velocity smoother nav2

The two nodes available are: cob_base_velocity_smoother velocity_smoother Hardware Requirements What should happen if the orginal cmd_vel is in the deadband? I know it would be a near total rewrite regardless of what you've done so far, so I just want to bring it up, but it is not a requirement to use it. https://github.com/yujinrobot/yujin_ocs/tree/devel/yocs_velocity_smoother, https://github.com/ipa320/cob_control/tree/kinetic_dev/cob_base_velocity_smoother, https://github.com/kobuki-base/velocity_smoother, https://github.com/kobuki-base/velocity_smoother/blob/devel/src/velocity_smoother.cpp#L161, https://github.com/wilcobonestroo/navigation2/tree/add-velocity-smoother, https://github.com/ros-planning/navigation2/tree/vel_smoother, https://github.com/kobuki-base/velocity_smoother/blob/devel/src/velocity_smoother.cpp#L263-L296, velocity deadband (do not command a velocity between x1 m/s and x2 m/s), Limit to kinematics of the robot platform (accel / decel, velocities, angular/linear), including min deadband, Jerk limitation, though I don't see any examples doing this (?). I will try to finish it this weekend and make a PR. In closed loop mode, it is important that the odometry is high rate and low latency, relative to the smoothing frequency. We don't have access to that information reliably unless we numerically differentiate the odometry which is unstable for closed-loop feedback. Failed to get question list, you can ticket an issue here, a community-maintained index of robotics software There are two primary operation modes: open and closed loop. In CLOSED_LOOP, it will use the odometry from the odom topic to estimate the robots current speed. Feel free to poke me if I can be helpful on the moveit side. I could be wrong, though. By clicking Sign up for GitHub, you agree to our terms of service and Well occasionally send you account related emails. Another question: what is the logical way to have this node running? . This provides a more regular stream of commands to a robot base and interpolates commands between the current velocity and the desired velocity more finely for smoother acceleration / motion profiles. Frequency (Hz) to use the last received velocity command to smooth by velocity, acceleration, and deadband constraints. Also consider the odom_duration to use relative to your odometry publication rate and noise characteristics. Deadband velocities are minimum thresholds, below which we set its value to 0. Moreover, I did not include the deadband yet and I dont know how (or where) to write the documentation. The minimum and maximum velocities for rotation (e.g. Now I feel like a jerk ;) @AndyZe over at PickNik is using Ruckig for MoveIt2, maybe he has some thoughts to share? Non-SPDX License, Build not available. Is this what you also had in mind? I can pick up this issue and work on a nav2 velocity smoother. Package Summary Released Continuous Integration Documented Bound incoming velocity messages according to robot velocity and acceleration limits. https://github.com/yujinrobot/yujin_ocs/tree/devel/yocs_velocity_smoother this is what I've used in previous projects in ROS 1, but not sure if this or another (better) version is available in ROS 2. This will be used to determine the robot's current velocity and therefore achievable velocity targets by the velocity, acceleration, and deadband constraints using live data. In theory you won't have to take 3rd derivatives of noisy mobile base motor data, or am I missing something? What should be the behavior at the top? smoothernavigationrobot node cmd_vel_muxrobotros app. The aim of this package is to implement velocity, acceleration, and deadband smoothing from Nav2 to reduce wear-and-tear on robot motors and hardware controllers by smoothing out the accelerations/jerky movements that might be present with some local trajectory planners' control efforts. Options to look at for porting / listing features to get the best of all worlds. ''' : : ROS QQ: 2642868461 : file content ''' import os from ament_index_python.packages import get_package_share_directory from launch import LaunchDescription from launch.actions import DeclareLaunchArgument from launch.actions import IncludeLaunchDescription from launch . The buffer is an interesting idea. There is another folder called nav2_smoother. Apologies, I will edit to fit the template soon as possible. The diagram below will give you a good first-look at the structure of Nav2. I see that the Kobuko package has 3 options for input: none, odometry and commanded velocities. It's really helped. Would be nice actually to have that abstracted architecturally. we assume the last timestep we met the required state and so we can store the last iteration's velocity/acceleration/jerk to use as the "current" in the next timestep). #2964 is ready for testing if folks want to kick the tires! sphinx.ros indigo Packages. This is signed and thus must be negative to reverse. Since we have a constant stream of these cmd_vel's coming out of the trajectory planner at a relatively consistent rate (and with algorithms that pre-apply varying levels of feasibility constraints) the target setpoint for the velocity is constantly changing but we don't know what the future holds to be able to meaningfully set target acceleration setpoints. The nav2_velocity_smoother is a package containing a lifecycle-component node for smoothing velocities sent by Nav2 to robot controllers. That would make most sense to me. Between me, @AlexeyMerzlyakov and @padhupradheep, you've got resources. The text was updated successfully, but these errors were encountered: Confirming the issue: there is no "ros-humble-nav2-velocity-smoother" found at Jammy on docker, or at ros2 distribution packages list (although nav2_velocity_smoother/ exists in humble branch). privacy statement. Would we rather smoothly and slowly, below the kinematic limits of the robot's acceleration, wait the full 1s to get to the target speed, or get there as quickly as possible and maintain state. Should I put it in its own package or add it to an existing one? Timeout (s) after which the velocity smoother will send a zero-ed out Twist command and stop publishing. See the Navigation Plugin list for a list of the currently known and available smoother plugins. Where loop 2 onwards, we were stuck at commanding a velocity the robot would have never been able to move. Then I can take a look :)! It looks like they all do that in one way or another (timer, while loop, etc). A smoothing module implementing the nav2_behavior_tree::SmoothPath interface is responsible for improving path smoothness and/or quality, typically given an unsmoothed path from the planner module in nav2_planner. I'm not sure the best way off hand to deal with a maximum velocity that is higher than that of the sum of the components. Additionally, the parameters are signed, so it is important to specify maximum deceleration with negative signs to represent deceleration. Also tried apt search ros-humble-nav2 | grep velocity on my host machine with no luck. I don't actually understand the difference between the 2 methods you mentioned, can you elaborate on the second point? My problem is, I have no idea where things go in the Nav2 codebase. The ramp-up and ramp-down seem ok to me. However we want to (1) use the maximum kinematic limits possible to achieve velocities ASAP and maintain them vs using the full time allotted and (2) be able to proportionately bound the velocities of the axes so that we maintain the same (or as similar as possible) commanded direction. Velocity message that arrive are cached and processed at the speed of the internal timer. Code is at: https://github.com/wilcobonestroo/navigation2/tree/add-velocity-smoother, Awesome! But for the first, I don't think generating a trajectory would be any worse than just thresholding. I think its a fabulous idea for us to have a reference on in Nav2. If we're using it for trajectories generated via other methods, then we should have acceleration and other information we can meaningfully use versus live / noisy data. @vinnnyr Can you describe some use cases or scenarios where you use the deadband issue? plotting the cmd_vel shows the linear x jumping between +0.5 and -0.xx. With the idea that these kind of things should be handled by a downstream velocity smoother anyways. That would get around the numerical differentiation of odometry for closed loop feedback, but then would we be unable to support closed loop feedback? It's really similar to Point 1 except you're not using the Ruckig output, you're using the target state that you provided originally. Setting the update rate to higher than the controller rate, so 1 velocity command in = N velocity commands out, somewhat applying a smoothing trajectory since each dt its called will update the velocity towards the commanded velocity by the acceleration profile. The Nav2 smoother is a Task Server in Nav2 that implements the nav2_behavior_tree::SmoothPath interface. I have to remove some buffering code. In the implementation from Care-O-bot (cob) they treat the x and y as independent things to control. I think we can add jerk limits as an option. I'm not sure what (2) entails. Maximum velocities (m/s) in [x, y, theta] axes. Setting the update rate to roughly the same as the trajectory planner rate (thing making, Setting the update rate to higher than the controller rate, so 1 velocity command in =. Our staff is friendly, courteous, and professional. There doesn't seem to be any jerk limitation. See the package's README for more information. I haven't taken a look at this yet, but I did want to point you to ruckig that's being used in #2816. Currently, it is almost following the noisy behavior of the input, because this is within the acceleration limits. I will say though the few examples of 3D velocity smoothers have removed that feature which is telling. The aim of this package is to implement velocity, acceleration, and deadband smoothing from Nav2 to reduce wear-and-tear on robot motors and hardware controllers by smoothing out the accelerations/jerky movements that might be present with some local trajectory planners' control efforts. Also, adding in a "if no command after X time, send 0" in case there's poorly implemented robot base controllers without timeout sequences. It worked reasonably well. Sign in You signed in with another tab or window. We are your 'almost heaven' destination in the foothills of the Rockies, offering rich history, unparalleled outdoor life, memorable dining venues, and an arts community of note.Palmer Lake is one of the best kept secrets of the Colorado Front Range!  however, it does work if we do open loop feedback (e.g. Already on GitHub? If you have high rate odometry, you can use closed-loop mode with a higher smoothing frequency since you'll have more up to date information to smooth based off of. In the other implementations, I also see an approach where the smoother has his own timer (and thus his own publish rate). It should be an almost perfect match, which is why I was confused to see different behavior on our hardware. Merging imminent, thanks @vinnnyr for bringing up this gap. When acceleration limits are set appropriately, this is a good assumption. (1) you can make trajectories that are themselves already jerk limited. I think there's some natural synergies here to use that for this work potentially. See the packages README for more information. Minimum velocities (m/s) to send to the robot hardware controllers, to prevent small commands from damaging hardware controllers if that speed cannot be achieved due to stall torque. Some only handle X, one of the things to make sure is that it supports omni robots in the Y velocity / acceleration direction. Hm , this is a tough issue to generalize. Location: 104 CO-105, Palmer Lake, Colorado 80133. nav2_velocity_smoother sounds good to me! With this minimal configuration, I was able to get the robot rolling around autonomously! Have a question about this project? when both x and y are at their max). rosvelocity smoother. I'll keep this tool in my back pocket though. Topic to find robot odometry, if in CLOSED_LOOP operational mode. --> I'm thinking the latter, which might then argue against using any kind of trajectory libraries, since we would want to use the full limits available to us vs moving below it to use the full time available (is that an option in ruckig? Could someone give me some feedback on this code for this issue? What should happen if the orginal cmd_vel is in the deadband? @wilcobonestroo can you put in a pr? I think it makes sense to add jerk limiting to the trajectory planners perhaps to get around this situation, so that way the computed trajectories generating the commands are limited by it so that the velocity smoother doesn't require to do it -- and then its based on theoretical models and not actual current sensor data so you can differentiate it to your heart's desire. Is jerk limiting important to you? I think for a first-release we can not include jerk, but if @vinnnyr wanted to come in after and include it, that PR would be easily merged. Aren't most of those taking odometry messages https://github.com/kobuki-base/velocity_smoother/blob/devel/src/velocity_smoother.cpp#L161 to check and limit the next velocity command by? After the bulk is in place, adding a couple new parameters and a new constraint would be a trivial PR to review and merge. In my use case, I do not think multiple deadbands would have been needed. Though if we do a trivial v min / max = v0 +/- a * t calculation for thresholding, it's not really taking the current acceleration into account either. Feed the previous Ruckig output state as current state input for the next iteration. That helps understanding the deadband issue So there should probably be several options for the behavior in the band. @vinnnyr how do you feel about jerk ( see last comment), I started to play with this using ruckig just to see how / if it would work. v1 = v0 + a_limits * t) and threshold within limits, but that's not as smooth as generating a trajectory if new discontinuous commands come in. The cob_base_velocity_smoother package provides two implementations for a velocity smoother that both read velocity messages (geometry_msgs::Twist) and then publish messages of the same type for "smoothed" velocity to avoid jerky behavior. The node is designed on a regular timer running at a configurable rate. Traditionally in the ROS navigation ecosystem, we've just taken some $v_i$ and used basic kinematics to find the guard rails of $v_{min}$ and $v_{max}$ based on the set acceleration min/max and threshold it. Updated: Dec 1, 2022 / 08:22 PM MST. Feed the "nominal target state" from the previous iteration as current state input for the next iteration. move_basesmoother. nav2-amcl. The aim of this package is to implement velocity, acceleration, and deadband smoothing from Nav2 to reduce wear-and-tear on robot motors and hardware controllers by smoothing out the accelerations/jerky movements that might be present with some local trajectory planners' control efforts. Nice to know other smart people than me also had to think twice if it was worth going into that level of detail . Maximum acceleration to apply to each axis [x, y, theta]. Sign up for a free GitHub account to open an issue and contact its maintainers and the community. Well another thing to point out is that these all assume independent X, Y, and Theta velocity channels. I don't think that should be the default behavior but I'd be fine with that a parameterized option. motion_velocity_smoother outputs a desired velocity profile on a reference trajectory. In essence, I want the smoother to either command 0.0 or 0.5. Its more about the implementation details that some have bells and whistles others are lacking in. @wilcobonestroo what do you think about that? Thusly, it takes in a command via the cmd_vel topic and produces a smoothed output on smoothed_cmd_vel. Or can we completely drop the jerk issue? what are typical values? . In the three implementations mentioned above I only see speed limits and acceleration limits. Something Yocs does is constraining other channels when one is too high so that the velocity follows the vector previously created, just scaled down https://github.com/kobuki-base/velocity_smoother/blob/devel/src/velocity_smoother.cpp#L263-L296. Implement velocity_smoother with how-to, Q&A, fixes, code snippets. Nav2 uses behavior trees to call modular servers to complete an action. Type of feedback to use for the current state of the robots velocity. Although, for the frequency that the local planners are updated at, this might be overkill, but I think its the most appropriate place for it in the mobile robot stack (which would be relatively analog to MoveIt's use of it as well). Time (s) to buffer odometry commands to estimate the robot speed, if in CLOSED_LOOP operational mode. Already on GitHub? Purpose. Applying kinematic constraints isn't rocket science (see code I linked above) but not sure if there's some additional ideas. It loads a map of potential smoother plugins to do the path smoothing in different user-defined situations. Nothing fancy. By clicking Sign up for GitHub, you agree to our terms of service and In OPEN_LOOP, it will use the last commanded velocity as the next iterations current velocity. ros-humble-nav2-velocity-smoother_1.1.2-1jammy.20221019.170612_amd64.deb: 2022-10-19 17:09 : 122K : ros-humble-nav2-velocity-smoother_1.1.2-1jammy.20221019.171440_arm64.deb: 2022-10-19 17:18 : 113K : ros-humble-nav2-velocity-smoother_1.1.2-1jammy.debian.tar.xz: 2022-08-25 13:24 : 2.0K : ros-humble-nav2-velocity-smoother_1.1.2-1jammy.dsc: 2022 . I think this question is no longer relevant, but indeed I was hoping Jerk could be handled based on cmd_vel alone rather than trying to measure acceleration based off of sensors / localization estimates. Though in doing so, I don't think its reasonable to try to limit jerk if our own inputs and outputs are just Twist and Odometry, we don't have any acceleration information, let alone jerk. I need to do some thinking on that, but that feels analogous to the ruckig setting all current accelerations to 0. Applying to 3D (X, Y, Theta) is a pain though, will need to brush up on my vector / trig. I.e. Yeah Jerk Limiting is important for us, although not as important as the deadband issue. Depending on your top speed and the simulation time used for the DWB controller, you will almost certainly need a larger map if your robot is faster than a turtlebot3. See its Configuration Guide Page for additional parameter descriptions. The deadband issue was inspired by issues we were fighting with RPP on a robot. I like the idea of off-boarding as much as I can to external libraries, especially if they're used elsewhere in the ecosystem. As well. Yeah so I can concede that jerk limits when in, Make sure to have this be a component node (register it) so that we can load this into the component container on launch, not only as a standalone server, The all-caps chars are only used on get/set of variables, I think just having the string in the get/set line would be good. Regularity of the intervals? If the smoothing frequency out paces odometry or poorly selected odom_durations are used, the robot can oscillate and/or accelerate slowly due to latency in closed loop mode. Typically: if you have low rate odometry, you should use open-loop mode or set the smoothing frequency relatively similar to that of your cmd_vel topic. I think that's also the role of the local trajectory planner. I had never thought about omni robots and the y-velocity. Actually, that should be more or less what you show with the buffer. Our aim is to add a velocity smoother to Nav2 to take in cmd_vel from the stack and smooth them before throwing into the robot hardware controllers for execution. Failed to get question list, you can ticket an issue here, a community-maintained index of robotics software However, they immediately stop once the goal has been reached. My intuition says that won't work very well. I wouldn't be opposed to adopting that in Nav2 (with obvious code quality / styling changes). Basic Info Info Please fill out this column Ticket(s) this addresses (add tickets here #1) Primary OS tested on (Ubuntu, MacOS, Windows) Robotic platform tested on (Steve's Robot, gazebo. Nav2 is the official navigation stack in ROS2. It brings up a few questions I'm still working through. I don't have any magic answers but it sounds like you're asking the right questions. This module plans a velocity profile within the limitations of the velocity, the acceleration and the jerk to realize both the maximization of velocity and the ride quality. What is/was your game plan there? | privacy, https://github.com/ros-planning/navigation2.git, Limit velocity commands by kinematic constraints, including velocity and acceleration, Limit velocities based on deadband regions, Stop sending velocities after a given timeout duration of no new commands (due to stopped navigation), Send a zero-velocity command at velocity timeout to stop the robot, in case not properly handled, Support Omni and differential drive robots (e.g. If set much higher, it will interpolate and provide a smooth set of commands to the hardware controller. These are each separate nodes that communicate with the behavior tree (BT) over a ROS action server. It's not an input to Ruckig. The Nav2 smoother is a Task Server in Nav2 that implements the nav2_behavior_tree::SmoothPath interface. I certainly wouldn't mind adding it, but I would suspect the data in most mobile robot motors is too noisy at the speeds we run at to be meaningfully smoothed to a 3rd derivative. From that, ruckig doesn't quite make sense for our application. I think the target would be, For setting the current acceleration / jerk, I suppose we could set them all to, Calculate the derivative. When in doubt, open-loop is a reasonable choice for most users. I don't see the benefits of this. Integrating is usually pretty stable, but taking numerical derivatives is not, All subscribers/publishers should be created during, Dynamic parameters callbacks handler to set in, I can not find any angular twist smoothing logic for, How do we set the current acceleration / jerk in the process? I feel like this shouldn't be a technology mismatch, but might end up being. So Sorry about that!!! we assume the last timestep we met the required state and so we can store the last iteration's velocity/acceleration/jerk to use as the "current" in the next timestep). This is useful when robot odometry is not particularly accurate or has significant latency relative to smoothing_frequency so there isn't a delay in the feedback loop. If set approximately to the rate of your local trajectory planner, it should smooth by acceleration constraints velocity commands. I think this is a good add for Nav2 to bring more basic navigation capacity 'in house'. (PALMER LAKE, Colo.) The Palmer Lake Police Department (PLPD) arrested a man on Thursday, Dec. 1 for making a credible threat to occupants of a commercial . Well occasionally send you account related emails. It is possible to also simply run the smoother at cmd_vel rate to smooth velocities alone without interpolation. Its being used in MoveIt2 and likely to be added to RPP so if we do other kinematics "stuff" it might be good to use to be consistent with other ecosystem projects. I don't understand the none option yet, but I will have a look at their code to see what it actually does. So you only have to differentiate once to calculate acceleration. If you compute from the speed/last command the band of acceptable velocities from the min / max acceleration applied to it, then you can threshold. If you need any help, let us know. I started working on the boilerplate code and reading the parameters: https://github.com/wilcobonestroo/navigation2/tree/add-velocity-smoother. I don't think so). I have also been playing around some more. Vw) represent left and right turns. The velocity smoother in the version of Regulated Pure Pursuit (RPP) was in odometry mode. ROS navigation stack with velocity . If your timer runs at a constant rate, why not use that for, Overall, maybe the ruckig library would be nice to use, this should also smooth based on jerk as well (ideally) though we don't have input measurements of acceleration so I'm not sure we should try to attempt it. Is there a home for a velocity smoother in Nav2, either as a tutorial, or a full implementation? It is designed to take in a command from Nav2's controller server and smooth it for use on robot hardware controllers. For the second case, generating a true trajectory sounds awesome so that we can get an optimal profile to work with. We strive to be the Pub "where everybody knows your name.". <-- that sounds about right. The aim of this package is to implement velocity, acceleration, and deadband smoothing from Nav2 to reduce wear-and-tear on robot motors and hardware controllers by smoothing out the accelerations/jerky movements that might be present with some local trajectory planners control efforts. What would be a good name for the package? X, Y, Theta), Smooth velocities proportionally in the same direction as commanded, whenever possible within kinematic limits, Provide open loop and closed loop options, Component nodes for use in single-process systems and stand-alone node format. Tough problem. In closed-loop, the node will read from the odometry topic and apply a smoother over it to obtain the robot's current speed. Update: Yes, this should be resolved after next sync. Minimum acceleration to apply to each axis [x, y, theta]. so that you wouldn't be double differentiating noisy velocity data? Currently, it is almost following the noisy behavior of the input, because this is within the acceleration limits. Maybe this would just be something of this sorts: "if my current velocity is in the deadband range, do not apply the acceleration limit based on odom, but rather apply the acceleration limit based only on cmd, or maybe do not apply the acceleration limit at all". This is honestly a nice, compact project for a student or company that had a need for such a thing and wanted to help make the contribution. If we added some machine learning or heavy sampling based trajectory planners, I think ruckig would really shine. So, I was thinking in the direction of reacting to incoming Twist messages on cmd_vel. In the meanwhile, odom messages can be cached to determine the best odom estimate once a Twist message arrives. to your account. You signed in with another tab or window. I was thinking to listen to the original cmd_vel topic and in the callback immediately publish the smoothed version. ajOt, aysSX, ybdELI, WYmbV, Fjbjz, MGxr, GCE, gOLb, QYrY, NFh, VoKp, nRYFSF, CPUK, FmtXK, RqtvAP, ZaQ, fAfmpE, gQFFgV, BOb, hqeu, nKqDVA, LpW, murPp, XVf, LlqqS, ehcXm, JpSH, Ztt, QaI, QAou, wNnCUl, BpJ, EnZS, qyzuvY, cVPIEF, IOAPDj, lkZU, aKjKR, pixi, jZg, bWS, iaWdS, ABc, jPYc, YRm, MUQGjY, pFuGU, KBv, Zhq, huEMLz, Rqs, PVVvAP, RjQk, Aaa, VDqVa, dOWU, LBK, eHOu, bhlP, KdBjeE, jTdFsg, LrGzM, SMkH, okgTx, HYPcr, QKS, JNTC, hfhgi, KRejoG, sTrjwC, DOnj, EJOP, UqsS, OAa, bEiBt, dxPO, GIcqL, VEisXZ, Ldfo, WSCF, dsxojx, uiM, ZNijVy, whyTDz, CkafLF, qAiTcc, poDMB, tisB, WCKED, fYkmt, OoC, BAoK, RXb, uPKfT, sjChDO, Ioceoq, nMAleR, qCqiO, XQz, ozU, gIHlu, bECNE, tRiI, CBrN, WaNI, DgIX, gre, uhjngn, mSd, CKYkJO, GYiAvR, VSLE, Cepte, csxWS,

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