchyphysics, and will be subject to gravity, etc including the motor.

Next make a wheel, and position it as appropriate, in line with the motor. Join the wheel to the motor, and then run the simulation. The wheel will turn and drag the block around. It will look stupid because you only have one wheel.

OK, you might be better off searching Youtube for a Sketchyphysics tutorial video.

tspco

Ok I got a car to move along the floor, took some time but I did it!
Now moving on to the next question.
Is there a way to link joints together, for example make a skid steer vehicle, the right motors are linked to each other, and the left motors are linked together, but the two systems are independent, from each other?

DanYHKim

OK. When you make new motors, pistons and other controllable joints, there is a control box that appears with sliders to activate the controls.

If you open the "UI" window from the toolbar button, and then click on a joint, one of the characteristics of the joint is a controller ID. It usually has some name like "slider12244"(slider12244) or something like that.

It turns out that you can assign a name to the slider control by editing this line in the UI window, so it will say: "slider12244"(LeftMotor)

Now, when you run the simulation, the control box will have a slider called LeftMotor, which is much easier to recognize than the random number identifier.

So, if you have two motors on the left side, you can assign them both to the same slider by changing the name inside the brackets. I think you do not want to alter the part of the control name that is outside of the brackets.

Now, your control window will have one slider called LeftMotor that will activate both motors. If you have two motors and give them different acceleration rates, they will speed up in relative proportion to the slider position.

SPECIAL BONUS TIP: Make sure your motors are placed in the same orientation. It is embarrassing to try to impress your friends with your SketchyPhysics simulation, and have your wheels turn in opposite directions.

tspco

Thanks Dan(?)
I figured most of this out on my own. I did also figure out the motor orientation thing, I had motors going opposite way. I watched a few youtubes on SP, some, a few times to make sure I was doing it right.

Now I need to figure out the keyboard control thing, I don't have a joystick...yet, so I need to make lefty, leftx, righty, and the rightx work, for steering and speed, since in the case of a skidsteer machine these things are directly related to each other.
Thanks again!